View Full Version : Trying to troubleshoot electrical issue

12-25-2015, 06:06 PM
Batteries aren't charging well. If no electricity is being used, they will charge very slowly, over a few days, and only up to about 11.5 VDC. Otherwise, no dice. I am plugged into a 50A shore outlet. Converter is rated 50A. Batteries are new.

Simple diagram: http://imgur.com/bRccTqO

Here's what I measured:

With nothing connected to the ac/dc converter, the converter output reads 14.3 VDC.
With only the battery hooked up to the converter, the output reads 12.05V.
With both the battery and the circuit breaker panel hooked up, the converter output reads 11.6V. Obviously not enough to charge the batteries to full capacity.

I don't understand how I can be getting different voltages based on whether or not the breaker panel is connected, since the panel and the battery are in parallel. And why would the converter only be outputting 12.05V if the battery is connected? Anyone have any ideas as to what is going on?

Thanks for any help!

12-25-2015, 08:39 PM
Not sure about any of this since I don't understand 12volt systems well, even tho been messing with them for over 30yrs of RVing. But--I don't think the CB panel is hooked up as you have drawn it. No battery in system, no 12volt from the converter--I believe all 12volt power goes from converter to battery(s) then to CB panel, not to both at same time. Are you sure the converter sends power direct to the CB panel?
What do the battery(s) read when static and disconnected from the converter?
If you are correct with the converter reading at 14.3, then the problem isn't the converter.
Someone else with better knowledge will surely come along to comment.
Welcome to the forum.
Have you read thru the 12volt bible: http://www.marxrv.com/12volt/12volt.htm Part I
http://www.marxrv.com/12volt/12volta.htm Part II

01-01-2016, 12:42 AM
Sounds like a bad battery. Get the battery "Load Tested"

01-02-2016, 02:19 PM
I think Kerry is right. It sounds like the battery is loading down the converter and when you add the CB box the rest of the 12 volt systems in the trailer are loading it farther. Just because the battery is new doesn't mean it is good. I would disconnect the battery from the system and measure the voltage on it. It should be something over 13 volts.
If I found it lower I would try to charge it with a battery charger. If it charges up and holds at over 13 volts then I would start looking for a short in the wiring going to the battery. If it doesn't charge up I would go for a new battery.