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LiFePO4 heating pad for cold temperatures

The adhesive heating pads I'm using will conform to curves well. Sharp changes in depth, not so much. But not enough that I would be gooping up my batteries with paste. Should I ever decide to switch from 4s2p to 8s, I wouldn't want my cells permanently joined by epoxy. However, in theory, a 4s should mate right up to another 4s to make a correct 8s. The exception there is that if I have a cell go bad, removing it from the pack wouldn't be a lot of fun.
 
hour said:
FWIW I'm not finding it to be that big of a battery drain, though tonight will be a more proper test (low of 24*F and was below freezing at like 530pm)

For days in the 50's with some mediocre winter sun and lows around freezing, I've found my ammo can enclosure with < 1/4" thick foil-foam insulation to not dip below 50 averaged between bms and it's probe, until about 3am.

Then the floor heats til the average of the two sensors is 50*F again or the floor hits 105*F. It'll maintain 105*F in that case until the probes are back up to temp. It runs for just a few minutes at a time and only has run once or twice between 3am - 8am for the last nearly two weeks. And never dropped below set temperature. This is dialed in to only output around 30w, though the heat pad could run at over 120w.

First heat cycle is going to cut on soon tonight, it's 51*F average between two sensors.. the floor is 48*F. So once that 51 hits < 50.5, the process begins. I'm sitting with a full (188.8 of 190ah) battery so it'll be interesting to see what I wake up to with tonight being cold, and cold early.
Click to expand...

Hour, if you get a slightly larger box and use 1 inch (25mm) XPS foam insulation you'll be even more surprised at how much lower the heating pads are used!
I'm planning on using XPS foam insulation in a battery box for my cargo trailer -> Toy hauler conversion. XPS foam insulation has a compressive tolerance of 15 lbs per sq inch - pretty impressive strength.
 
12/24v thermo switch with controllable on/off 0-100 degrees C. $16.40

12v Heating Pad 40-140 degrees F. $12.99
Heating pad defaults to 40 degrees F when it turns on. You can manually adjust it much higher.

This is what I plan to use along with good insulation. Seems a much cheaper solution. Does anyone see any issues with this plan?
 
ERNWA said:
12/24v thermo switch with controllable on/off 0-100 degrees C. $16.40

12v Heating Pad 40-140 degrees F. $12.99
Heating pad defaults to 40 degrees F when it turns on. You can manually adjust it much higher.

This is what I plan to use along with good insulation. Seems a much cheaper solution. Does anyone see any issues with this plan?
Click to expand...

Shipping on the thermostat was a LOT. I would find a better heating pad, one designed to be attached to a battery.
 
HRTKD said:
Shipping on the thermostat was a LOT. I would find a better heating pad, one designed to be attached to a battery.
Click to expand...
Wow. I didn't notice the shipping costs. I'm sure I can find an alternative with a similar price range. Thanks for the input!
 
This is the thermostat that many of us are using. I bought it based on a recommendation from a forum member.

Amazon.com: LM YN DC 12V Digital Thermostat Module -58℉ to 257℉ Fahrenheit Temp Display Temperature Controller Board With 20A Relay Waterproof Sensor Probe Dual LED Display Red Blue: Home Improvement

Amazon.com: LM YN DC 12V Digital Thermostat Module -58℉ to 257℉ Fahrenheit Temp Display Temperature Controller Board With 20A Relay Waterproof Sensor Probe Dual LED Display Red Blue: Home Improvement
www.amazon.com
 
Will Prowse said:
If you are trying to use a lifepo4 battery in freezing cold temperatures, battle born just released a 12v heat pad for keeping the batteries warm without melting the case. This pad should work for any standard lifepo4 battery. Just slap it under your batteries and connect it to 12v and you are done.

I think it is over priced though. It can be found here: Click Here for battle born heater pad


If you cannot afford the battle born pad, you can use a septic tank heater pad. It works in the same way but may possibly melt your battery case if you are not careful. You can avoid this by adding some protection or a way to distribute the heat across your entire battery bank. I would personally put the batteries in a insulated container, then add a thin sheet of conductive material like sheet aluminum over the pad so that the heat it produces can warm up your entire battery bank.

Cheaper heater pad source: Click here for heater pad
Click to expand...
$200 for a heating pad is absurd.

I just made a serviceable heat chamber for my LiFePO4 cells using one of these:

The FermWrap™ Heater | Fermentation Heater | 40 watts | 115V | MoreBeer

The FermWrap Fermentation Heater is a carboy heater that can be used to help you control fermentation temperatures. A simple yet effective and reliable fermenter heater, the FermWrap also qualifies for free shipping!
www.morebeer.com www.morebeer.com

And for those of us comfortable shopping for bargains through AliExpress, you can get these 40W heating pads for under $8:

 
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fafrd, many of us heating our batteries are in an RV. 110v AC isn't (regularly) available, so we're using 12v heating pads.

