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I wouldn't go monkeying with a boost converter. The stock system, when working properly, does a decent job of charging both batteries. If your house battery isn't charging well, then there is a problem somewhere in the system. The boost converter will only mask the problem and adds in another possible failure point. Is it possible for this thing to fail and put out 80v as a result? I dunno. I would focus on analyzing and fixing the system. I would first test the alternator to make sure that it is putting out a good voltage under load with the house battery disconnected from the system. I saw an email just a couple days ago about this on this listserve. If the alternator checks out healthy, reconnect the house battery & compare the charging voltage at the car battery to the voltages into & out of the relay and at the house battery terminal. Those voltages should all be pretty close & a significant discrepancy will point out what item needs attention. I have a Riviera and they came with the Surepower isolator. I really like it, but I don't think that there's any fancy voltage boosting circuitry in it; just basically some heavily heatsinked diodes for the isolation and a feedback signal to the alternator to boost voltage enough to compensate for the voltage drop caused by the diodes. Standard automotive batteries only last 4-5 years, and you say that this battery is a few years old, so it's probably getting towards the end of it's lifespan. They are designed to put out a high current for a few seconds, and then be immediately recharged. Used as a house battery, they face long periods of time in a state of partial discharge, which is not healthy for them. The house battery on Albert is going on 5 years, and it's capacity is much lower than it was the first couple of years; I'll be getting a new one before next summer. Also, if you're running the fridge while driving, that puts a big load on the alternator, especially if the headlights are on, and slows the rate of recharging the batteries while driving.
Brett
-- Brett in Portland, OR "Albert" '82 VanaFox I4 Riviera |
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