Re: Flat battery today ...alternator? [message #370483 is a reply to message #370482] |
Mon, 12 September 2022 10:05 |
boybach
Messages: 566 Registered: December 2020 Location: Vancouver Island
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Hey thanks Bruce - Makes sense. I knew the isolator wasn't a "smart" device so couldn't figure out why it could be "regulating" the supply to the chassis battery. At the moment Canadian tire doesn't stock any but Princess Auto is carrying a 90 amp model ..that one looks physically identical to what's on board right now so I'll pick one up this morning.
Thanks again
Larry
RF_Burns wrote on Mon, 12 September 2022 05:49Larry,
An Isolator allows current to flow from the center post (Alternator) to the outer posts (Chassis and House batteries). It blocks current from flowing from the battery terminals to the alternator or to each other. Therefore the house loads cannot discharge the chassis battery, but the alternator can charge both batteries.
Since you see ~15 volts at the center post (alternator) but less than 12 volts on the chassis side, that indicates to me that the Isolator is faulty. The battery terminals should be about 0.7 volts lower than the alternator terminal with the engine running. That's the only test you really need to indicate a good/bad isolator.
Isolators are widely available, I'd suggest Princess Automotive or Canadian Tire for us Canadians. Get one rated at at least 90 Amps, 120 or 150 amp models give you some more robustness.
The center terminal is generally the Alternator. It doesn't matter which battery connects to the other two terminals.
Larry - Victoria BC -
1977 ex-Palm Beach "Ol' Leaky" 40,000 miles, PO said everything working but forgot the word NOT. Atwood helium fridge, water heater & furnace. SS exhaust system, Onan, Iota Converter, R134A, New fuel lines & heat exchange hoses
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