Scotty needs battery power

[Rose4aname]

I have a little Scotty and have always just plugged in to an outlet when camping but we have recently found several campgrounds without power that we want to go to. What kind of battery set up would you suggest? My husband does all the electrical work and is leaning towards a marine battery, I just wondered what kind is best. I would like to run the fridge but just lights work for me too. Any ideas?

[bobhenry]

I am about to run a larger dorm sized fridge off grid 24/7 so I was very interested in this question.





I found this on the net......


Inverter Ratings

The manufacturer’s label on most inverters gives two capacity values. The “continuous wattage” is the AC power output the inverter can supply 24/7 for as long as the DC input lasts. The “peak surge wattage” is the AC power output the inverter can supply for a split second. A typical inverter offered at discount stores or home centers provides 1,500 watts continuous AC power and 3,000 watts of surge power. This unit should run a typical 16 cu. ft. refrigerator with no problem.


Battery Capacity

You also need to know how much DC battery capacity you’ll have to have on hand to run your refrigerator. To determine your battery requirement, first convert your refrigerator’s AC running watts to DC amps. The starting wattage doesn’t last long enough to count. To find DC amps, divide AC running watts by 12 and multiply the result by 1.1. A fridge needing 600 AC running watts will draw 55 DC amps.

My little dorm fridge shows 1.2 amp draw so 1.2 x 120 = 144 running watts this 144 / 12 = 12 x 1.1 = 13.2 dc amps


Battery Ratings

Lead-acid rechargeable batteries are rated in ampere-hours. A typical battery rated at 105 ampere hours can deliver 105 DC amps for one hour before it runs out of power. In general, you risk damage if a rechargeable lead-acid battery is drained below 50 percent of capacity, so you safely can draw 105 amps for only 30 minutes. A fridge drawing only 55 DC amps can be run for about 60 minutes of continuous duty off a 105 ampere-hour battery. Refrigerators run intermittently, not continuously, so you need to determine how many minutes out of each hour your refrigerator actually runs. If your refrigerator draws 55 DC amps for 20 minutes out of each hour, you will need to recharge your battery after three hours of refrigerator operation. A second battery will keep your fridge running while you recharge the first battery.

I am pairing two 6 volt deep cycle batteries (320 AH) so if 1/2 is available that's 160 AH this 160 / 13.2 dc amps is just over 12 continuous hours. If your little fridge runs 10 minutes out of an hour you should be able to go 72 hours before a charge is needed with this type of a setup. Mine will be connected with a solar charging system so I feel I am set for a cloudy day here and there.

[Rose4aname]

Thank you, your fridge looks just like a freezer I have (not in the camper). My fridge is also a tall Dorm Fridge. I will pass this on to my Hubby and see what he thinks. We were not thinking of solar but using a charger of some sort. Not real sure what kind yet. He told me that he saw prices that were outrageous to decent and wasn't sure what we really needed or what we could get away with. I am confident he can hook everything up, just wondering what the best purchase would be.