What does it mean when your alternator is not charging?
If the alternator is not charging the battery, you will have a red “ALT” or “charge” sign on your dashboard. This means that your battery is no longer being supplemented for power by the alternator. You will need to recheck the wiring because the light could also be faulty.
How can I tell if I have an alternator problem?
To differentiate an alternator problem from the battery, you will need to use a voltmeter to check for voltage. First, turn off the engine and check the battery voltage. A fully charged battery should have a reading of 12.65 volts. Next, turn on the engine and recheck the voltage. You should have a reading of 13.5 to 14.5 volts.
Can you drive a car with a faulty alternator?
Faulty diodes can easily be replaced, but you will need to dismantle the alternator. It is impossible to drive the car with a faulty alternator. While it is the work of the battery to power the electrical components in the car, it cannot do this alone.
Is the battery voltage on both sides of the alternator?
If you clear the codes and the warning comes back lets make sure the fusible links have power on both sides. Here is a guide and the alternator wiring diagrams to help you test and see how the system works. Check the two fusible links in picture they should have battery voltage both sides. The problem may be the PCM but lets run some tests first.
If the alternator is not charging the battery, you will have a red “ALT” or “charge” sign on your dashboard. This means that your battery is no longer being supplemented for power by the alternator. You will need to recheck the wiring because the light could also be faulty.
To differentiate an alternator problem from the battery, you will need to use a voltmeter to check for voltage. First, turn off the engine and check the battery voltage. A fully charged battery should have a reading of 12.65 volts. Next, turn on the engine and recheck the voltage. You should have a reading of 13.5 to 14.5 volts.
Faulty diodes can easily be replaced, but you will need to dismantle the alternator. It is impossible to drive the car with a faulty alternator. While it is the work of the battery to power the electrical components in the car, it cannot do this alone.
What kind of battery does Silverado Sierra 6.6L have?
I have a 2007 new body style Sivderado HD 2500 6.6L diesel with dual batteries a Bosch alternator and only 40k miles. The problem I’m having is it takes over 3 minutes from a cold start for my voltmeter to move from the 12 volts mark.
What happens when the alternator of a car is dead?
The alternator and the car’s battery work hand in hand. A good battery should give you service for the next five years before its lifespan ends. If your battery is dead, then it will not give power to the car’s alternator. The alternator normally lasts longer than the battery.
Can a car battery be drained by an alternator?
While you might initially think that any problems with electrical things like lights or radio not working are directly related to the battery, the alternator is actually where most of the power in your vehicle comes from. Consider that if you were to leave the lights of your car on overnight by the next day your battery might be drained completely.
Why would a good alternator not charge a battery?
The alternator is powered by several different wiring mechanisms. If a wire is not attached properly, becomes detached or is inadvertently cut, the alternator will not have any power. If the alternator is not getting any power, it cannot turn the pulley and belt mechanism that charges the battery, and the battery will not charge.
Why isn’t my alternator charging my battery?
6 Causes of an Alternator Not Charging Worn out carbon brushes or damaged alternator. The most common reason why your car is not charging is actually because of a worn-out or damaged alternator. Broken Serpentine belt. Faulty fuse. Wiring issues or connectors. Damaged car battery. Engine control module error.
What are signs of needing a new alternator?
- Warning Light. Many automobiles have a battery or alternator warning light on the dashboard.
- Load Test. Conducting a load test will indicate whether or not your alternator needs to be replaced.
- Voltmeter Test. You can test your charging system with a voltmeter.
- Other Signs.
What causes your alternator not to charge?
There are several different problems that can cause your alternator to stop working. Your car’s alternator charges the battery by generating power with a pulley and belt system. If the belt that controls that system snaps, stretches out or breaks, the alternator will stop working, and the battery will not charge.
How long does it take for an alternator to charge the car battery?
When your car engine runs, your car alternator may take more or less half-hour to recharge the battery fully. Again on a messy road, it takes relatively one hour.
What should the voltage of an alternator be?
Start your engine (up to 2000 RPM). Again taste the battery by running the engine in such away. If your battery is showing a reading in between 13 and 14 voltage that means your car alternator is fine. If you get a battery voltage less than this range, your alternator has some issues.
How long does it take to charge a battery from an alternator?
As long as the battery voltage rises when the engine is running, you know that your alternator is working. The ratio between the battery bank and the alternator will dictate how long it will take for the charging voltage to reach 14.4 volts.
Can a boat charge batteries from an alternator?
Unfortunately, on many boats, charging all the batteries from the alternator is a manual system and many boaters simply do not know or forget what position the battery switch should be set to, when and to charge which battery. An easy way to figure this out is through a process of cause and effect using the voltmeter gauge you have onboard.
What are the voltages of the batteries in an alternator?
With the single engine running at 1400 rpm, what are the voltages of the other batteries, did those voltages go up from the baseline voltages you measured prior to running the engine? If any battery voltage is now higher, you’ve confirmed there is either a battery combiner or battery isolator to share the charging voltage from the alternator.
Why is my car battery still not charging?
If you are sure that your alternator is working properly and yet your battery is still not charging, then it’s possible that you have a bad voltage regulator in your vehicle. The voltage regulator keeps the right amount of electrical power flowing through the various electrical systems in your vehicle.
Why is your new alternator not charging your battery?
The most common reason for an alternator not charging a battery is because of a bad alternator or battery . You can easily test the voltage by connecting a voltmeter to your battery while the engine is off.
Why is the battery warning light still on after replacing the alternator?
Put a meter across the battery after jumping it to get it started, had 12V. Bad alternator. At this point I don’t think the alternator problem is related to the non-working turn signals, hazards or horn. Replaced alternator, still 12V, and now the battery warning light is on??
Can a new alternator be installed on a low battery?
WARNING!!! The battery must have a charge in it of at least 12.8 volts. If the charge is lower than that, take the battery to an auto parts store and they should deep charge it for free. You should never install a new alternator in a system with a low charge battery. You could fry the bridge and then you are back to square one!
The alternator and the car’s battery work hand in hand. A good battery should give you service for the next five years before its lifespan ends. If your battery is dead, then it will not give power to the car’s alternator. The alternator normally lasts longer than the battery.
WARNING!!! The battery must have a charge in it of at least 12.8 volts. If the charge is lower than that, take the battery to an auto parts store and they should deep charge it for free. You should never install a new alternator in a system with a low charge battery. You could fry the bridge and then you are back to square one!
