Chassis battery drain **solved **
This goes under the catagory "Don't have your alternator serviced by someone not familiar with the RV battery isolator"
After we got our 1991 coach last summer one of the first things we noticed was the chassis battery was going down overnight. In fact one morning we actually needed a jump to get started. (A compounding problem was the boost relay was not working which prevented connecting the batteries together - I have also fixed this). I also was aware that in the coach's previous life the alternator was replaced with a re-built 130 amp - smaller than the stock 160 amp - probably to save money. I have purchased a new 180 amp alternator which I will be installing this spring.
I found the battery drain problem, see photo. Someone had put a jumper wire on the battery isolator between the center alternator post and the chassis battery post. With the ignition key off, there is no voltage present on the alternator positive terminal due to the battery isolator in the circuit. Someone not familiar with the RV assumed that is a problem that needed to be fixed - as the alternator needs voltage at the positive terminal to function. What they didn't understand is that on this Foretravel model (1991) voltage is applied through a diode to the alternator positive terminal when the ignition key is turned on, which allows the alternator to function properly.
Topic: Chassis battery drain **solved **