Startup (inrush) of 2.7 cu ft refrigerator?

pigman1 wrote:
Good post, GDETRAILER. I couldn't agree more. As a practical example, we're currently using a dedicated 1250W TrippLite inverter to run the Kitchen Aid household refrigerator, a 16.5 cu ft chest freezer and a 3.5 cu ft basement freezer. We have a monitor on the TrippLite and have not once been into the surge overload on the inverter. The TrippLite has a 150% surge ability for up to 60 minutes and a 200% surge capacity for 10 seconds.

X2 on the Triplite surge capacity. You just will not get this kind of surge capacity out of any other brand including most PSW inverters.

Good post, GDETRAILER. I couldn't agree more. As a practical example, we're currently using a dedicated 1250W TrippLite inverter to run the Kitchen Aid household refrigerator, a 16.5 cu ft chest freezer and a 3.5 cu ft basement freezer. We have a monitor on the TrippLite and have not once been into the surge overload on the inverter. The TrippLite has a 150% surge ability for up to 60 minutes and a 200% surge capacity for 10 seconds.

landyacht318 wrote:
In my opinion the residential fridges for those without access to grid power is a false economy.

One saves money on the fridge, but then most need to upgrade the inverter, the battery bank and the charging system to deal with the inefficient fridge that one also needs to fabricate a door lock for, and one whose vibration resistance in a moving vehicle is unknown.

The 12 volt compressor fridges are not so expensive in the long run.

I just couldn't imagine having to run an inverter 24/7 to power the fridge. I'd rather go back to ice and a cooler.

:R

Spoken like a fire dragon hugger.

False economy?

No.

Simply stated buying a $1800 RV fridge or attempting to rehab an old RV fridge even for $600 is "false economy".

Buying a new RV fridge is no guarantee that it WON'T fail in a few years and putting $600 into a rebuilt cooling unit is just a total waste of time since it only addresses ONE part that fails on a RV fridge. Then you have a USED control board, gas valve and even electric heater to go bad.

I am NOT afraid to boondock with my home fridge conversion, simply put just one pair of 6V GC batts gives me PLENTY of battery for 24hrs before needing to run a gen.

Cost, 10cu ft fridge $300, I wanted an inverter anyways so I chose a Tripplite PV1250 to handle fridge and anything else I wanted to power from battery. The inverter was $260 but since I was planning to install one I don't consider it in the cost of conversion.

That inverter by the way solves another issue, it has a setting which allows it to sense if there is an AC load and it turns on off with the AC load. Fridge T-stat calls for cooling and the inverter powers up, when T-stat reaches correct temp it turns off and the inverter turns off. Saves a chunk of battery power.

Needed new battery as when I bought the trailer there was none with it, a pair of 6V GC batts from Sam's club for $140 took care of that issue.

I already have portable gen so no cost there.

So IF you want to add up my costs I have a whole whopping $700 into a fridge conversion which works MANY times better than ANY RV fridge. But for me the cost was only $300 for a new fridge instead of putting $1800 into a trailer that was only worth $1000 to start with.

No more fighting 55 degree temps during 100 degree outdoor temps then at 70 degree temps at night wake up in the morning with fridge temps below 32 and completely frozen solid milk. Not to mention wondering if the food we at was actually safe to eat or not..

To get back to the OPs question, fridge compressors typically have 1.1A-1.2A RUN current, typically you will see a surge current of 8x to 10x the run current. Mine was marked as 1.1A at 120V, actual run current I measured was .9A at 120V, the startup surge on mine measured about 9A at 120V.

This works out to a surge of 1080W at 120V, I selected a inverter that is rated 1250W CONTINUOUS to AVOID not having enough inverter capacity to RELIABLY start the compressor.

With that said, some folks have been able to get away with using a 800W inverter which has a surge rating of 1600W but I think that is pressing it a bit. Select a min of 1000W with 2000W surge and keep the 12V wiring as short as possible along with some very heavy ga 12V wires (I used 1/0 at 3ft away from the batteries).

Inrush rule of thumb used to be 3-5 times the running current.

In my opinion the residential fridges for those without access to grid power is a false economy.

One saves money on the fridge, but then most need to upgrade the inverter, the battery bank and the charging system to deal with the inefficient fridge that one also needs to fabricate a door lock for, and one whose vibration resistance in a moving vehicle is unknown.

The 12 volt compressor fridges are not so expensive in the long run.

I just couldn't imagine having to run an inverter 24/7 to power the fridge. I'd rather go back to ice and a cooler.

popeyemth wrote:
Compressors. At least that's my reading.
No "inrush" on absorption they stay pretty constant .

Went through this a few years back when selecting an inverter for someone and came up with 6 plus or minus. (using an analogue meter)

Compressors. At least that's my reading.
No "inrush" on absorption they stay pretty constant .

Are we talking RV absorption refers or Compressor refers????????? Doug

No "locked rotor " specs on my data plate and I can run a fan AND my fridge on my Harbor Freight 700 Watt inverter-no problem
On further thought my inverter does have a 1500 watt surge capacity.
I find my Kill A Watt to be plenty close enough for my guesstimating :)

Pigman is right on the measuring, it takes a data recording meter or scope to nail the startup current. FWIW, my 1.7 dorm fridge drew too much from locked rotor to be driven by a Samlex 600w inverter. I replaced the Samlex with a Xantrex 1000W inverter and all is good, now. An estimate of the current at startup of the 1.7 could be 4-5 amps with an instantaneous peak of greater than 5 amps.