Inverter to run outside fridge

The fridge wont be running all the time, so yes it's doable. But your power number seems low.
Get one of these Kill a watt or something similar and actually measure what the amps/watts are on start up so you don't buy too small an inverter, or use too light of wire.

mhsmith wrote:
120 volt fridge. Rated at 1.1 amps which gives me 132 watts. I am looking at possibly a 180w to 200w inverter.

I think you will be disappointed. I would guess 600 minimum and #6 wire.
Hard to know surge requirements with motors. These small fridges are notorious for large start requirements. The full length of wire to the battery will work against you to provide the required volts and amps the inverter needs.

That kill-a-watt will not measure surge current.

wanderingaimlessly wrote:
The fridge wont be running all the time, so yes it's doable. But your power number seems low.
Get one of these Kill a watt or something similar and actually measure what the amps/watts are on start up so you don't buy too small an inverter.

To be clear, OP was wanting to use existing wiring to the fuse panel and or 10 ga wire.

None of that wiring will be able to support the startup surge of a highly inductive load from the fridge compressor.

As long as the OP uses a heavier wire and not the existing wire and they mount the inverter as close as possible to the batteries of course "it can work".

I am speaking from experience as I studied and worked through this problem for quite some time before I committed money to parts.

I HAVE measured my fridge running current AND the startup surges, while a small inverter on paper would look like it "should" work, it will not because of the surge current.

Others on this forum who faced this issue had also tried many small inverters from 300W to 500W.. Those small inverters all had issues with startup surge, general consensus has been around 700W inverters tend to have better results.. and the larger the inverter above 700W the better results you will get. That is why I recommend 1000W inverters for this job even though most of the time the fridge will be using less than 1/10th of the capacity of the inverter.

The difference in cost between a 500W inverter and a 1000W inverter are not all that great. Your talking often only about $60-$100 more for a 1000W inverter over a 500W inverter.

Fridge compressors are a very complex current device unlike say an incandescent light bulb. Incadescent lights pose nearly no surge current so you can run an inverter right near the max rating, fridge compressors however, not so much.

Split phase motors frequently demand 500% of run current to start. If you design your inverter circuit for 500 watts you will lessen the certainty of failure.

I thank everyone as this is the kind of info I need to determine if I can do it or suck it up and leave it. Gonna need to do some testing at this point and once again...thanks.

Another possibility to handle the surge with smaller wire is to up your inverter input voltage to 24 or more, but, that's not something most people even consider.

You have a truck towing a trailer. It is just to keep the drinks and some food cold while driving till you can get 120v for the fridge.

You can try the inverter route with some difficulty as others have posted.

Another way is just have a "cooler" that could hold about as much as the outside fridge in the trailer does. Cooler powered from the truck's 12v system. A DC-DC converter might be useful in that role, but maybe not necessary. Cooler could be inside the cab or in the box.

"Cooler" could even be another small 120v fridge in the back of the truck box with inverter, where the inverter is powered by the trailer batts on the tongue via fat- wire jumper cables.

Might even be able to use the same fridge by just carrying it back and forth between the truck and the trailer if it is not installed in the trailer in an awkward way.

Cooler could also be a set of ice packs in the outdoor fridge and let it be without power.
Put the icepacks in the freezer inside overnight to be ready the next day.

time2roll wrote:
Cooler could also be a set of ice packs in the outdoor fridge and let it be without power.
Put the icepacks in the freezer inside overnight to be ready the next day.

Have done this on shorter trips(2-2/12hrs)

BFL13 wrote:
You have a truck towing a trailer. It is just to keep the drinks and some food cold while driving till you can get 120v for the fridge.

You can try the inverter route with some difficulty as others have posted.

Another way is just have a "cooler" that could hold about as much as the outside fridge in the trailer does. Cooler powered from the truck's 12v system. A DC-DC converter might be useful in that role, but maybe not necessary. Cooler could be inside the cab or in the box.

"Cooler" could even be another small 120v fridge in the back of the truck box with inverter, where the inverter is powered by the trailer batts on the tongue via fat- wire jumper cables.

Might even be able to use the same fridge by just carrying it back and forth between the truck and the trailer if it is not installed in the trailer in an awkward way.

This may end up bein they to go. Just didn't want to add more weight than necessary but it is the simplest way to do it.