# of watts solar system needed to MAINTAIN coach batteries?

Jim@HiTek wrote:
I know that in my Class A rig the chassis battery draw is much, much more than 100mW (0.1 Watt). It's more like 12 Watt even with the salesman's switches 'Off'.

The draws are to the dash, which supplies the radio memory, the CO detector, and the propane leak detector. Then the steps, also stay powered. Some newer class A rigs have both a computerized tranni and engine which have memories that are, again, kept powered even with the salesman's switches 'Off'.

I think you have a unique rig if yours only draws 100mW while just sitting.

Wow! 12 watts seems surprisingly high. Besides my own measurement at 50mW, the 100mW figure comes from this old rvdoctor.com article (http://www.rvdoctor.com/2009/12/which-circuit.html). And drawing at 12 watts (roughly 1 amp!) would drain my batteries in less than 3 days and that sure doesn't happen.

I assume you've measured the draw, but did you wait for equipment to go into sleep mode? I assume you know this, but when you energize the circuit by reconnecting the battery through the ammeter, lots of the onboard stuff goes into start-up mode where it draws much more current, and it takes several minutes for everything to go back to sleep. If your 12-watt measurement is after everything has settled down, I never would have expected that.

P.S. Great blog! I hope to get back to the Northwest sometime next year, and your posts are definitely encouraging me to make the trip.