How long can a battery last without an alternator?
A good alternator and can last well over a decade, sometimes as long as 15 to 20 years. However, if an alternator does fail on you then you’ll know it fairly quickly as your electrical systems will fail soon afterwards. The charge in your battery does not last long without the alternator there to keep it running properly.
What should I do if my alternator keeps dying?
The alternator is essentially a generator and it keeps your battery charged while supplying additional electrical power for the other systems in the vehicle. If you have a new alternator and your battery keeps dying on you, then there’s definitely a problem that you’re going to need to look into.
What should I do if my alternator is not charging?
The alternator normally lasts longer than the battery. There are some easy steps you can go through to check the function of your alternator. Tap the alternator carefully with a hammer while the engine is runnin; if the charging goes back to normal, the coals inside it are worn out.
A good alternator and can last well over a decade, sometimes as long as 15 to 20 years. However, if an alternator does fail on you then you’ll know it fairly quickly as your electrical systems will fail soon afterwards. The charge in your battery does not last long without the alternator there to keep it running properly.
Why does a battery need an alternator to work?
The battery cannot supply all this power on its own, hence the need for the alternator. The alternator converts mechanical energy into electricity. The alternator is connected to a set of belts which when loose can cause it not to function as required.
Why does my alternator not charge on tickover?
On checking the battery voltage was low – 11.8V engine running. Battery was replaced about 1 month ago.After much investigation discovered that the alternator does not ‘kick in’ until I rev the engine to approx. 3000rpm – it then charges away happly for the rest of the journey (at around 14.5V) even on tickover. Has anyone seen this problem before?
Can a bad alternator be put out at 12V?
If the alternator is only put out 12V, it sounds like it may have a bad diode. If you’re not running anything but the engine, you should see at least 14.5V.
Can a broken belt cause an alternator to not charge?
The alternator will not be able to charge if your belt wears down over time. Fortunately, the broken belt is easy to replace, and can be a quick fix to get your alternator backup and charging again. A broken pulley goes hand-in-hand with the broken belt. The pulleys and belts are part of the system which converts energy into the alternator.
Where does the alternator go in a Mitsu?
The alternator harness goes to the fusebox and that diode or the “generator relay” that Mitsu calls it hangs around the fusebox. Then, you have those 4-white wires that go into the fusebox between the 100A fuse and the fusible link. I am doing a wire tuck right now.
What should the charge voltage be on an alternator?
Turn on the high beams for 10 seconds and then turn them off. Measure battery voltage across the battery posts with your DMM. You should get between 12.4 and 12.6V. This means your battery is fully charged. If you get a reading below 12.4V, charge the battery before continuing. 5b. Measure the Charging System’s No-Load Voltage
Why does my alternator not charge my battery?
If you’re getting less voltage than that, then your battery is not able to hold a proper charge. Bad Battery Connection It’s possible that if your battery isn’t charging and your alternator is working fine that you have an issue with the terminals, or the wiring connected to your battery.
Where does the charging warning light go on an alternator?
Black and yellow goes from the alternator plug to that generator relay. Blue wire goes from generator relay to that interior harness (C25) which goes to the instrument panel wiring (My 3rd pic the plug on the left) which looks to be for the instrument cluster for the “charging warning light”. Click to expand… Gotcha.
The alternator will not be able to charge if your belt wears down over time. Fortunately, the broken belt is easy to replace, and can be a quick fix to get your alternator backup and charging again. A broken pulley goes hand-in-hand with the broken belt. The pulleys and belts are part of the system which converts energy into the alternator.
Why is there a noise coming from my alternator?
Noise from the alternator could be caused by a faulty rotor shaft, rectifiers, bearings, slip rings, stator winding or brushes. You will need to carefully inspect each of these components and replace them. One sure way of confirming that the noise is coming specifically from the alternator is to use a vacuum hose.
Why does my Hyundai Accent battery keep dying?
Why does my car keep dying? – 2008 Hyundai Accent New alternator and battery…. New alternator and battery. Why does my car keep dying? So recently I experienced some issues with my car where it would shut off while at idle. A mechanic suggested to me the symptoms seemed to point to my alternator or battery.
How much does it cost to replace an alternator and battery?
A $5 fix! Probably will need battery charged or replaced because car has been running directly from it. Sorry U had to unnecessarily replace an alternator. Most people will have U do that as guesswork. Good luck
What will happen if you put a wrong alternator?
When the wrong alternator has been installed in a stock vehicle or if the pulley has undersized dimensions (causing extra alternator rotation), the charging supply will be higher than the demand and cause an overcharged state. High performance or racing alternators should not be installed on stock passenger vehicles.
What happens when you disconnect the battery on a Jaguar?
When the battery is disconnected, these adaptations are lost. On reconnection, therefore, some slightly abnormal drive symptoms may occur and the vehicle may need to be driven10 miles (16 kilometres) or more while the control system re-adapts. this is a simple link for resets after battery disconnect.
How to reset the ecu-1 Jaguar car forum?
Restart the clock (where fitted) and set it to the correct time. Simultaneously press “>>” “PTY” “A.MEM” should only take 2 or 3 seconds and the radio turns on. 1. NOTE: After the battery has been disconnected it is necessary to
Another sign that your alternator is not charging is that the dash lights and headlights will get lower when your car is idling, but become brighter when you rev your engine. This means that you could have a weak alternator, or a poor connection at the battery terminals.
When the battery is disconnected, these adaptations are lost. On reconnection, therefore, some slightly abnormal drive symptoms may occur and the vehicle may need to be driven10 miles (16 kilometres) or more while the control system re-adapts. this is a simple link for resets after battery disconnect.
While you might initially think that any problems with electrical things like lights or radio not working are directly related to the battery, the alternator is actually where most of the power in your vehicle comes from. Consider that if you were to leave the lights of your car on overnight by the next day your battery might be drained completely.
If you are sure that your alternator is working properly and yet your battery is still not charging, then it’s possible that you have a bad voltage regulator in your vehicle. The voltage regulator keeps the right amount of electrical power flowing through the various electrical systems in your vehicle.
Is the battery good with a new alternator?
Battery voltage was too low to test, so I took battery out and left it out overnight, next morning picked it up, they said battery was good and held charge. Put battery back in and took it for testing, their test said the voltage regulator was bad, so bought a new alternator, installed it, same thing, not charging.
Can a weak battery destroy an alternator?
