Propane Furnace won't ignite on batteries

[tcrsolutions]

I have a '95 Scenic Cruiser Diesel Pusher. I noticed last winter that the propane furnace will not ignite on batteries. The blower motor comes on and works just fine, and you can hear the electric igniter try to light (3 times); but all that blows out is cold air. When the generator is on or plugged into shore power, it ignites and works just fine. I assumed it was just the battery voltage was low and that was causing the problem.

Well, we went out over the weekend and I had the same problem; so I decided to get some new batteries yesterday. I hooked them all up and they have an excellent charge and voltage. I attempted to see whether the furnace would work solely off the batteries today and I am having the same problem. Again, it ignites and works just fine when plugged into shore power or the generator is on. Is it possible it is a relay? If so, where is that located? Does anyone have any other suggestions or thoughts to this problem?

Thanks for any suggestions!

Chris