Trailer Fuse Blows When Two Series-Wired 6V Batteries are Connected

Question:

Had 2 12 volt batteries and I changed to two 6 volt batteries. I have them wire in in sequence but I keep blowing my 15 amp fuse inside the trailer

asked by: Colby

Helpful Expert Reply:

A single 12V battery can be replaced with two 6V batteries that are wired in series. This wiring arrangement is shown in the linked image. Two 12V batteries in series produce 24 volts; two 6V batteries in series produce 12 volts.

If the batteries are wired in series, the positive terminal of one battery will be connected to the negative terminal of the other. This would double the output of the batteries, so two 6V batteries wired in series would provide 12 volts of output. Current capacity does not increase.

The fuse in your trailer power box blowing could be a result of a short in the wiring or from the trailer's various electrical items drawing too much power for the amperage (current) rating of the batteries. They will have the correct voltage (12V) when series-connected but the batteries may not have the CURRENT capacity for all appliances and devices inside the trailer. Check the total current drawn by the trailer and compare this to the current amp-hour rating of the two 6V batteries.

expert reply by: Adam R