A weak battery can adversely affect your alternator in the long run. Imagine a scenario where your car broke down and won’t start. You have a busy day ahead of you but you’re a car guy and your vehicle is a priority to you.
How many volts should my alternator be charging at?
A car alternator needs to be putting out at least 13-14 volts (ideally between 13.8 and 14.2 volts) to effectively charge a 12 volt car battery. If the alternator is putting out too much voltage (15+ volts), it is likely your battery acid will boil over out of the battery.
Can a battery be worn as an alternator?
IF the VR checks out, ensure the electrical harness to/from the alternator is secure and not damaged. If the vehicle has significant amount of miles (ie. 100,000 +), the alternator brushes may be worn. Please note, the battery is only used (under normal conditions) to start the vehicle.
How do I know if my battery or alternator is bad?
Signs of a bad alternator. If the above steps reveal that the battery is working, it’s time to take a closer look at the alternator. There are certain signs of a bad alternator to look for: While running the car, note the brightness of the interior lights. If the dashboard gradually dims, the alternator is likely at fault.
Why does my Jaguar XJ6 X300 have no alternator?
Most commonly this is caused by a wiring problem Test for B+ on the White/Blue, Grey/White and the Black wire at the alternator.Start the vehicle and check the voltage on the Grey/White wire, B+ is normal, a ground indicates a failed alternator.
How does the alternator work on a Jaguar?
The instrument cluster supplies the Grey/White wire with power through the charge indicator light and the alternator grounds it until vehicle is started, then the alternator produces a voltage on the Grey/White taking away the ground and putting out the charge light.
Is the alternator the only thing that powers the car?
Many people assume that the car’s battery is the only thing that powers all electrical components in the car. But, this is not true. The alternator plays a vital role in supplying power to the car’s AC, recharging the battery and ignition.
Is there a problem with the JAG battery?
The same Jag has always had a battery drain problem. If the car is driven everyday, there is usually no problem the next Jaguar XJ8 L: The same Jag has always had a battery drain problem. Experience: 30 years of experience working with Jaguars. Independent European shop owner and technician. Hello, I’m Jason.
How to test battery drain on Jaguar XJ8 L?
Here’s a draw test procedure that I recommend for the battery drain Open your hood, and then manually re-latch the latch using a screwdriver or similar (we’re re-latching so that the alarm computer will think all latches are closed). Open driver’s door, and also re-latch.
Is there a problem with the Jaguar XJ8 L?
If the car is driven everyday, there is usually no problem the next Jaguar XJ8 L: The same Jag has always had a battery drain problem. Experience: 30 years of experience working with Jaguars. Independent European shop owner and technician. Hello, I’m Jason.
How does the jagrepair XJ Series sedan work?
In addition to the two networks , the XJ Series uses two serial data buses (ISO) for diagnostics, for the security system and for the programming of certain control modules. The XJ Series uses both power and logic grounds; however, it does not use a common logic ground stud connection as in previous Sedan vehicles.
When do I need jumper cables for my alternator?
However, when jumper cables are needed, be sure to get the battery fully-charged with a battery charger as soon as possible. As the alternator instructions suggest, our REDTOP® batteries are fully-charged at about 12.6-12.8 volts and our YELLOWTOP® and BLUETOP® batteries are fully-charged at about 13.0-13.2 volts.
How much does it cost to replace an alternator on a Chrysler?
The good news is it is covered under the Emissions Warranty (8yr/80K miles), and won’t cost me a dime. And by installing the alternator myself, I saved $500 (dealer estimate was $700). Woohoo! :biggrin: I can’t thank you enough for your help.
Many people assume that the car’s battery is the only thing that powers all electrical components in the car. But, this is not true. The alternator plays a vital role in supplying power to the car’s AC, recharging the battery and ignition.
Why does my alternator get higher than base voltage?
You should get 0.5 to 2 volts higher than base voltage. If you are getting more than 2 volts above base voltage, most likely your alternator is over-charging the battery or the battery is faulty. Other potential problems are a faulty voltage regulator or a problem in the charging system wiring.
Another sign that your alternator is not charging is that the dash lights and headlights will get lower when your car is idling, but become brighter when you rev your engine. This means that you could have a weak alternator, or a poor connection at the battery terminals.
The terminal voltage going down to 13.1v suggests the battery is not charging, and may be discharging, unless the battery is very low. The alternator or the battery is probably in poor condition. The alternator will charge the battery at a constant voltage (usually 13.8, or 14.2), and electively never a constant current.
Can a car run off of an alternator?
No, absolutely not! Your car runs off of the alternator. The battery is only there to start the engine. It incidentally also acts to smooth the output of the alternator, but the battery’s primary purpose is to start the vehicle.
How can I tell if my alternator is working or not?
If you’re not 100% sure, you can use a multimeter, or a voltmeter, to check the current coming from your battery. Attach the positive lead to the positive battery terminal, that’s the red one, and then the negative leave it to the black terminal. With the engine off you should be getting a reading of 12.5 volts on your multimeter.
How does an alternator and battery work together?
Anything less than that and your car isn’t even able to start. Both of these car parts control your electrical system. However, your alternator charges your battery while your battery supplies power to your car. The failures of a battery are sudden, while failures of a failing alternator are slow.
What happens if you have a bad alternator on a Jeep Compass?
As described above, a bad alternator will drain your Compass’s battery fast. When the battery gets so dead it will no longer be able to power your Compass’s ignition system. As the ignition system is no longer able to produce a full powered spark, the engine will begin to sputter and stall.
What happens if you have a new alternator and the battery is not charging?
The alternator in your car is an integral part of your vehicle’s electrical system. If you have a new alternator and the battery is still not charging, then you definitely have some kind of a problem with your battery that you’ll need to address immediately.
Can a bad alternator cause a bad PCM?
If these are all good, then you need to check the wiring between the PCM and the alternator, or the PCM itself may have a problem. Another possibility is a bad Battery Temperature Sensor.
What are the symptoms of a bad alternator?
Outside of the battery warning light, a dead battery is the most common symptom of a bad alternator. As the alternator can no longer supply your Compass with an adequate power supply, it will begin to feed off of the reserve in the battery.
If these are all good, then you need to check the wiring between the PCM and the alternator, or the PCM itself may have a problem. Another possibility is a bad Battery Temperature Sensor.
Why is the alternator on my Jeep not charging?
Looks like the field coil of the alternator isn’t getting power. There are 3 wires attached to the alternator. One is a big fat wire that goes to the battery, this is the alternator output. The other two wires feed power to the field coil.
