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Friday, October 30, 2009

No Electrical Power

I cannot figure out why I have no electrical power in my motorhome when trying to run off the battery, (I have two batteries). I have an older Eldorado on a Chevrolet chassis. When you plug it into a generator or shoreline power everything works, but when I try to run off the battery, nothing works. The original owner took the existing onboard generator out. Could this be the problem of not having electrical power? I have flipped over the 12-volt switch and it did not make a difference. I have no owner’s manual to the motor home. Are there any breaker switches or fuses that can be checked? I have checked all over the Internet for help on my motorhome and can find nothing. Thank you in advance for any help you may be able to supply me with.
Kim, (Philipsburg, PA)

Kim, I am assuming you are referring to the 12-volts DC power for the lights, water pump, etc., when you say “no electrical power.” If you are expecting the standard, house-type receptacles to be powered, remember, those only work when connected to 120-volts AC. The roof air conditioner and the electric side of the refrigerator, for instance, all operate on Alternating Current. The batteries only produce Direct Current for low voltage applications. I only mention this because of the age of your motorhome. 

I'm guessing yours is equipped with the, now obsolete, dual voltage system; meaning each lamp will contain a 12-volt DC bulb (when operating off battery) AND an additional 120-volt AC bulb (when plugged into shoreline or when on the generator). But because you also mention a switch, I'm thinking you have low voltage lamps along with other DC loads such as a 12-volt water pump to be run off the batteries or powered by a converter when AC is available. If that is the case, your converter appears to be operating properly because you do have DC while plugged in. It's my opinion you either have a faulty manual switch that switches the DC power from converter to the batteries or the battery wiring is incorrect or you have lost a ground somewhere. 

Be sure the batteries are properly grounded to the chassis of the RV. The switch can easily be tested by an RV technician using on Ohmmeter with the AC power disconnected. During that era, it was usually located at or near the converter itself. If it checks out fine, further troubleshooting is in order to find the wiring dilemma. If the batteries have recently been installed or connected, I'd start there and work my way to the battery/converter switch.


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