Need help preparing for winter

[Thos]

I am very glad to know that my LiFePO4 batteries won't be getting damaged due to the low temp disconnect to prevent charging in a freezing environment. But does that mean that I must definitely and absolutely avoid discharging them in a freezing environment as well or is it OK to do that?
Also, I would love to have some suggestions as to what kind of material would be the best to use for insulating the battery box.

 

[FilterGuy]

Also, I would love to have some suggestions as to what kind of material would be the best to use for insulating the battery box.

I used 2" foam board insulation from Home Depot. I made sure all seems overlapped and "glued" with calking to make sure it is sealed.

@curiouscarbon recently pointed out some vacuum sealed insulation panels from Panasonic in this post:

On Keeping LFP Warm

Did you get a chance to look at/test the powermon? I'm looking to buy a few more Low Voltage Disconnects. I need one for my 12VDC dehumidfier, and another for my battery heater. I can hold off for a few more months before ordering. Was it easy to program? Capable of very close voltages...

diysolarforum.com

They are very expensive but you can get a huge R value in a very thin wall.

But does that mean that I must definitely and absolutely avoid discharging them in a freezing environment as well or is it OK to do that?

I have always heard you can discharge below 0C..... but I think it starts getting questionable at about -20C.

 

[Thos]

Big Thank-you to Filter Guy for the interesting options and bottom temperature fact about discharging LiFePO4's in a Canadian winter.

 

[curiouscarbon]

But does that mean that I must definitely and absolutely avoid discharging them in a freezing environment as well or is it OK to do that?

Here is a resource to address your concerns about temperature and discharging and charging: https://diysolarforum.com/resources/general-lifepo4-degradation-vs-temperature.172/

Basically, discharge at 0 deg C ok. Discharge at -20 deg C will be lower due to higher resistance i think but it’s also good to keep the temp up close to 25 deg C

Also, I would love to have some suggestions as to what kind of material would be the best to use for insulating the battery box.

Normal foam insulation work! ?

There’s also fancy vacuum insulated fiberglass panels that can make it take up less space if space is at a big premium. Panasonic makes “U-Vacua” series and I’m testing them for various stuff.



Here’s my franken-mini fridge that is being outfitted with vacuum insulated panels to evaluate how it affects the power usage of the device.

Neoprene (adhesive backed best) and hot melt glue work great with it.

It’s obviously a fridge but same concept of insulation ?

Hope this helps,

Good luck!

 

[Tecnodave]

@curiouscarbon ,

Does your mini fridge have a hot spot on one side, mine does and calling the seller confirmed that is where the coils are that dump the heat. My Grape Solar DC fridge gets quite warm low on the right side , rigged up a dc fan with a sensor on the main fan inside the unit to turn on the added fan, small magnets glued to fan body and just placed on hottest spot reduced compressor run time about 12-15% . fan is 6” about 2 watts , turn on sensor is speed detector chip (tach) please post your insulation results..

 

[curiouscarbon]

Does your mini fridge have a hot spot on one side, mine does and calling the seller confirmed that is where the coils are that dump the heat.

On this midea unit, both left and right exterior walls have condenser embedded, confirmed with hand and seek thermal camera.

Still considering the fan to exterior wall approach and might try yet. For now, installed thermal pad across hot condenser area, followed by thin copper sheet, and aluminum water block. Still finalizing stuff..



OP pls forgive my fridge-threadjacking?

Insulation ya!

What I can say is the vacuum panels feel much warmer than the rest of the original fridge walls. So subjectively it seems to be doing ok so far at separating hot and cold.