Why is my alternator not charging on my scanguageii?
Talked to a couple of people and started a thread on another site and the consensus was that my alternator died (it was a 3-4 year old large case 200a unit from alternatorparts). Ordered a 220a unit from DB Electric and installed it last night……aaaaaaand I’m still at 12v or less on the ScanGuageII. Began troubleshooting and here’s where I’m at:
Is the alternator at the heart of the charging system?
Dan Ferrell writes about do-it-yourself car maintenance and repair. He has certifications in automation and control technology. The alternator is at the heart of the charging system of your vehicle. Alternator problems and charging system problems can affect your vehicle in different ways.
Can a bad car battery cause an alternator to not charge?
In theory a car can run only with the alternator charge, but this can cause heavy voltage spikes and other strange symptoms so this means that a bad car battery can cause an alternator to not charge also. Cars are increasingly coming with modern electronics.
Start your engine (up to 2000 RPM). Again taste the battery by running the engine in such away. If your battery is showing a reading in between 13 and 14 voltage that means your car alternator is fine. If you get a battery voltage less than this range, your alternator has some issues.
What should I do if my alternator is not working?
The solution is to check your car’s manual for the particular fuse that controls the alternator and replace it. In some cars, you might also find another small fuse to the alternator’s control—usually a 15A to 20A fuse. An alternator does usually has 3 or 4 wires to it to function properly.
Is there a problem with the alternator in Liberty?
Discussion in ‘ Liberty ‘ started by jonahb1987, Jul 10, 2019 . I recently had a breakdown. At first we thought it was the alternator, so I bought a new one. Had it installed at a mechanic and the same problem would happen. After being jumped, it would start but putter out in like 4 minutes.
What happens when the diodes in an alternator go bad?
Alternators use diodes to rectify alternating current produced by the alternator into direct current. When one or more diodes go bad, the alternator can cause all kinds of problems. AC voltage leak can cause your lights to dim and drain power from your battery, for example.
The alternator is essentially a generator and it keeps your battery charged while supplying additional electrical power for the other systems in the vehicle. If you have a new alternator and your battery keeps dying on you, then there’s definitely a problem that you’re going to need to look into.
Alternators use diodes to rectify alternating current produced by the alternator into direct current. When one or more diodes go bad, the alternator can cause all kinds of problems. AC voltage leak can cause your lights to dim and drain power from your battery, for example.
The battery cannot supply all this power on its own, hence the need for the alternator. The alternator converts mechanical energy into electricity. The alternator is connected to a set of belts which when loose can cause it not to function as required.
Why is my alternator not working on my Kia Sedona?
Battery light and brake light indicators would come on for a few seconds then go off. After about a week of that the lights stayed on and sedona would not start because of no battery charge. Alternator was covered in oil from the valve covers leaking (another common issue). Replaced.
What causes a battery light to come on after an alternator is installed?
The most common is, again, a loose connection either with the control plug (aka “relay” plug-in), charging line connection, or the ground. The other is a blown fuse or defective connector or relay, which could have been broken or shorted when the alternator was installed or on the first start-up after its installation.
How can I tell if my Toyota alternator is charging?
I’ll have to double check, but it should only be around 300 mA once the fuel pump is off. To do this, disconnect one of the battery terminal wires. Turn the ignition to the ON position and turn your radio and all lights off including your dome light.
What are the symptoms of a faulty alternator?
A faulty or dying alternator is usually the problem, if the battery checks out ok. Symptoms of a faulty alternator include car not starting, headlights dimming or a charging system warning light on the dashboard.
What is the function of an alternator in a car?
The main function of the alternator is to power the car’s battery. When your AC, headlights, and stereo are on, a lot of power is needed. The battery cannot supply all this power on its own, hence the need for the alternator. The alternator converts mechanical energy into electricity.
The main function of the alternator is to power the car’s battery. When your AC, headlights, and stereo are on, a lot of power is needed. The battery cannot supply all this power on its own, hence the need for the alternator. The alternator converts mechanical energy into electricity.
Do you have to connect a battery wire to an alternator?
You only need to connect the battery wire (one-wire). The alternator turns on the voltage regulator when the engine starts turning the alternator. Most standard and all self-exciting regulator alternators will work using the two wire setup. #1 terminal to activate the alternator.
How to diagnose computer-controlled charging systems?
Suppose you’re working on a GM charging system with the common terminals I described earlier (P-L-I-S or P-L-F-S). The alternator isn’t charging and you’ve already checked the ground and output circuits. Shut off the ignition switch and unplug the harness connector from the alternator.
What should one wire alternator output be at idle?
Crank the engine while probing the battery posts. It should not go under ~10.5vdc at least. When the engine is at idle, 14.0 -13.8 vdc. Stop engine. Disconnect the alternator lead And start the engine. From the alternator output to the ground should be at least 13.5-14.0vdc.
What to do if your alternator has bad ground?
Place the red lead on the positive battery terminal (if possible dig it into the battery post, not the terminal). Place the black lead on the bad post of the alternator. Same thing as above, if the voltage is above 0.5v then examine the positive cabling for problems.
What causes an alternator to output low volts?
If the voltage at the battery and alternator don’t match. For example the battery reads 12v and alternator reads 14v. This means that there is an issue with wiring. While applying the same conditions as above.
When to troubleshoot an unusual voltage system drop?
Troubleshooting for Unusual Voltage System Drops Usually, the first sign that your charging system is in trouble is a “battery,” “ALT,” or “CHARGE” warning light illuminating on your instrument panel while driving. It means that for some reason, the alternator has stopped charging the battery and your car is running on battery power.
Can a bad ground wire cause a car battery to not charge?
The ground is a major part of the battery’s charging system, so assuming that you’re getting proper voltage output from the alternator wire, and the battery isn’t hashed, then you may be looking at a bad ground wire. If the ground wire is loose, then the alternator won’t deliver its full power to the battery, particularly at idle.
Place the red lead on the positive battery terminal (if possible dig it into the battery post, not the terminal). Place the black lead on the bad post of the alternator. Same thing as above, if the voltage is above 0.5v then examine the positive cabling for problems.
If the voltage at the battery and alternator don’t match. For example the battery reads 12v and alternator reads 14v. This means that there is an issue with wiring. While applying the same conditions as above.
