A few days ago, my 97 Corolla had trouble starting. It cranks but doesn't start, maybe due to a problem with the carburetor. Figured I might discharge the battery, so I stopped my attempts at starting. Fast forward to this morning, I tried to start the car, but it had difficulty cranking, it was barely able to spin the pulley and was making a clicking noise. I measured and it was 10.5V.

I went to charge it with a 10 amp 12 v charger for like 8 hrs. I took a reading immediately after charging and it read 12.9V

I let the battery rest down, unconnected to the car, for 3 hours and when I checked, the voltage was back down to 10.5!

Is my battery busted? Should I try charging it for a longer time?

  • Welcome to Motor Vehicle Maintenance & Repair! Jul 16, 2020 at 12:16

1 Answer 1


Yes, this is a bad battery. One of the cells has most likely shorted. Each cell is a little above 2vdc. A fully charged battery will usually be ~13vdc. If you lose one cell, it will drop it down ~2vdc, which puts it right down in the arena of 10.5vdc. A direct short inside of a cell will allow electrons to pass through the short instead of raising the voltage, which is the reason you're still reading the 10.5vdc. Anyway, long story short: you need to replace your battery.

  • 2
    To add, car batteries don't last forever and this is the most typical way for them to die. Decades ago the typical lifetime of a car battery would be two years, today you can expect 7 - 10 years from a good Exide or Varta in your '97 car, and possibly as little as two years again from the deep cycle type battery in a modern car with mileage-optimized charging and active stop-start system.
    – Pavel
    Jul 17, 2020 at 9:18
  • To determine the age of your battery, follow the steps outlined in this answer to read the date stamp. mechanics.stackexchange.com/a/70106/45516 Jul 17, 2020 at 16:43
  • Yep, this is classic dead/shorted cell. If the rest of the cells are good you can probably charge it up to 12.5 V by severely overcharging them (most chargers will happily do this), but the voltage will slowly drop back down to around 10.5 or so after being removed from the charger. Jul 17, 2020 at 21:32

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