The battery may indeed be good, but it is discharged, typically due to a failed generator. When that happens, the red "Battery" warning light turns on to let you know there's a charging system problem. The place to start is with having the charging system tested and diagnosed. It is real common for this to be an intermittent failure, so to be valid, any testing has to be done while the problem is occurring, otherwise everything will appear to be okay.
You'll find more dandy information in this article:
https://www.2carpros.com/articles/how-to-check-a-car-alternator
If you'd like to start the testing yourself and you have a digital voltmeter, this article might be useful if you need help using it:
https://www.2carpros.com/articles/how-to-use-a-voltmeter
I can help you set it up too, if that will help.
Be aware a jump-start will get your engine started, but it takes some time for the battery to fully recharge. That can take three to four hours on a slow charge with a portable charger. After that, once the battery is fully-charged, if the charging system is dead, you'll only be able to drive about a half hour to an hour before the battery goes dead again, and much less if you need to turn on the head lights. Turn off everything electrical that you can, such as the heater fan and radio. That can get you a few more minutes of driving time.
Portable battery chargers tend to vibrate the plates inside the battery. Lead naturally flakes off those plates as the battery ages. That normally takes about five years, then once that lead builds up high enough in the bottom of the case, it shorts a cell, and the battery must be replaced. Charging the battery at a high rate vibrates the plates harder and hastens that lead flaking off, and that reduces the battery's life. That's why it is always better to charge batteries at the lowest rate the charger will allow. It will take longer, but the battery will last longer before it fails.
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Tuesday, December 8th, 2020 AT 12:27 PM