If the voltage is still only 12.4-12.6 once the engine is running, then the charging system is not functioning. In most cases and in most vehicles, you will have a battery light illuminated that indicates that the alternator is not charging.
Why does AutoZone test the alternator and charging system?
Keep in mind, when you test your charging system while the car is running, or AutoZone does the same, the system voltage is being tested at the battery, and if it’s not getting a charge, the test cannot determine why. Either the alternator itself is at fault, or the wiring between it and the battery are.
What should voltage be between battery and alternator?
Very low differences in voltage between the battery and alternator should also be suspect – say – 12.8 volts at the battery. The first course of action is to check the wiring carefully that runs between the alternator’s main power wire and the battery.
What does the charge indicator light mean on a car?
Indicator Light On Usually, the first sign that your charging system is in trouble is a “battery,” “ALT,” or “CHARGE” warning light illuminating on your instrument panel while driving. It means that the alternator voltage output is below 12 volts, or over its limit or has stopped charging the battery and your car is running on battery power.
If the voltage is still only 12.4-12.6 once the engine is running, then the charging system is not functioning. In most cases and in most vehicles, you will have a battery light illuminated that indicates that the alternator is not charging.
Keep in mind, when you test your charging system while the car is running, or AutoZone does the same, the system voltage is being tested at the battery, and if it’s not getting a charge, the test cannot determine why. Either the alternator itself is at fault, or the wiring between it and the battery are.
Very low differences in voltage between the battery and alternator should also be suspect – say – 12.8 volts at the battery. The first course of action is to check the wiring carefully that runs between the alternator’s main power wire and the battery.
How to know if your alternator is working properly?
1 Check the drive belt or serpentine belt. Look for signs of wear or damage like cuts, shiny spots or missing chunks under the belt. 2 Also, check the belt tensioner for proper operation and damage. It should rotate freely. 3 Make sure the alternator is properly mounted. 4 Check the alternator for noises.
Why is my Ford F-150 not charging?
Please try again later. On many Fords the alternator has a ‘smart charge system’ that regulates the output of the alternator to ensure the battery is being charged efficiently, reducing emissions and improving performance. So let’s come along with Eric O. at the SMA shop as he diagnoses this F-150 that came in with a no charge condition.
Can a bad battery cause an alternator to over charge?
Make sure that all the connections to the alternator, remote voltage regulator (if applicable) and battery are clean, tight and in good condition. Check your battery or have it tested at your local auto parts store. A bad battery cell can cause the alternator to over-charge the good battery cells.
How can you tell if your car charger is in trouble?
Usually, the first sign that your charging system is in trouble is a “battery,” “ALT,” or “CHARGE” warning light illuminating on your instrument panel while driving. It means that for some reason, the alternator has stopped charging the battery and your car is running on battery power.
What causes a car alternator to stop working?
The alternator will stop working the moment your belt wears out and breaks or the pulley becomes damaged. These items are easy to replace. 3. Faulty fuse Fuses blow up due to a power surge or they wear out. When this happens, current will stop flowing to the alternator.
What should the voltage be on an alternator?
Run the engine at 2k RPM. Turn on all the loads (blower on high, headlights on, rear defrost on, and so forth). Measure the voltage across the battery and the big bat alternator terminal to alternator case. There are two things that you are looking for. The charging voltage should be between 13.9v to 14.4v.
Do you need a DC charger for a Smart alternator?
The vehicle has a battery monitor attached and regulates the charging. However as we all agree if you want 100% charging of the leisure batteries you need a dc-dc charger as a simple split charge relay is nit suitable for smart alternators. MOLL battery issue. Stop/start…regen…smart Alternator…
The vehicle has a battery monitor attached and regulates the charging. However as we all agree if you want 100% charging of the leisure batteries you need a dc-dc charger as a simple split charge relay is nit suitable for smart alternators. MOLL battery issue. Stop/start…regen…smart Alternator…
You should get 0.5 to 2 volts higher than base voltage. If you are getting more than 2 volts above base voltage, most likely your alternator is over-charging the battery or the battery is faulty. Other potential problems are a faulty voltage regulator or a problem in the charging system wiring.
What causes an alternator to go over base voltage?
If you are getting more than 2 volts above base voltage, most likely your alternator is over-charging the battery or the battery is faulty. Other potential problems are a faulty voltage regulator or a problem in the charging system wiring.
Can a bad alternator Fry a new battery?
The flip side is that a defective alternator can fry a battery, also. So replacing a battery and having the new one go bad soon afterward might mean the alternator was bad to begin with. A depressingly large number of people don’t test the charging system after replacing a battery.
Can a bad solenoid be a sign of a bad starter?
Intermittent operation can be a sign of a failing starter solenoid. Other issues that present like a bad solenoid. Problems that might cause your car to act like it has a bad starter solenoid can include: Bad battery – If the battery voltage is low it will be unable to provide enough power to start your engine.
Can a bad alternator cause a bad starter?
If the alternator is bad, the battery may not be capable of starting the engine. Starter – Some solenoids are mounted to the starter, but some are located directly inside the starter housing. When this is the case, it may be necessary to replace the entire starter when the solenoid goes bad. Sometimes the starter itself is the problem.
Why is the battery on my ALINEr not charging?
There will be a slight draw on the batteries from the radio presets and engine CPU for the engine battery, and a draw from the LP leak detector so it’s good to isolate those. My battery on my aliner is not charging after I drive with it all connected to my destination. The battery itself was tested and is chargeable.
What should the voltage be on a bat alternator?
Measure the voltage across the battery and the big bat alternator terminal to alternator case. There are two things that you are looking for. The charging voltage should be between 13.9v to 14.4v. Also the voltage at the battery and the voltage at the alternator should be within 0.5v of each other.
If the alternator is bad, the battery may not be capable of starting the engine. Starter – Some solenoids are mounted to the starter, but some are located directly inside the starter housing. When this is the case, it may be necessary to replace the entire starter when the solenoid goes bad. Sometimes the starter itself is the problem.
What makes an alternator not charge the battery?
That’s a bad regulator hands down. Sounds like its not regulating anything anymore and its sending full field voltage to it causing it to max out on the charge. Anything over 14.8 is abnormal usually, anything over 16 can start to eff up electronics, you’ll be lucky if your ECU/TCU survive too many of those spikes
If your not getting a reading from there you can check your output from your alternator. Make sure you ground your multimeter, and put the power side to the stud that is coming out from the alternator (should be nut holding your wires that go to your battery).
What did I do when my alternator died?
