Golden_HVAC wrote:

Hi,

I have a solar isolation meter, and while driving back from the high mountains to test the solar isolation on 320 acres a friend wants to sell, I checked the isolation at 2,000' elevation, and also inside the windshield. Outside the window was about 1,060, while inside was only about 600. So the windshield glass prevents about 40% of the light from coming in, it is three layers, with UV protection plastic liner in the center, that also helps prevent the glass from shattering in a collission.

So your prospective 15 watt panel will be derated to only about 10 watts if inside the glass.

Why not ad a fifth wire from the RV to the toad battery? Then you can get up to 10 amps per hour into the toad battery, if it needs that much. You would need about 30' of #10 wire and two automatic reset circuit breakers rated at 20 amps. Put one circuit breaker near each battery, then run the #10 wire to the bumper, and then have some sort of connector for the two wires. I used a cheap extension cord on my car, it plugs into the back of the motorhome. I only needed a couple of amps to run my braking system, and it only needed one wire.

I also have a cruise control motor, when I apply vacuum, it pulls the cable, pulling on the brakes in the car. $35 and 4 hours labor, sure beats anything sold at the RV place! And nothing to hook up or fiddle with other than the vacuum line and wire when hitching up or unhitching.

Fred.