12 Volt Toad Charge Line

[billkoboldt]

In the Sept 2012 issue of Family Motorcoach, there was an article about running a 12 volt charge line to keep the towed cars battery charged, also in the last two issues in Tech Talk this was addressed. They all said to run the line from the coach battery. Why can't I run a wire from the 7 way trailer connector from the hot terminal in the connector to the towed cars battery. I also assume I would need to run a ground wire from the connecter to the negative side of the towed cars battery. The motorhome has a 7 way connector that I use for connecting the lights to the towed car. The 7 way connector has a hot terminal and a ground terminal. I will be using 8 gauge wire for the set-up along with a 20 amp in-line fuse on the positive wire.

[wolfe10]

What you are suggesting MIGHT work. The issue will be how much voltage drop between coach chassis battery, chassis battery terminal of battery isolator, etc and that 7 pin connector. If a short run of 8 gauge wire, likely no issue at all. You will need to measure voltage at the coach chassis battery and again at the 7 pin while it is charging toward the higher end of your toad's amp needs. Said another way, under no load, voltage will all read the same. The more resistance (small gauge wire, longer run, more connections) AND the higher the amps you are transferring, the more the voltage drop.

Same for your ground connection between the vehicles.

Be sure to put a fuse at BOTH batteries, as both ends of that charge wire are HOT.

Brett

[billkoboldt]

I don't know if we are on the same track. My motorhome was wired from the factory with a 7 pin trailer connector. I plug into this for tail and turn signals on the towed car. It has a pin that is hot all the time and also a ground pin. All I would do is add another wire to the car end of the plug to go to the positive side of the battery and one to the ground side. That way it seems to me it would charge the towed car from the starting battery of the motorhome as I am driving.I know I would have to put an in-line fuse between the car battery and the connector on the motorhome. The length of the two wires would be about 6 to 7 feet long.

[wolfe10]

Understand.

But, not all factory wired 7 pin charge wires are the same. You certainly have nothing to loose by wiring your toad to it (with fuse at toad battery).

If it doesn't do an adequate job of keeping the battery up, you can always upgrade the coach end.

[desertdeals69]

Be sure to check the wire size of the ground.

[taylorgso]

The Toad Charge system has some safety features that a direct wire would not have. At the Motorhome end, there is a charge controller, that regulates the input to the toad, and is fused at both ends with a breaker in the toad, and in the charge controller.

[ticat900]

It is completely correct to run a 10-12 gauge wire from chassis battery to the 7 pole connector through it and up to the toad battery

that works just fine. Been there and do that. I put a 20amp circuit breaker on each end. It will charge 100% fine run the same size ground wire also 10-12 gauge. I like 10 gauge.

If you have and want to use the factory wired 12V supply line in the 7 pole connector that will suffice also.

I have looked at the charge controller and its exspensive.Your alternater regulater should suffice although I suppose its possible to boil your toad battery.I make sure my line is only connected when toad motor is off and in tow position(ign on) does not overcharge

at all

[srfridley]

My 2006 Winnebago (freightliner) has a 7 pin connector with a 20 amp pin that is hot when the MH ignition is on. This pin is fused on the MH side. I have used this to power a toad charger (the system with diodes) for years with good results. I tow an Acura MDX that has a Navigation system and use a brake buddy braking system and have had no toad battery issues. Without the toad charge system my car battery would be dead after about 4 hours of towing.