I was driving on the freeway and my car started to make a weird noise. Pulled over to the next lane for the next exit. It automatically died and locked up. I kicked it in neutral and forced it onto the shoulder. Roughly a week or two before that I replaced the alternator and it was running great.
What happens when an alternator has an electrical problem?
After the engine starts (thanks to the high voltage provided by the battery), the alternator provides the electricity required to power the car’s many electrical functions, including the lights and radio, the spark, charging the battery, and others. What Happens When Your Car Has an Electrical Problem?
When to use battery light to test alternator?
The other critical tool to effectively diagnose an alternator is a scan tool. On older vehicles, the battery light would turn on the alternator light when the alternator output or battery voltage dropped below a preset value. The battery light on modern vehicles, however, is controlled by data and trouble codes.
In the event your battery’s good, start the vehicle and get the engine up to 2,000 RPM. This will put a lot more demand on the alternator. A decreasing voltage reading on your voltmeter indicates you have an alternator problem.
Can a bad ECM drain the battery all at once?
This is where the voltage regulator comes in, it allows the alternator to maintain the correct amount of voltage so that the alternator does not exceed the amount of voltage supplied to the battery. Too much voltage supplied to the battery and components can begin to fry, too little and the battery will not charge at all.
What should my alternator voltage be when I start the car?
The voltage reading should be between 12 and 13 volts. You can automatically assume there’s a battery problem when the reading is lower. In the event your battery’s good, start the vehicle and get the engine up to 2,000 RPM. This will put a lot more demand on the alternator.
This is where the voltage regulator comes in, it allows the alternator to maintain the correct amount of voltage so that the alternator does not exceed the amount of voltage supplied to the battery. Too much voltage supplied to the battery and components can begin to fry, too little and the battery will not charge at all.
You can easily test the voltage by connecting a voltmeter to your battery while the engine is off. The voltage reading should be between 12 and 13 volts. You can automatically assume there’s a battery problem when the reading is lower.
The alternator harness goes to the fusebox and that diode or the “generator relay” that Mitsu calls it hangs around the fusebox. Then, you have those 4-white wires that go into the fusebox between the 100A fuse and the fusible link. I am doing a wire tuck right now.
What to do if your alternator and battery are disconnected?
A crimper, some wire and a couple of terminals later, and things are running solidly again. TL;DR Check your resistance from the alternator to the positive terminal connection of the battery (with the battery disconnected), to see if your charge is getting to the battery.
Why does my alternator not charge the battery?
If I leave the generator relay unplugged, the battery light does not work at all. If I bridge the wires it will only come on with the car off and key forward. I did notice however that the battery light is slightly more dim than the rest of them. A picture of the back of the plug and what wires go where would be much appreciated.
Where does the generator relay plug go on an alternator?
The alternator harness goes to the fusebox and that diode or the “generator relay” that Mitsu calls it hangs around the fusebox. Then, you have those 4-white wires that go into the fusebox between the 100A fuse and the fusible link. Click to expand… I just need the one for the “generator relay” plug.
Is there a problem with the Nissan 240SX battery?
Charging Problem – Battery Not Charging but Alternator OK! – Nissan Forum | Nissan Forums Charging Problem – Battery Not Charging but Alternator OK! ONLY for ADVANCED technical discussion about the 240sx! Charging Problem – Battery Not Charging but Alternator OK!
The voltage reading should be between 12 and 13 volts. You can automatically assume there’s a battery problem when the reading is lower. In the event your battery’s good, start the vehicle and get the engine up to 2,000 RPM. This will put a lot more demand on the alternator.
Charging Problem – Battery Not Charging but Alternator OK! – Nissan Forum | Nissan Forums Charging Problem – Battery Not Charging but Alternator OK! ONLY for ADVANCED technical discussion about the 240sx! Charging Problem – Battery Not Charging but Alternator OK!
Do you need to check the battery first before checking the alternator?
Check the battery first. The battery is needed to start the vehicle, which, in turn spins the alternator at sufficient speed to keep the battery charged.
Why does my aftermarket alternator keep blowing up?
Aftermarket alternators on some vehicles are known to have this type of problem. The vehicle computer box might be controlling your charge rate to the battery and blowing alternators up due to excessive resistance. Rectifier diodes in aftermarket alternators are known to pop like this.
Why does my car battery charge but not charge?
Alternator problem occur because the alternator charges the battery when the car is running. If you jump the battery and it only remains charged for a little while, that’s a positive sign of a faulty alternator. However, it’s very important to have your car thoroughly inspected before you replace anything.
Do you start from the battery or the NEG?
If so, start from the battery and clean up every connection pos and neg. Neg perhaps more importantly because the pos is connected via wire from battery to starter more or less directly.
Can a Saab 92 start with a bad alternator?
Dual ignition coils (the blue cylinders at the top of the picture) on a Saab 92. Before you go out and order a new battery or alternator, test some of these different systems. If your alternator, coil, battery, or starter is bad, the car probably won’t start, and it definitely won’t be drivable.
Why does my alternator light get brighter when I Rev the engine?
This voltage drop causes the light to light, and also results in the battery charging poorly if at all. Usually when this is the case, the light will be very dim at hiatal and will get brighter as you rev the engine.
This voltage drop causes the light to light, and also results in the battery charging poorly if at all. Usually when this is the case, the light will be very dim at hiatal and will get brighter as you rev the engine.
What causes a radiator alternator to stop working?
A closer observation of the radiator will reveal a system of pulleys or belts that work to convert mechanical energy into electrical energy. The alternator will stop working the moment your belt wears out and breaks or the pulley becomes damaged. These items are easy to replace. 3. Faulty fuse Fuses blow up due to a power surge or they wear out.
Where can I find Nissan 280ZX battery parts?
So if you are looking for any Datsun / Nissan Electrical parts, or just need Datsun & Nissan 280ZX Charging Parts, Z Car Source has all the Z Car parts for your Datsun / Nissan 240Z, 260Z, 280Z, 280ZX and 300ZX. New Nissan 280ZX Battery Frame for the 1979-83 Datsun/Nissan 280ZX.
Where can I get parts for my Datsun 240Z?
With Datsun / Nissan offerings from Doors to Engines and everything in between, Z Car Source is the place to go for your Datsun 240Z, 260Z, 280Z, Datsun / Nissan 280ZX and Nissan 300ZX needs. New OEM, Aftermarket, Refinished, Rebuilt or Used – we have the most options for Z Car Parts on the web.
