How to diagnose a car generator yourself in a couple of minutes

With a properly functioning generator, the battery will last as long as possible. If he does not fully charge the battery, then sulfation occurs in it, which causes it to quickly fail, and when recharging, the electrolyte in it boils away. To prevent the battery from deteriorating, the generator must produce a charge within a certain range. You can check all these parameters yourself without the help of an auto electrician.

Generator self-diagnosis process

The test must be carried out on a vehicle that has been parked without starting the engine for at least 12 hours. By using multimeter You need to measure the voltage at the battery terminals. It should be at least 12.5 V. Ideally, the voltage is in the range of 12.7-13V. If it is within 12.5-12.7, then this means that the battery is either not fully charged or has already begun to degrade. At lower voltages, it is imperative to do a full check of the generator, especially if the battery is relatively new and should not yet fail.

After the first measurement, you need to start the engine, and with the engine running, measure the voltage at the battery terminals.In this case, all electrical consumers must be turned off. The voltage of a properly operating generator will be in the range of 14.2-14.6 V. If without load it is lower or higher, then it clearly has a malfunction.

Next, you need to let the engine warm up and turn on all electrical consumers in the car. These are primarily lights, heater, air conditioning, heated seats, radio, etc.

In this mode, the voltage on the battery when the engine is running hot should not drop below 13 V. If it is lower, this means that the generator does not have enough power to fully charge the battery.

If the generator cannot cope, then the voltage regulator may be faulty. Worn brushes or slip rings may also be the cause. In this case, the voltage at the generator constantly jumps.

In this simple way you can check the operation of the generator and evaluate how correctly it charges the battery. If it does not pass the test, it must be repaired. As a rule, this is much cheaper than replacing damaged batteries every 1-2 years.