Using "auto" mode on fridge, gas kicks on when traveling

Hi! We have a 2012 Sport 16. We use auto mode on fridge when hooked up to electric, and it does not trigger pilot. When we unhook to travel, it goes for gas vs. the battery. We hear the pilot attempting to light several times; no go. So, we end up shutting off while traveling. Shouldn't it switch to battery? Is this normal? And, how long should it attempt to light before it actually does? Gas works just fine in stove/heater... so that is not the problem. Thanks!