Why does the battery light come on after the alternator is replaced?
This would make the Battery Light come on. It is also possible that there is a problem with the fusible link or the alternator fuse for the charging system.
Why is my alternator not charging my car?
I now know I have a good alternator installed, a good battery, but the 13.5V – 14.5V that is being generated by the alternator isn’t making into the circuit.
What does an alternator do in a Nissan Maxima?
The alternator’s job in your Maxima is to provide electricity as it is running. The battery stores enough voltage to be able to start the engine without the assistance of an alternator. It is turned by a serpentine belt.
How to troubleshoot an alternator and charging system problem?
If necessary, adjust the belt with the help of your car owner’s manual or repair manual. Inspect the belt for signs of cracks, cuts, shiny spots, deterioration or other signs of wear or damage. Change the belt and belt tensioner at the manufacturer’s recommended interval. 2. Check for Wiring Problems
What happens when the battery dies on a Nissan Maxima?
When the battery gets so dead it will no longer be able to power your Maxima’s ignition system. As the ignition system is no longer able to produce a full powered spark, the engine will begin to sputter and stall.
When to replace the alternator in an Audi A4?
With the engine just fired up, you should get over 14.2 volts. If you got 14.2 or more volts, the alternator is charging fine. If it’s still showing in the 12’s, it’s time to replace the alternator. If it’s producing a voltage level in the 13’s, go ahead and take it into a parts store and have it tested.
Why is my alternator not charging my battery?
The most common reason for an alternator not charging a battery is because of a bad alternator or battery. You can easily test the voltage by connecting a voltmeter to your battery while the engine is off.
What happens if you start your car without an alternator?
If you were to try and start your vehicle without an alternator, the battery alone would not be able to produce enough power to get the engine running. Even if you had a new car battery and were lucky enough to turn the engine over, it would probably run for about 10 minutes before the power cuts out.
How often does a car alternator need to be charged?
Alternators and batteries do not last forever, and each have their own lifespans. A car battery will last from 2 to 5 years, depending on how often you drive and the climate where you live. Batteries generally last longer in colder environments and shorter in hotter environments. Alternators will last about 7 years or every 80,000 miles.
Can a B2B Charger charge a camper alternator?
If you have a 100 amp battery bank, charge via the alternator using a sub 50-Amp B2B Charger If you have a 200 amp battery bank, charge via the alternator using a sub 100-Amp B2B Charger. UNLESS your alternator is smaller than 140 amps, you could, in that case, use an Isolator.
What’s the best charge rate for an alternator?
Higher charging rates can lead to premature alternator wear and potentially alternator overheating. Vehicle Alternators generally put out 13.5V to 14.5V depending on their quality, design, and age. Large wire size, potentially up to 2/0 wire, should be used due to minimizing voltage drop (Less than 3%) while accommodating high charging rates.
If you have a 100 amp battery bank, charge via the alternator using a sub 50-Amp B2B Charger If you have a 200 amp battery bank, charge via the alternator using a sub 100-Amp B2B Charger. UNLESS your alternator is smaller than 140 amps, you could, in that case, use an Isolator.
Higher charging rates can lead to premature alternator wear and potentially alternator overheating. Vehicle Alternators generally put out 13.5V to 14.5V depending on their quality, design, and age. Large wire size, potentially up to 2/0 wire, should be used due to minimizing voltage drop (Less than 3%) while accommodating high charging rates.
When does the Van charging system isn’t charging?
No indication when van charging system isn’t charging ie a Mil light switched like in old dynamo days. What you described is normal operation for bluemotion. The alternator goes into idle once the starter battery is at 80% to save fuel and give headroom for the regenerative braking.
How does the alternator work in a car?
Almost all cars with an internal combustion engine contain an alternator as well. When the engine in your car is running, the alternator’s job is to maintain a proper charge in the battery and supply electric power to the vehicle’s electrical systems. The alternator is connected to the engine and is controlled by a drive belt.
What to do if your alternator is over charging the battery?
Ask an assistant to start the engine and hold engine speed at about 1500 RPM. Measure voltage across the battery with your DMM. You should get 0.5 to 2 volts higher than base voltage. If you are getting more than 2 volts above base voltage, most likely your alternator is over-charging the battery or the battery is faulty.
What to do if your alternator won’t charge your battery?
Make sure you ground your multimeter, and put the power side to the stud that is coming out from the alternator (should be nut holding your wires that go to your battery). If your getting 13.5-14.5V there then the connection between the alternator, and battery is bad.
A closer observation of the radiator will reveal a system of pulleys or belts that work to convert mechanical energy into electrical energy. The alternator will stop working the moment your belt wears out and breaks or the pulley becomes damaged. These items are easy to replace. 3. Faulty fuse Fuses blow up due to a power surge or they wear out.
What happens when the serpentine belt fails on an alternator?
The serpentine belt powers the alternator, and if it fails, the alternator will stop working the moment your belt wears out and breaks, or the pulley becomes damaged. This can also happen if the serpentine belt is not tightened correctly. Most cars have automatic tensioners, but these can fail, so it is better to double-check.
How many wires does an alternator need to charge?
An alternator does usually has 3 or 4 wires to it to function properly. You will find one big main cable together with two or three small ones. All these wires are important for the alternator’s function, and if one breaks off – you might lose the charging function.
How is the alternator pulley held in place?
The alternator pulley is actually made of two separate parts. It is held in place by a 24mm nut (yellow arrow) but you will need to use a M10 12 point to hold the alternator shaft from turning (red arrow) while loosening the nut with the 24mm wrench. Remove the nut and the spacer behind it, there may also be some flat shims behind this spacer.
How does the alternator work on a Porsche 993?
While the older Porsche’s use a single belt to run both the cooling fan and the alternator, as displacement increased and there became higher demands on the electronic systems, Porsche designed an independent pulley system for the 993 alternator and cooling fan.
How do you install a new alternator belt?
Install new fan belt. Just like with the fan belt, place the new alternator belt over the crank pulley first and then center the other end over the alternator shaft. Replace the shims. Slide the pulley half on the alternator shaft and then thread the 24mm nut on.
How do you install a fan on an alternator?
Place the fan belt onto the crank pulley first and then align the center of the top of the belt with the alternator shaft. Re-install the shims you removed in Step 5. Place the outer half of the fan pulley onto the shaft and thread the three 5mm bolts by hand first.
Do you need to change the V belt on a 993?
