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PatrickFisherPr's avatar
PatrickFisherPr
Explorer
Dec 19, 2015

Drawing more than 12 volts off auxiliary battery

I have a 1984 Toyota Sunrader. Under the hood is an auxiliary battery, which charges off the alternator. The auxiliary battery operates my water pump and the furnace. The furnace requires approx...
Seeking Advice
naturist's avatar
naturist
Nomad II
Dec 19, 2015
As others have said, a fully charged battery is only going to read 12.7 or so, and that's only with an open circuit, i.e., nothing connected to it. Either your battery is bad and not able to deliver power in spite of reading fully charged (I had one do that once), or you have a bad/high resistance connection or broken wire somewhere.

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