Cold weather options for LifePO4 batteries

[phemens]

This thread wasn't started to debate the merits of LifePO4 vs other technologies. For various reasons I elected to go with it, very happy with performance thus far. One variable that has suddenly become more of a potential issue is cold weather charging. We purchased a plot of land up north and are camping there, and we've seen already some nights down below 0C. We are completely off grid, with solar and generator (only when needed) as power sources. For the couple of mornings where we had frost, I ran a space heater in the front compartment to get the batteries up to a temperature where I felt it was safe to charge (the solar comes on progressively through the morning, starting with a few amps and then ramping up to 80-90A by mid-morning). With the battery capacity I have (600AH, probably 500 usable), using the space heater isn't a problem, but it's not very efficient, and it's not a solution for when we're not there (we go up for long weekends right now).
I will be adding more insulation to the compartment (already have some R12 styrofoam sheeting, but will make a box for the batteries). I also ordered a small 12V PTC fan heater that will draw maybe 12A that I ordered online that I would install in the compartment to run full time (or maybe on a temperature control?).
Looking for other suggestions, I've seen recommendations for use of small 7.5 watt elbow pipe heating mats. What are you using if you are in the same situation?
Thanks in advance.

[phemens]

Itinerant1 wrote:

phemens wrote:
The guy that built my batteries is noodling around with these Link
They're heating pads for pipe elbows, they draw 7.5 watts each, he says I'd need 2x battery, which means 12 total or 90 watts total (6 batteries). He's hooking them up to a 1207 temperature controller. That's what I'm going to try and the controller for the blown air, maybe the pads are a better long term solution. I guess another option would be to stick the larger tank heating pad to a sheet of aluminum to span the footprint of all the batteries.
We'll see!

I entertained this Facon warming padunder the batteries. I would of stuck it to an aluminum sheet cut to fit the wooden structure containing the batteries to spread the heat as best as possible. Wired into the 12v fuse panel but having a toggle switch to give power when needed. The only issue I was worried about is it being sandwiched between the 1/2" rubber pad and the aluminum sheet, then having the batteries sitting on top. I don't know if it would matter?

At 5.6a while running is so little of a draw, which is equal to the humidifier that is always running in the trailer.

I wouldn't stick any of the heating pads directly on batteries incase it quit working so not to have a sticky mess on them.

That's what I was looking at initially, sticking it to an aluminum sheet underneath the batteries but on top of styrofoam insulation. Given the relatively light weight of the LifePO4 batteries I would think the weight on the heating pads would be ok.
I would wire it into a temperature controller then an on/off switch. That will be the permanent solution I think. 5.6 amps is more than fine as long as it can maintain the temperature at about 5C.
I may be building a new set of 280AH battery banks next spring, and one possibility would be to insert the heating elements in between the cells before they are put together.

[Itinerant1]

phemens wrote:
The guy that built my batteries is noodling around with these Link
They're heating pads for pipe elbows, they draw 7.5 watts each, he says I'd need 2x battery, which means 12 total or 90 watts total (6 batteries). He's hooking them up to a 1207 temperature controller. That's what I'm going to try and the controller for the blown air, maybe the pads are a better long term solution. I guess another option would be to stick the larger tank heating pad to a sheet of aluminum to span the footprint of all the batteries.
We'll see!

I entertained this Facon warming padunder the batteries. I would of stuck it to an aluminum sheet cut to fit the wooden structure containing the batteries to spread the heat as best as possible. Wired into the 12v fuse panel but having a toggle switch to give power when needed. The only issue I was worried about is it being sandwiched between the 1/2" rubber pad and the aluminum sheet, then having the batteries sitting on top. I don't know if it would matter?

At 5.6a while running is so little of a draw, which is equal to the humidifier that is always running in the trailer.

I wouldn't stick any of the heating pads directly on batteries incase it quit working so not to have a sticky mess on them.

[phemens]

folivier wrote:
Look on ebay for snowmobile hand grip warmers. I have a friend who added these to his Battle Born batteries. They are powered by the batteries themselves, he added an on/off switch, and a thermostat so they only turn on at the low temperatures he wants.

