Shore power donor

[Edit:  the idea of minimizing wiring losses is central to this idea.  So central that, like a fish is unaware of water, I forgot to mention it at all.  Thanks to the commenter for pointing this out.  Clarifications in orange below.]

I’ve been thinking about this for a few months but finally wrote it out in response to a question on CRVL.

In this model we are, in effect, making the tow vehicle a shore power donor.   How it could work:

  1. Place solar panels on the tow vehicle’s (TV)  roof rack and carries battery bank in the bed under a camper shell.

  2. Run a small inverter (enough to run normal trailer loads) and an extension cord to the trailer’s converter).  This minimizes wiring losses by inverting to a much higher voltage.

  3. When not separated by distance use a heavy 12v umbillical.  This eliminates inversion losses when distances are short.

  4. Heavy trailer loads would wait until vehicles were rejoined or be run from the tow vehicle directly.


**Pro:  **

  • main battery bank resides in a towing vehicle more suited to carry them, and the weight could be placed over rear wheels for added 2wd traction.

  • Setup allows for 4wd, generally unavailable in vans.

  • Bank could potentially be larger in this configuration since not so limited by packaging or weight.

  • Banks easier to vent in camper top.

  • More room for panels on TV rack.

  • TV can be located in clearing for direct sunlight.

  • Panels (and power) stay with vehicle if you need to run to town.  You can still use truck as short-term camper if needed.

  • Trailer retains normal house battery so can still function in absence of TV if it is in for service.

  • Could use TV as donor vehicle to help other boondockers in emergencies


  • Wiring losses

  • Expected to be generally inefficient due to losses both in inverter and converter.  to power trailer through it’s converter.

    • Minimize this by using smallest and most efficient inverter appropriate.

    • overpanel using generous TV rack?

  • would have to be careful not to turn on heavy loads that real shore power could handle:  microwave, A/C, etc.