Changing the V belts on a 993 can be daunting. It’s not the most fun of maintenance tasks, but it is critical in making sure that your air-cooled engine can keep driving that fan to keep itself cool. It’s also essential for making sure you keep the belt’s driven accessories operating like they should.
Why is the alternator not charging the battery?
The car is shutting off because it had ben running off the battery until there is not enough juice left in the battery. So ya, gonna have to check the wire that runs to the battery from the alternator & the small wire that plugs into the alternator. Lot of times that plugin will go bad. 41 people found this helpful.
What to do if your Ford F-150 alternator is not charging?
Ford Dealer gave up after 3 weeks… had to pay $200 for them to find nothing…and had me take truck back.; 17 people found this helpful. Check voltage drop on red cable from battery to alternator and also do an alternator ripple test.
An automotive alternator is a device that converts power from the engine into electricity, which is used to charge the car’s battery. In some cases, however, the alternator can actually drain the battery, causing significant problems. Insufficient Alternator Voltage An alternator that’s not providing enough power can allow a battery to run down.
What to do if your alternator isn’t working?
Although it seems to be working, make sure that the Battery warning light is lit up when the key is set to ON with the engine not started.
Is the alternator good for a new battery?
We tested the new battery (meter test and cell test) which tested like a new battery should. The alternator also showed that it was charging the battery. All of the connections are clean of corrosion and tight. All of the fuses are good.
If you’re not 100% sure, you can use a multimeter, or a voltmeter, to check the current coming from your battery. Attach the positive lead to the positive battery terminal, that’s the red one, and then the negative leave it to the black terminal. With the engine off you should be getting a reading of 12.5 volts on your multimeter.
How to bench test an alternator on a boat?
Before you do that, you need to excite it otherwise it won’t charge by wiring a bulb across the warning light terminal. What amazes me is why electrical engineers and engineers don’t test alternators on the boat where sometimes the fault lies in other areas than the alternator itself .
You can easily test the voltage by connecting a voltmeter to your battery while the engine is off. The voltage reading should be between 12 and 13 volts. You can automatically assume there’s a battery problem when the reading is lower.
https://www.youtube.com/watch?v=m1y1FO1EeiEWhere is the PCM located on a Dodge alternator?
This is where the PCM lives behind your air filter box, notice I removed mine for better access, TURN THE KEY OFF before disconnecting. The connector closest to the passenger side is the Grey C3 connector. The Connector in the middle is the White C2 connector. Reference the wiring diagram at the PCM.
How to test the voltage of a Dodge alternator?
There should be a connection between these two pins. Next test the Pin 10 of the White C2 connector to the GREEN wire pin at the alternator plug. There should be a connection between these two pins.
What kind of battery does a Caterpillar excavator use?
1585723 BATTERY & WIRING GROUP – MINI HYDRAULIC EXCAVATOR Caterpillar 303.5 – 303.5 Mini Hydraulic Excavator DCH00001-UP (MACHINE) POWERED BY 3013 Engine ELECTRICAL AND STARTING SYSTEM | 777parts ALL PARTS, INC. We sell new, used and rebuilt parts for construction equipment.
Is it safe to turn on heated windshield alternator?
But don’t turn on the heated windshield if your vehicle has one; alternator voltage may increase to over 100V and this can be unsafe. Take a voltage reading across the battery posts. Your reading should be at least 0.5 volts above base voltage for your system to keep up with electrical system demands.
How much does it cost to replace an alternator?
Alternator Prices and Installation. Make sure that your current alternator is beyond repair first before getting a new one. Alternator prices can vary greatly by make and model, but generally speaking, new alternators should run around $250 without labor for installation.
What to do if your alternator has low voltage?
Put the black multimeter probe on the negative battery terminal (if possible dig it into the battery post, not the terminal). Put the red probe on the alternator case. Your looking for the voltage to be below about 0.5v. If the voltage is higher than that examine all the negative cabling for problems. Preform the same test with the positive side.
What to do if your Vanagon won’t start?
A Vanagon Stalls and Won’t Start. I have had people email me with this problem about a million times so I finally decided to do a web page about the proper proceedure to get your van up and running again. GOT GAS? First of all, do you have gas in the tank?
When do you need to replace the ECU in Vanagon?
Many times it is the ECU that has failed and needs to be replaced. Any ECU from 86-91 will work in any other 2.1l Vanagon so if you have a friend nearby that is willing to let you borrow his ECU this is the best way to test. If you have to guess I would say that most of the time it is the ECU.
Why does my alternator warning light keep coming on?
When the light stays on, it indicates that the computer has detected an issue with the charging system. If this light illuminates, try to use only necessary accessories like windshield wipers or headlights so as to avoid excessively draining out the battery.
What causes the battery light to go out?
Click to expand… Many charging systems put the alternator energizer wire through the light bulb. When the alternator starts charging positive voltage is equal on both sides of the bulb filament and the light goes out.
What to do when your alternator stops working on your car?
After running the motor for a while, turn the car off. If you can’t get it to restart, this is a sign the alternator is doing its job of keeping the battery working while the motor is running, but the battery isn’t retaining the charge when the alternator has stopped. The car battery could be old.
What causes battery light to stay on while charging?
Alternator problems can cause your battery lights to stay on while charging. Some indications of these problems are dim headlights, ‘charge,’ and ‘alt’ indicators light up. The battery needs copious water to operate, hard or slow to crank the engine, and alternator noises.
What happens when the dashboard battery light comes on?
Your car can often run normally even if the dashboard battery light comes on because the car is capable of running off the energy that is already stored in its battery. The car, therefore, carries on running perfectly until its battery runs flat. After that, none of the car’s components will work.
Why is my battery not charging on my VW?
Vw confimed no issues with discharge. My complaint is non-professional method to charge battery. It isnt smart because, with low battety condition it doesnt charge battery unless (A). Vw dealers are hiding this issue. Hi yes my battery was a moll replaced with a varta.
What should the voltage of the alternator be?
What is the output of your alternator? Battery voltage measured at the terminals with the engine running should be about 13.7-14.7 volts. That is the output of the alternator at the battery and that range is needed to keep the battery properly-maintained.
Indicator Light On Usually, the first sign that your charging system is in trouble is a “battery,” “ALT,” or “CHARGE” warning light illuminating on your instrument panel while driving. It means that the alternator voltage output is below 12 volts, or over its limit or has stopped charging the battery and your car is running on battery power.