Could someone give me some electrical advice please. I have a 14' hydraulic dump trailer and I want to be able to charge the hydraulic pump battery when the trailer is hooked up to my truck while driving. Currently I have to hook the 12v battery that is located in the box on the front of the trailer to a charger in order to keep my battery for the trailer charged up. I can probably use the hydraulic pump about 6-7 times before I have to head home to charge it up on the charger. The hydraulic rams are powered up and down so it takes a toll on the trailer battery. There is a 12v deep cycle battery being used as the power source for the hydraulic pump to raise and lower the dump bed. On my 7 pin trailer connector there is a slot open for straight 12v supply...all the other connectors on the 7 pin are used for the lights and trailer brakes. Can I use this 12v source coming off the 7 pin connector located on the rear of my truck, and run the wire from the trailer side of the connector to charge my battery while I am driving?..or is there too much of a current draw on the wiring. If this isn't possible do I need to run a heavy guage wire from my battery on the truck back to the battery on the trailer and use some kind of connector to join the two together? If so what guage wire and any suggestions on connectors. Thanks in advance..I know this was long but I needed to try to explain as best I could. The truck is a 05 Ford F350 PSD w/dual batteries.

 

First, check that power wire on your plug and make sure it does have power. If it does, I would go ahead and hook the trailer battery to the proper place on the trailer plug so it can get the power from the truck plug. You may have to turn the key on in the truck for it to power up. I don't think you will have a problem with the fuse blowing unless the trailer battery is extremely dead.

If the truck plug power is dead, make sure it has a wire going to it. If it does, then go up front into the fuse box under the hood, and see if you can find a spot in there for trailer aux power. The fuse may not be installed.

If the plug is not wired up on the truck, then yes, you can run a short piece of wire from the battery + to a 30 amp circuit breaker. Then run a 10 gauge wire to a small 30 amp foglamp relay that you can buy at the parts store, and go buy a on-off switch. Then run the wire all the way to the rear and insert it into the extra spot on the truck plug.

The switch or the relay will turn the power off to the rear battery, so it will not drain your truck battery when the engine is not running.

 

problem solved .
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