Interesting idea, thanks!

[folivier]

Look on ebay for snowmobile hand grip warmers. I have a friend who added these to his Battle Born batteries. They are powered by the batteries themselves, he added an on/off switch, and a thermostat so they only turn on at the low temperatures he wants.

[BFL13]

phemens wrote:

BFL13 wrote:
No idea, but since it is just to keep them from freezing, and not to get to room temperatures, maybe grab some ground heat? It is your land, so might be possible for a small-scale set-up? No idea!

https://en.wikipedia.org/wiki/Geothermal_heat_pump

It's an interesting idea and one we're considering for the eventual home we're going to build. We need to dig pretty deep here to get below the frost line, so the shallow dig type setups you see (with a length of pvc pipe down a couple of feet) probably wouldn't work very well here unfortunately.

If you are getting a deep well done anyway, maybe there is a way to piggy back the heat thing with the well? I don't have a clue, but might be worth a look.

https://www.puitsbernier.ca/en/arterian-wells/price-artesian-well/

[phemens]

BFL13 wrote:
No idea, but since it is just to keep them from freezing, and not to get to room temperatures, maybe grab some ground heat? It is your land, so might be possible for a small-scale set-up? No idea!

https://en.wikipedia.org/wiki/Geothermal_heat_pump

It's an interesting idea and one we're considering for the eventual home we're going to build. We need to dig pretty deep here to get below the frost line, so the shallow dig type setups you see (with a length of pvc pipe down a couple of feet) probably wouldn't work very well here unfortunately.

[phemens]

Second Chance wrote:
Battle Born sells thermostatically controlled 12VDC heating blankets for their LiFePO4 batteries. I installed them on my batteries for the upcoming winter. I think the specs say they come on at 35F and turn off at 45F. Installation was easy - "peel and stick" and then wire up the thermostat modules.

Rob

Saw those, they were over $200/blanket (?!)

[Second_Chance]

Battle Born sells thermostatically controlled 12VDC heating blankets for their LiFePO4 batteries. I installed them on my batteries for the upcoming winter. I think the specs say they come on at 35F and turn off at 45F. Installation was easy - "peel and stick" and then wire up the thermostat modules.

Rob

[BFL13]

No idea, but since it is just to keep them from freezing, and not to get to room temperatures, maybe grab some ground heat? It is your land, so might be possible for a small-scale set-up? No idea!

https://en.wikipedia.org/wiki/Geothermal_heat_pump

[phemens]

The guy that built my batteries is noodling around with these Link
They're heating pads for pipe elbows, they draw 7.5 watts each, he says I'd need 2x battery, which means 12 total or 90 watts total (6 batteries). He's hooking them up to a 1207 temperature controller. That's what I'm going to try and the controller for the blown air, maybe the pads are a better long term solution. I guess another option would be to stick the larger tank heating pad to a sheet of aluminum to span the footprint of all the batteries.
We'll see!

[phemens]

Itinerant1 wrote:
Depending on your heat duct maybe you can tap into it. Mine ended right above the batteries in the front compartment. I'll block the vent in the bedroom where this section is located so the air is forced down the pipe. There are 2 other vents in the bedroom/ bathroom so no lose in heat.

If we're running the furnace to heat the 5th wheel why not use some of it for the batteries.

Just to give you an idea. 😉

Good idea, but my bedroom ducting is further in, and I'd have a problem on the 4 of 7 days we're not there unfortunately.

[phemens]

2oldman wrote:
Aren't there battery blankets for cold temps? 80-90 amps of solar? Kudos.

Yep, at peak I see upwards of combined 90 amps off of 2 50 amp MPPTs...
The battery blankets I've found are 120VAC and would draw north of 50 amps @ 12v, too thirsty for my taste.

[3_tons]

Repurpose a RV tank heater pad...

3 tons

[time2roll]

+1 for a blanket or other contact heat source besides blowing air.
Stick on tank heaters come with a thermostat.
Possibly move them inside the heated living space.