Great inverter setup to run residential fridge in your RV!
When I bought my RV it had a failed fridge. After a $180 Dinosaur board didn't fix it, the $800 cost for a new cooling unit or possibly $2500 to get a similar sized new unit were not appealing. I looked around and the cost of a residential replacement was $580. I decided that the way to go was a residential fridge and when the need arose, add an inverter to run off 12V. I bought the fridge a couple years ago and have only recently run into a couple situations where I finally needed the inverter capability. That is the reason for this post.
I looked long and hard and came across this MicroSolar 1000W (2000W peak) Pure Sine inverter for $169 on Amazon. It does come with the two short wires and the remote control box.
Microsolar Pure Sine Inverter from Amazon
To operate the circuit, I bought a 30 amp, 120V DPDT contactor off Amazon(NTE model R04-11A30-120) and put it in a plastic box.
I then made some pigtails from 14ga extension cord so that the coach 110V power, inverter power and fridge connection cord can all hookup correctly. The terminal at the far right goes to the fridge. The posts on the far left go to the inverter 120V. The remaining two terminals connect to the coach 120V.
The last thing to think about was the surge power needed to run the fridge. The 4ga wire from the old fridge isn't really up to snuff for the surge amperage to start the fridge, but is plenty to run off of. My solution was to get a 30Ah battery, put it inside the coach and then hook the short leads that came with the inverter to the new battery. The new battery is also connected to the original 12V +/- that operated the original fridge and there is a 100A fuse that disconnects the new battery from the + lead.
So in operation it works as follows.
When I don't have 120V in the coach plugs, the contactor is in its de-energized state. The inverter can be turned on and it sends 120V to the fridge. When the fridge turns on, the closest (small battery) can take the brunt of the power surge and then things run happily.
When there is 120V in the coach plugs (from shore power or genny), the contactor energizes and sends coach power to the fridge instead. Since the inverter doesn't have a 120V load, it pulls almost no power from the 12V and the small battery gets charged by the coach 12V system, along with the main coach battery.
I tested the whole setup this weekend and it worked great. I was able to run about 12 hours before the coach and small battery were drained so much that they went below 12V and couldn't start the generator. I started the RV engine and fired up the generator to re-charge the batteries.
Now that I know how much run time I get on the existing batteries, I realize that I need to add another BIG coach battery or two somewhere, so that I don't drain anything down totally and risk killing cells. I am quite sure I can add a sealed box underneath and connect it all in. If I really start doing a lot of longer term dry camping, adding solar charging will be the next step.
For now, I am very please to have found an affordable inverter option.
Jose
I looked long and hard and came across this MicroSolar 1000W (2000W peak) Pure Sine inverter for $169 on Amazon. It does come with the two short wires and the remote control box.
Microsolar Pure Sine Inverter from Amazon
To operate the circuit, I bought a 30 amp, 120V DPDT contactor off Amazon(NTE model R04-11A30-120) and put it in a plastic box.
I then made some pigtails from 14ga extension cord so that the coach 110V power, inverter power and fridge connection cord can all hookup correctly. The terminal at the far right goes to the fridge. The posts on the far left go to the inverter 120V. The remaining two terminals connect to the coach 120V.
The last thing to think about was the surge power needed to run the fridge. The 4ga wire from the old fridge isn't really up to snuff for the surge amperage to start the fridge, but is plenty to run off of. My solution was to get a 30Ah battery, put it inside the coach and then hook the short leads that came with the inverter to the new battery. The new battery is also connected to the original 12V +/- that operated the original fridge and there is a 100A fuse that disconnects the new battery from the + lead.
So in operation it works as follows.
When I don't have 120V in the coach plugs, the contactor is in its de-energized state. The inverter can be turned on and it sends 120V to the fridge. When the fridge turns on, the closest (small battery) can take the brunt of the power surge and then things run happily.
When there is 120V in the coach plugs (from shore power or genny), the contactor energizes and sends coach power to the fridge instead. Since the inverter doesn't have a 120V load, it pulls almost no power from the 12V and the small battery gets charged by the coach 12V system, along with the main coach battery.
I tested the whole setup this weekend and it worked great. I was able to run about 12 hours before the coach and small battery were drained so much that they went below 12V and couldn't start the generator. I started the RV engine and fired up the generator to re-charge the batteries.
Now that I know how much run time I get on the existing batteries, I realize that I need to add another BIG coach battery or two somewhere, so that I don't drain anything down totally and risk killing cells. I am quite sure I can add a sealed box underneath and connect it all in. If I really start doing a lot of longer term dry camping, adding solar charging will be the next step.
For now, I am very please to have found an affordable inverter option.
Jose
