Re: Off griding my cooler
Welcome to the forum. Glad to see you got the posting thing to work.
How did you come up with those current numbers? Usually you can not detect the surge current of a motor.
I would not go in for trying to modify the cooler. Probably more trouble than it's worth.
To take it off grid you will need to have batteries. Not many things can be directly powered by solar panels. Those that do will function only when the panels put out power. That's not a good choice for a cooler.
As for sizing the batteries you have a matter of comparing Watts on the AC side to Watts on the DC side. If the cooler draws 6 Amps @ 120 VAC is 720 Watts, but when converted to DC you will have conversion inefficiency and also the inverter's consumption to deal with. So the 720 Watts becomes 800 Watts and the inverter will consume a further 20 Watts (you will not be able to run this device off a small, low-power inverter as its running power is high and its motors will have a significant surge demand). Thus on the DC side you need to supply 820 Watts.
Now comes the time factor. How long does the cooler run consuming this power? Will the inverter be on all the time? This much load operating all the time is a huge amount of Watt hours: 820 * 24 = 19,680 Watt hours per day. This is why it's a good idea to use a Kill-A-Watt and see how many Watt hours it typically uses in a day. It probably is not nearly 20kW hours.
Once that number is determined you can pick the best system Voltage and battery bank size.
How are we doing so far?
Four 175 Watt panels, OB MX60, 232 Amp hrs, OB 3524, Honda eu2000.
Ohm's Law: Amps = Volts / Ohms
Power Formula: Watts = Volts * Amps