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Popsie's avatar
Popsie
Explorer
Sep 07, 2013

Charging Toad battery with 4-wire harness?

I just posted a comment to the "charge lead from motorhome to toed" topic, and it got me thinking.

I belive that the 4-wire harness has conductors for ground, tail lights, left stop/brake, and right stop/brake.

Now, suppose:

At the toad end of the 4-wire harness, you splice a wire to the tail lights conductor, then connect it to a diode (oriented to allow the current to flow from the tail lights conductor), then through a 10amp fuse then to the positive battery terminal.

When driving with the running/parking lights switched ON, current would flow from the tow vehicle alternator/battery - through the tail lights conductor, through the diode and fuse, and into the positive terminal of the battery to keep it charged up. Of course, the toad tail lights would also be on.

Does that make sense?

3 Replies

  • Here is how it Can work. Install a 12 volt tail light bulb somewhere under the hood and in series with your wire. The bulb will limit the current to the battery and supply enough to keep it up. As the toad battery gets closer to being full the bulb will dim or go completely dark.

    I have done this as a poor mans trik-l-start between two battery banks in a previous MH. The Invisibrake toad brake uses the tail light wire to tap off about 2 amps. I have not opened it to see how it restricts current but a bulb is a cheap and easy solution.
  • sch911 wrote:
    No. The running light circuit is most definitely not sized for that level of current draw on the MH side. Run a separate wire to the battery. Or as others have done have it converted to a 7 way plug which contains a charge line.


    X2
  • No. The running light circuit is most definitely not sized for that level of current draw on the MH side. Run a separate wire to the battery. Or as others have done have it converted to a 7 way plug which contains a charge line.

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