A 7 gallon tank, AKA a 30# LP tank. If full, it will run a RV fridge a really long time. It should be in weeks to maybe even months if that is all that is on.
The RV fridge does need 12 VDC to run on LP unless you have a really old gas pilot one. 12 volts runs the control board, gas valve and the igniter . The battery will go dead if not on shore power or recharged before the 30# tank will ever run out.
How many hours are you trying to run it and in what outside heat/temperature?
If you really need to to be close on the usage, will need the model, make an year of the fridge to find out the BTU rating and back into how many BTU's are in the LP tank and at what outside temp.
Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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