Help with a solar project.

[DFBrews]

When you have power (daytime), run the compressor past its usual cutoff point, which is usually around 0F. R134a boils at -15F, so maybe somewhere around there. The extra 15 degrees is a thermal buffer that acts like a battery. Maybe enough to make the system run battery-less. If you keep the freezer mostly full (water/ice bottles?), your opening losses will be minimal and you'll have crazy good heat capacity.

My chest freezer cuts out at -10 I did a PID controller to bypass the factory thermostat and program it to avoid short cycling. I run my lagering chamber for home brewing this way I have a tub of glycol a pump and then a heat exhxanger in a separate box where i keep the beer

[Not_A_Llama]

My chest freezer cuts out at -10 I did a PID controller to bypass the factory thermostat and program it to avoid short cycling. I run my lagering chamber for home brewing this way I have a tub of glycol a pump and then a heat exhxanger in a separate box where i keep the beer

Cool, let's rejigger my calculations, then..
1.94 kJ/kgK * 15 cubic feet * (1 g/cm^3) * 70% * 5 kelvin = 0.8 kWh

So it's less rosy here. A lot depends now on real-life performance - can your freezer keep a load of -10F goods below 0F in a 24 hour span? If so, you're probably good battery-less. If not, you're still discounting your battery installation.

Assuming your 6V figure from before, that's 800 Watt*hours / 6 volts = 133 Amp Hours of battery. Half and a bit of battery.

Edit: Mother of god. I have created the ultimate unit mixing disaster. Begone, google calculator! Look on my works, ye mighty, and despair!

[th3w01f]

I'm still a bit confused.... and I have to admit I haven't' done anything to sober up, but are we talking about the equivalent of 'overclocking' freezers.? So I bought my freezer at Best Buy and it only goes down to 0f but if i make some chages i can get it down to -30 during periouds of cheap electiricitly? That would be awesome but I'm not sure I bought the right one.

Really I just want to keep a freezer running while charging some basic household devices during a major outage.

[Not_A_Llama]

Yeah, basically. Except that with the common variety of refrigerant on the market, DFBrews reports the most he can get down to is -10F. My spitballed earlier number was -15F, based on the boiling point of R134a.

[DFBrews]

I might be able to go lower. but my glycol mix is only a -20 and want to keep some fluidity so the pump doesn't work too hard. I just checked my other chest freezer where I keep my bulk meat and it is at -5 with no modifications

[th3w01f]

Does anyone have a recommendation on where to find batteries in Denver, or preferable south Denver - Co Springs?

I'm going with 8 x 6v. I've read decent things about the ones from Sams and Costco. Our local Sams only has the more expensive ones for $117 + core charge. At that price, I think going with Trojan T105 would be better for just a little bit more.

I'm going to check Costco today, I've seen recent posts from other stats with Sams and Costco having the lower end 6v (~210ah) for under $90.

[Not_A_Llama]

Says these are in stock at the Castle Rock Club (#4853) 5940 Promenade Pkwy.

https://www.samsclub.com/sams/durace...to:product:1:1

[th3w01f]

Says these are in stock at the Castle Rock Club (#4853) 5940 Promenade Pkwy.

https://www.samsclub.com/sams/durace...to:product:1:1

Thanks, I looked when I was there but didn't see those and there was no one to help. I'll go back today and take a closer look.