Battery question

Jul 23, 2008 3 Replies
I

Two identical RV batteries. They have been unhooked from the RV 'converter' (smart trickle charger) for 5 days. Checking with a hydrometer shows that all cells are 75% charged. (12 cells, two batteries). HOWEVER one of the batteries reads 12.35 volts while the other reads 8.6 volts. Why this discrepancy when the hydrometer readings are identical? Obviously, I will replace the low voltage battery, but, I want to learn why the hydrometer readings are in discrepancy with the voltage readings. BTW, checked the voltmeter against my truck battery (everyday use). It reads



13.2 volts with the engine not running.

Thanks for all replies,



Ivan Vegvary


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B

if the batteries are roughly the same age then it would be best to replace both at once. I recall some time ago I spoke with a diesel mechanic. He said on the big diesel trucks they use 4 batteries. they replace all 4 at once.

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S

Sounds like it has a couple shorted cells.

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D

Yep - The low voltage is close enough to perfect for what you'd expect to see with exactly two shorted cells.

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