Does a frown of worry ever cross your face when you start your auto on a winter morning? Perhaps it should, if your starter battery is getting older. Lead auto starter batteries do not last forever because they wear out eventually. However, we can keep them going longer if we treat them with respect.
Design Assumptions Behind Auto Starter Batteries
Auto lead acid starter batteries have two basic functions to perform. These are to deliver a surge of electricity to turn the starter motor over. And to smooth the power coming from the alternator and feeding the accessory circuits.
Battery manufacturers assume the engine will be running, and charging the battery when the accessories are on. If not, the auto battery starts draining and will eventually run flat. The two big no-no’s are leaving the lights on, or the audio playing after you turn off the motor. Car makers take care of the rest for you. In case you wondered, that is why other circuits go off when you turn off the ignition.
If You Think the Battery is Suspect, Test It with a Voltmeter
Auto starter batteries slowly discharge even with all the circuits turned off. If you go away for a week and the starter is sluggish, you can test it with a voltmeter. Fully charged auto starter batteries should read at least 12.6 volts. Or between 13.7 and 14.7 volts when the engine is running.
The best way to test a battery is to remove it from the auto. And then take it up to full capacity with a battery charger in a well-ventilated space. If you cannot get to at least 12.6 volts, then your battery has a problem. If you charge it to above 12.6 volts, but your lights are a little dim after taking the car for a drive, then your alternator, not your battery has the problem.
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Preview Image: Winter Morning and It’s Cold
