Lead Acid Battery Question

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pchilds
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Lead Acid Battery Question

My Prius 12 volt battery went dead after sitting for only two days. The dealer charged it and says the battery is good, 34600 miles on the 36000 mile warranty. The battery is rated at 36 ah, I tested it and at C10 I got 13.4 ah to 50% discharge. Is this good for a two year old battery? 26.8 ah at C10 for a 36 ah battery?

marylandbob
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Re: Lead Acid Battery Question

Seems pretty good, but HOW did you charge and test it? I would charge it from a regulated 14 volt supply, thru a 1/2 ohm current-limiting resistor, for 24 hours, then disconnect it, and allow it to sit totally disconnected from everything, at room temperature (60 to 80 degrres F.) for 5 to 7 days, and then run the discharge test. In this manner, I would discover if any internal defect is discharging the battery when idle.---Back to your CAR: What loads are operative when the car sits idle? Have you MEASURED the resting current drawn from the battery while parked? Devices such as cell phones, GPS, alarms, keyless entry/locking systms, and clocks/radios all draw current, perhaps they dischaged your battery?-Bob

Robert M. Curry

pchilds
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Re: Lead Acid Battery Question

Coming back from the dealer, I removed the battery from the car and charged it at the 2 amp setting with my battery charger. It showed charged almost immediately, the dealer said they trickle charged it over night. I will let it set, out of the car, for a week and retest. The car it stock, no added loads, it is normally driven everyday, it wasn't used for two days because, I had to haul stuff with the SUV for those days. I can get a good quality 35 ah AGM battery for under $60 locally, so it is not a big deal. I would just like to make Toyota replace, it if it has failed under warranty.

Philip
2011 Nissan Leaf SL

marylandbob
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Re: Lead Acid Battery Question

You should freshly re-charge the battery afer removing it,(fully charged voltage should be near 14.0 volts, at the instant charging ends) then, when charging is complete, allow it to sit for 5 to 7 days, and re-test it. (after testing, recharge again)--Automotive lead-acid batteries are normally rated at the 20 hour discharge rate, so expect lower capacity at the 10 hour discharge rate.-Bob

Robert M. Curry

pchilds
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Re: Lead Acid Battery Question

Thanks.

Philip
2011 Nissan Leaf SL

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