Can lifepo4 100AH battery power chest freezer for how long?

[joeExotic]

I have a small chest freezer. It uses 4 amps and goes on and off every 30 minutes. If I buy a LiFePO4100AH battery will that be enough to keep it on at night? I am in Los Angeles so it's mostly always sunny all year round. I would also use a 10amp PWM charge controller that can power LFP battery.

So basically is 100 AH LiFePO4 battery enough for only 4 amp chest freezer.

 

[rmaddy]

Assuming you mean it uses 4A at 120V then that is 480W. 480W for 24 hours is 11520Wh. But the freezer is probably only on about 33% of the time so you really use 3840Wh/day.

A 12V 100Ah LiFePO₄ battery is 1280Wh. So the battery would be 100% depleted in a little less than 8 hours.

You should get a kill-a-watt type meter and get an actual reading on how many watt hours your freezer uses per day over a several day period. Then you can better determine how much battery and solar you really need.

 

[Bluedog225]

Volts X amps = watts.

Watts are watts.

 

[Bud Martin]

I have a small chest freezer. It uses 4 amps and goes on and off every 30 minutes. If I buy a LiFePO4100AH battery will that be enough to keep it on at night? I am in Los Angeles so it's mostly always sunny all year round. I would also use a 10amp PWM charge controller that can power LFP battery.

So basically is 100 AH LiFePO4 battery enough for only 4 amp chest freezer.

You need to clarify if you are talking about 4A 120VAC or 4A 12VDC (or what ever Voltage it runs on), if it is AC then that is a lot of power for small chest freezer, and if you use inverter then you have to factor in inverter loss also.

 

[joeExotic]

It's 4amps 120VAC from the wall

 

[Bud Martin]

It's 4amps 120VAC from the wall

Man, that is a lot of power for small freezer, my 1996 side-by-side 25cu ft draws less than 2A while compressor is running, and about 6A when the defrost heater comes on for about 20 minutes.
Get Kill-A-Watt and run it for a couple days to collect the data.

 

[joeExotic]

do these pics help?

 

[rmaddy]

It says 250kWh/year on average. So that's 250,000Wh/year / 365days/year = 685Wh/day. That's substantially lower than the estimate I made earlier based on 4A and 33% duty cycle.

So a 12V 100Ah LiFePO₄ battery (1280Wh) can run that for roughly 45 hours. But that assumes the inverter is 100% efficient and you use 100% of the battery. Neither is true. So more like 33 hours in real life.

However, as myself and others have said, get a kill-a-watt meter and get real measurements from your actual usage of the freezer.

 

[Bud Martin]

Startup current is not the same as running current. I measured almost 30A of startup current on my fridge.
Did you measure the current draw once that the compressor start running. The printed power consumption does not match your 4A of running current at all.

 

[E. Cho]

Not an apples to apples example but ...

I run 2 chest freezers off of a 24 volt 100 AH battery and my 20 year old low frequency 4,000 watt inverter 24/7. The battery is recharged quickly with about 1200-2000 watts of solar depending on time of day, cloud cover, sun angle, time of year.

The battery and inverter and large gauge 4/0 wire have zero problems starting and running these freezers, plus TV, laptop, lights, other devices during the day and into the evening. By morning, the battery may lose 15-20% but not just from the freezers.

One freezer uses 3.2 amps at 24+ volts to run and they cycle several times per hour. One 7.2 cu ft chest freezer is used as my fridge, the other 3.8 cu ft version is my freezer. They both use the same number of amps / watts. Both freezers are in my kitchen at 68-72 degrees F, year round.

Using these and ditching the toxic propane fridge and it's 1.2 cu ft freezer was a fantastic move and much less expensive.

My Kilowatt meter registered energy use of the larger chest freezer at fridge temperature at 4.8 KWh over 63 hours and 53 minutes at 120 volts inverted from the 24 volt 100 AHr LiFePO4 battery. (I kept forgetting to check after an hour or 24 hours for even #'s.)

 

[Leeds]

A 100AH 12v lithium battery is ample to run a freezer as a fridge for 24 hours as long as you don't leave the AC on when it's not needed.
But your power needs to run it as an actual freezer are much greater. You'd certainly be on the hairy edge at best.

An energy audit of your freezer running for a few days will tell the whole story.