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.
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.
Why is the voltage reading on my alternator going up?
While watching the voltmeter display, start wiggling wires at the back of the alternator, the battery, and the remote voltage regulator (if there is one). If the voltage reading on the meter display goes up while wiggling one of the wires, you’ve found a bad electrical wire or connection.
What does it mean when battery and alternator don’t match?
Also the voltage at the battery and the voltage at the alternator should be within 0.5v of each other. 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.
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.
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.
While watching the voltmeter display, start wiggling wires at the back of the alternator, the battery, and the remote voltage regulator (if there is one). If the voltage reading on the meter display goes up while wiggling one of the wires, you’ve found a bad electrical wire or connection.
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 low charging voltage cause a battery to over charge?
The battery is a little pickier about its charging voltage. Below 13.8 the battery will not fully charge. If the voltage is to high the battery will charge too quickly and may over charge. Either way high or low charging voltage can lead to battery problems. In order to get maximum battery life proper charging voltage must be maintained.
Why is the battery light on but the alternator is charging?
1 Check for Corrosion. In some car models, the fumes from the regular functions lead to corrosion to collect on the battery terminals. 2 Clean the Car Battery Terminals. If you notice some corrosion or grime around the battery terminals, it might be the reason why the car battery light is still on. 3 Tighten the Battery Clamps. …
Why does my car have a low voltage alternator?
A low battery also may not have enough reserve power to crank the engine, so the vehicle can be stranded until the charging problem can be diagnosed and repaired. Charging problems can be caused by electrical faults in the alternator or voltage regulator, poor wiring connections at the battery or alternator,…
Why does the battery light come on when the alternator is on?
If the battery light is on when the voltage is above 13v then something is still wrong with the alternator as the switch for the light is in the alternator. I had this with a Denso alternator on a 2006 Ody. Installed new alternator and it worked great except after about 20 seconds the battery light came on even though charging voltage was 14.5v.
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.
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.
Where do you put the red lead on an alternator?
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. Highly active question. Earn 10 reputation in order to answer this question.
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.