How many batteries do I need to run this fridge for several days?
Truck Fridge Built-In 12-Volt DC Refrigerator With Freezer CRX-50 By Dometic
I asked a similar question, but I am asking again with more detail on my end. I want to instal an AC/DC fridge in a trailer. When the trailer is working it's plugged into shore power, but when it's off (over night, or weekend) its unplugged so I want to set up a battery bank to keep the fridge running during this time. One answer I got was that the fridge draws 40W. To calculate amp draw you multiply watts and volts, thats 480 amps. That many amps would require a massive bank of batteries to operate. In the item description is says 12-Volt only draws 6 amps. 6 amps at 72 hours is about 580 amp hours for a battery load so that's like 4 batteries depending on size. Maybe my math is off, I dont know. What I am asking is how to calculate the amount of amp hours needed to run this fridge for 72 hours. I may be looking at the wrong fridge, or maybe my needs are too big and nothing exists that will work. I'm in the south so cold temps are not an issue. Heat is though. I know that is a factor as well.
Open Oct 12, 2017 - 05:47 AM
Voted Best Answer
Oct 12, 2017 - 06:18 AM
The fridge will definitely not draw 480 amps. Even a central AC on 240 volts does not draw more than 30 amps. I believe its going to be dividing 40 watts / 12 volts. That is 3.33 amps and it may draw up to 6 amps during the start up of the compressor motor. The fridge will run maybe half the day or even less on its cooling cycle so lets just say it is a full 6 amps and 6 amps x 12 hours = 72 amp hours a day and that would be a conservative estimate. The rest of the math will depend on your storage capacity in your batteries. Hope this helps!