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

 

Con:

• 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.