Batteries Overcharging Badly

[davidbrady]

Chuck, great questions and I completely agree about replacing all the batteries in a bank when renewing batteries. Many years ago when I bought my coach from Parliament Coach they told me when they prepare a coach for sale it automatically gets all new batteries. They're convinced that the money spent upfront is ultimately less than the money spent on techs chasing a variety of ailments most of which turned out to be related to faulty batteries.

Mike,

Here's a wild guess. Since the tech isn't a Wanderlodge expert it's possible that he may not have wired things up properly. You said he replaced a solenoid. I suspect the solenoid he replaced is the 'aux batt' solenoid. There are two diodes on that solenoid (actually three but one is for flyback current) that allow the dash switch or the engine start circuitry to enable the 'aux batt' solenoid.

If he failed to wire in the diodes or if they're reverse biased then the solenoid won't be turned on as it should. When the engine is started the chassis batteries act thru one of the diodes to turn on the solenoid thereby connecting the house battery to the chassis battery banks.

Here's what I'm thinking. The 50DN alternator sense wire may be wired to the chassis batteries, but the alternator charges the chassis batteries thru the 'aux batt' solenoid. If the solenoid isn't automatically activated while you're driving (aux batt LED on the dash is off), then the 50DN is always reading a low voltage. Since it's reading low, the 50DN voltage regulator cranks up the field current which results in the 50DN putting out excessive voltage. Guess where all this voltage is going? That's right, to the house battery bank. In short, your 50DN may be boiling your house bank because it's using the chassis bank to sense voltage but the chassis and house banks aren't connected due to incorrect or missing circuitry at the 'aux batt' solenoid; hence, all the 50DN power is going to the house bank with no voltage regulator feedback.