if you have a trip under 3 hours, the fridge can stay cold for that amount of time.
we just took a 2 1/2 hour drive to camp. we had left the fridge hooked up to electric overnite before we took off.
it stayed cool till we got to the campground, without running it on propane.
but we have run it on propane, enroute, on longer trips and have no problems with doing it.
and Zoe the Wonder Dog(R.I.P.)
'07 Roo 23SS pushing an '07 Chevy Avalanche
Equalizer WDH and Prodigy BC