I have a "Toyota True Start" battery in a second hand 4Runner. It looks like the battery is about 4 years old. It has been run dead a few times. Once a light was left on that killed it to basically 0 volts, totally dead. I've always been able to jump start it and charge it up by driving around normally and it's fine. Until now.
It was recently run dead and after a jump start was only showing 10.5 volts, suggesting a dead cell. It required a charger to get it back to life. My small 1.2A charger took over 24 hours but it did bring it back to 12.6 volts. It worked well for a while. Then I let the truck sit for a few days, cold weather came and the battery was again dead.
I put it on charge again, thinking it might fix some sulfation and bring it back to life. After letting it charge for almost 24 hours, it was full, then I let it sit for 12 hours, all at room temperature and it was still showing 12.6 volts. Maybe it's fine again?
I tried load testing it in the truck by turning on every electrical device I could (key on, engine off) and saw the volts drop to 12.1, but after 10 minutes they stayed steady. Cranking the engine it looks like they fall to about 9.7 but the engine starts too fast for the meter to stabilize and I can't tell what it bottoms at. I started it over and again about 6 times in rapid succession, no time to recharge, and it still seemed to turn over ok.
Is 9.6 volts too low? I don't trust my local shop to load test it, I think they'd tell me a brand new battery failed their load tester.
It was recently run dead and after a jump start was only showing 10.5 volts, suggesting a dead cell. It required a charger to get it back to life. My small 1.2A charger took over 24 hours but it did bring it back to 12.6 volts. It worked well for a while. Then I let the truck sit for a few days, cold weather came and the battery was again dead.
I put it on charge again, thinking it might fix some sulfation and bring it back to life. After letting it charge for almost 24 hours, it was full, then I let it sit for 12 hours, all at room temperature and it was still showing 12.6 volts. Maybe it's fine again?
I tried load testing it in the truck by turning on every electrical device I could (key on, engine off) and saw the volts drop to 12.1, but after 10 minutes they stayed steady. Cranking the engine it looks like they fall to about 9.7 but the engine starts too fast for the meter to stabilize and I can't tell what it bottoms at. I started it over and again about 6 times in rapid succession, no time to recharge, and it still seemed to turn over ok.
Is 9.6 volts too low? I don't trust my local shop to load test it, I think they'd tell me a brand new battery failed their load tester.
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