"WATER HEATER BLUES" - Check your battery charge...

[Greywolf]

This all came out of an issue with a water heater (as you can tell) but what it boiled down to was that the man had a bad converter (120 A/C to 12VDC) in an old RV. It also had a disconnected relay from the alternator - so nothing was coming from anywhere to charge this poor guys RV battery... We put a new battery in it, and it worked fine in the shop. OKAY so far... Fella came to pick it up, and the ding-dong thing would not stay LIT! So now I'm wondering, and called over our lead tech - because I knew it worked fine not one day ago. What we had done was clean the burner tube and the gas orifice, after that it was fine. Getting down to brass tacks, what "Billy" had to say was that if the battery voltage drops too low, the gas solenoid that controls the flow to the burner jet doesn't have enough voltage to open up all the way - so the flame sputters and goes out! Less than 10.5 volts, and it will do that. We read the battery - it read 8.01.... This led us onto rewiring the relay from the alternator (we found it with all of the wires hanging down disconnected) and then traced the convertor wires as well. The convertor was sending 12V out to lights and things, but not to the RV battery. Reason? The battery leads were connected backwards. Go figure what it did to that side of the convertor.... OH YEAH! There is a dedicated circuit inside that convertor that does NOTHING EXCEPT charge that battery. So here what I mean to say is keep an eye on your battery charge. The RV battery should be read with nothing connected, and it will read 12.5 at best. AS SOON AS YOU CONNECT SHORE POWER it should read 13.75 or so, which tells you it is being charged by your convertor. If it is not connected to shore power, and the engine is running - it should read 13.75. This means it is getting power from the alternator. If the generator is running - it sends juice to the convertor, and the convertor then sends (you guessed it!) 13.75 to the battery... If any of this fails, it can kill that RV battery. I hope I have given you enough here to check it. You WILL need a voltmeter. ~Wolfie PS: I highly recommend that if your coach does not already have a battery disconnect switch right next to your battery, that you install one or have one put in. An actual, physical "reach in there and turn it by hand" switch. Trust me on that. PPS: The ground wires in RV's are normally WHITE. I personally thought that was exactly backwards - but you will find that it is true. PPPS: Also be aware of two things if you have a generator: If it runs on gasoline, and your gas tank is less than a quarter tank - YOU CAN'T START THE GENERATOR. It won't let you. They are made that way so the generator does not run you out of gas. Secondly - if the generator does not "SEE" some voltage at the battery, it won't start. You can get over this sometimes by hitting the "AUX" battery switch to cut in your fully (?) charged engine battery. ONAN generators are wired to cut out if they sense that "There isn't anything there".