So a few months back I bought an a battery for my 4runner and it has been working great. Its winter now so it's been sitting outsidefor about a month and has been cold down to 10f at night. I go to unlock it and and nothing. I manually open the door put the key in and zero lights come on! I jump start the car move it and now the battery is on a battery tender. Have I damaged its charging potential? Have I caused some kind of permanent damage? I have a winch hooked up to it nothing else. This ruins my day a bit.
Did I just ruin my new agm battery
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riceandpho
Elite Member
have to use a multi meter to determine the voltage of the battery first, if its below 12, use a charger to wake it up, then itll charge it back up to the proper voltage. charger with agm mode will try to charge at 14.3 to 14.7v, depending on the charger, itll bring the battery back to full if it holds charge.
Disclaimer first, I am not an expert when it comes to batteries. That being said, I have recently purchased an AGM battery for my starter battery and am looking at purchasing a deep cycle hybrid for my dual battery set up. Charging AGM batteries can be tricky in cars that weren't designed to charge them. AGM batteries require a higher charging voltage and different charging profile than your standard lead acid battery. Since your battery is somewhat new I would make sure to have your battery tested to see if there isn't a draw on it when the vehicle is turned off. If you do decide to get a battery tender/charger make sure it is compatible with AGM batteries to get the proper charging voltage and charging profile. My two cents.
Bumbo
New member
You really need a muitimeter / volt meter. Take a reading of the battery (before recovery charging) to determine the voltage of the battery when it was dead.
That would have given you a much better indication of how far it was pushed into the ground.
The low voltage is one thing, but the longer the duration is actually a bigger concern.
At this stage all you can do it charge it and monitor it to see how it does. You can always get it tested to CCA as well.
Edit:
I feel good lead batteries can be resilient, and can handle a couple deep discharges without too much degradation. If I suspect a battery is low I always measure it first and decide what to do. If it is dangerously low, I never crank the engine and put a load on the battery; I have actually internally shorted a battery doing this making it unusable. I have also recovered batteries from very deep discharge with minimal issues, and they go back into service like normal.
That would have given you a much better indication of how far it was pushed into the ground.
The low voltage is one thing, but the longer the duration is actually a bigger concern.
At this stage all you can do it charge it and monitor it to see how it does. You can always get it tested to CCA as well.
Edit:
I feel good lead batteries can be resilient, and can handle a couple deep discharges without too much degradation. If I suspect a battery is low I always measure it first and decide what to do. If it is dangerously low, I never crank the engine and put a load on the battery; I have actually internally shorted a battery doing this making it unusable. I have also recovered batteries from very deep discharge with minimal issues, and they go back into service like normal.
Last edited:
superman3043
Senior Member
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