westend wrote:
For reference: I run a small dorm fridge with a 300AH bank and a Xantrex 1000W inverter. It draws 80 w at a 1/4 duty cycle in summer ambient temps. A larger residential fridge will use a bit more power but not much. The locked rotor draw is the reason to use a 1000W+ inverter and the Tripplite should overcome that easily. 4 to 5 hrs, of run time should be easily accomplished with two 12V batteries and the charging of the vehicle.
BTW, you won't miss solar until you have some.:B
Actually interestingly enough the compressor current draw of a 1.2 cu ft dorm fridge is nearly identical to my 10 cu ft apartment size fridge I used. Pretty much all fridges use the same compressor which draws 1A-1.2A run current.
What I have observed however is the small "dorm" fridges have LESS insulation than the larger apartment size fridges.
I compared a 1.2 cu ft fridge I have in my basement and my apartment fridge when I was initially testing my conversion setup..
The smaller dorm fridge was drawing 90W and the apartment fridge was also drawing 90W. Basically a dead heat..
BUT, the dorm fridge compressor would run for 20 minutes then shut off for TEN minutes so it had a duty cycle of 40 minutes ON and 20 minutes OFF for every hr.
The apartment fridge ran 20 minutes and was OFF 40 minutes.
Both were operated side by side in the same temperature conditions.
If you closely look at a dorm fridge you will notice that is has about 3/4" of insulation.
The apartment fridge I have looks to have at least 2 inches of insulation.. Makes a huge difference.
Couple that with my Tripplite inverter with the load sense and now you no longer have to account for wasted power due to the inverter idling while the compressor isn't running!
There have been folk who have been able to get a home fridge to run from 800W inverters but I do think that they are pressing things a bit.
A 1000W Tripplite should have plenty of surge capacity to reliably start the fridge. However you MUST use HEAVY ga wire on the 12V side AND keep it short. Otherwise the wire will drop too much of the 12V and the inverter will be close to low voltage shut off during the start up surge.
