"Non-Solar" Question: What's the best (UPS back-up style) battery to use with a refrigerator? (in preparation for a 3 week power-outage scenario..)

[shudog]

Hi, What's the best (UPS back-up style) battery to use with a refrigerator? (in preparation for a 3 week power-outage stype of scenario..)
(P.S. If anyone answers this, Please consider that If U answer me with anything technical, i will not understand what U R saying.. I'm new to this. I don't live off the grid YET. My only solar panels +batteries that i currently own are to power my street performace show, (+i havn't really used those yet either!) I just want to buy something like a UPS for a computer (to put between my frig and my wall.) -Preferably the smallest units that would work for a frig as i have multiple refrigerators in different locations, so i would actually need to buy several.. Thanks SO MUCH if anyone has knowledge on this topic to share !!!!!!!!!!! UPDATE: I was theorizing that i could to do this by (keeping the fig/freezers closed, and) using timers between the battery+frig to only give it juice in intervals (feeding the frig maybe 5-10% of the time?) to extend battery life for a lot more days in a total extended "power-is-out" emergency.. Has anyone ever tried this?

 

[Hedges]

3 weeks is too long for a reasonable battery backup. Modern fridge uses 1500 Wh/day. 3 weeks would be 30 kWh, which is a $5000 forklift battery weight several thousand pounds.

Solar panels to produce that power is about 400 to 500W (STC), about $150 to $200. In addition you need charge controller (and small battery plus inverter capable of starting fridge.

You may be able to use your car to recharge a battery (OK for smaller lead-acid, don't do with lithium unless you have an electronic charger to limit current draw to avoid killing alternator.

Portable generator $100 to $400 is more practical. Run until freezer cycles off, then stop.

With ice, freezer or fridge might last a couple days. Frozen water or brine in bottles will help, especially if not full. You can buy ice or dry ice to re-stock.

You can buy a propane powered fridge (used in RV) which should go for weeks on a 5 gallon propane tank. Same thing runs on electricity, but takes 5x as much electricity as a conventional fridge.

 

[shudog]

Wow THANKS, that was very informative.. sounds like my idea was delusional. (I'll try to edit my post) forgot to mention i was gonna use timers between the battery+frig (that i could turn on after the power went out) to extend the life of the battery by only giving the frig electricity in intervals (maybe 5% of the time?.. and then just keep the frig/freezer CLOSED as long as possible while i eat OTHER food instead. Would that help get me a week or 2 off of a smaller battery??
I'm recovering from toxic exposure (+a bit chemically sensitive), so the thought of running a power generator does not appeal to me.. (also don't own a car so I wouldnt be able to use it to re-charge a battery) but the SOLAR option sounds good, (only $150 to $200 for the solar panels to run 4 refrigerators??) Maybe i will make another post asking what are the best solar panels to put on a roof (on a windy Island that is prone to hurricanes) specifically for powering ordinary refrigerators.. (the time to learn about it, +buy it, get it shipped here, +to hook it all up. +maybe buy DC powered frig as well?? [someone told me to do that..?] This will all take time.) UNTIL THEN.. it would still be great if i could find a few batteries with timers as an insurance policy for all the food i have stocked up in my frig/freezers until i get my solar act together.. even if it only gives me 5-10 days with timers? (I'm a dreamer i know..) thanks again for all the info!

 

[Hedges]

We get PV panels cheap, either locally or from vendors like Santan solar. Shipping large panels (300W or so each) requires freight not UPS, so cost effective only for larger orders.) If you're on an island, have to see what shipping is effective. For wind, more mounting rails, and well secured to the roof (lag screws into joists, not just sheathing.)

$150 to $200 of panels might run one consumer refrigerator/freezer, not four. Charge controllers, inverters, batteries adds up to much more. Easier if they are all within reach of extension cords, so one system powers them.

Gas and diesel may bother you, but how about propane? you can get propane generators, exhaust should be pretty clean. (Well tuned cars are pretty clean too.) Propane refrigerators are available, should work fine for time without power. They can also be run on AC but due to power consumption they cost more to operate.

There are inverters which will produce AC from PV panels without batteries. Ideal is if you are allowed net metering, so your system offsets utility bill most of the time and also gives you backup power during grid failures. Some places like Hawaii have too much PV, upsets grid stability and they don't want more. One inverter is SMA Sunny Island with "Secure Power". If grid goes down, flip a switch and get up to 2000W AC if there's enough sun. Earlier and later in the day with less sun you get less power. But a 7000W grid-tie system would give you 2000W for several hours per day. Cost of inverter $2000 and panels $3000, mounting hardware and wiring $1500. That's a system that offsets about 100% of normal household consumption.

Something smaller may do all you need, which is why I think of a $500 propane generator. Solar makes sense if you use the equipment all the time, not just during power failures.

Four refrigerators ... how about canning, drying, salting ... our forefathers has the same issues but didn't have refrigerators.

 

[Delmar]

I just tested this with a APC SUA1000XL and external batteries. More details here. You will need to find a UPS capable of being connected to external batteries like the one in the link.

The internal 18AH battery pair would not start the fridge. Connected an external 35AH battery pair and the fridge started. The APC chart indicated the UPS can power a 100W load for 10 hours.

You will need to supplement the batteries with solar panels for three weeks operation.