That "nifty" gadget costs $179! I'll stick with my $10 thermostat.
 
HRTKD said:
fafrd, many of us heating our batteries are in an RV. 110v AC isn't (regularly) available, so we're using 12v heating pads.

That "nifty" gadget costs $179! I'll stick with my $10 thermostat.
Click to expand...
Yeah, the fancy dual-control gizmo is intended for 120VAC so unless there is a large market for brewing beer out of RV’s, the same class of technology may not exist for DC power (which just means you’ll need two devices and two temperature probes).

And yeah, cost direct through retailers like MoreBeer is always going to be a lot more than you can find shopping through AliExpress or eBay.

My main point was to be sure everyone here was aware that temperature control both ways can be achieved relatively easily and inexpensively (all motivated by Will’s link to a $200 heating pad!!!!).
 
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fafrd said:
My main point was to be sure everyone here was aware that temperature control both ways can be achieved relatively easily and inexpensively (all motivated by Will’s link to a $200 heating pad!!!!).
Click to expand...

In Will's defense, anything from Battleborn is going to carry a premium price. Plus, it's specific to their battery.
 
guyroch said:
Can these Facon Heater Pad handle the weight of a 50lbs 200AH SOK battery? Can I sit the batteries on these pad and is it safe to do so?
Click to expand...

I would err on the side of caution. Those pads are not designed to bear weight. They are intended to be stuck on the bottom of water tanks that are suspended under an RV.

Contact the manufacturer for clarification.
 
HRTKD said:
I would err on the side of caution. Those pads are not designed to bear weight. They are intended to be stuck on the bottom of water tanks that are suspended under an RV.

Contact the manufacturer for clarification.
Click to expand...

Thanks for this. This is what I thought. Perhaps the better approach would be to place the batteries on an aluminum sheet with a gap underneath and stick the heat pad in that gap, this way the pad heats the aluminum sheet with in turn it heats the batteries.
 
I have pads on the long sides of my batteries. That is working well. I had pads made to fit the sides exactly. The pads do not have thermostats in them. Instead, I use a thermostat on a circuit board which has a temperature probe that sits on top of my battery. More details can be found in my write-up thread:

diysolarforum.com

LiFePO4 Battery Warmer Install

This is my install of a custom set of battery warmers from Ultra Heat. I had contacted them through email asking about a warming profile for LiFePO4 batteries. They responded with a design to my specifications, including warming pads that fit my batteries exactly. While I initiated the...
diysolarforum.com diysolarforum.com
 
guyroch said:
Can these Facon Heater Pad handle the weight of a 50lbs 200AH SOK battery? Can I sit the batteries on these pad and is it safe to do so?
Click to expand...
Hi, I just put one of this facon pad under a 1/4 inch aluminium plate, with spacer to avoid any weight on it, over it I put 16 battery 280 amp lifepo4. Insulated box of 2 inch styrofoam. The box was outside for 24 hours at -20 celcius (-4 fahrenheit) . The temps inside the bos stay a 7 celcius (44F) and built-in thermostat do the job just well using 108 watt for 22 hours. But .... the pad died (open circuit).

After this event I read about the pad, and lot of fail story after few hour of heating in the review from buyer.

The power driving the pad was 13.4 volts and 5 amp current limitation from a riden 6018 power supply.

Going forward with 120 w silicon head pad with 2 channel électronic thermostat (reading aluminium temp and top of the box temp)

more to come

My advise: stay away from facon pad
 
Whinny said:
Don't know how well they would work but an option for elements may be motorcycle grip heaters. They are durable and easy to source.
Amazon.com: Universal Motorcycle Grip Heated Pads 12V Heated Grips Inserts Handlebar Hand Warmers Set: Automotive
Click to expand...

For that specific product, at the low setting of 45°C it's way too hot for direct contact with a LiFePO4 battery. Even if it was offset from the battery, it's still probably too hot. I would want an independent thermostat. Like smoking meat, you want the heat on your batteries to be low and slow.
 
I agree. I was only suggesting them as an element, would not use them without a controller of sorts...........
 
HRTKD said:
For that specific product, at the low setting of 45°C it's way too hot for direct contact with a LiFePO4 battery. Even if it was offset from the battery, it's still probably too hot. I would want an independent thermostat. Like smoking meat, you want the heat on your batteries to be low and slow.
Click to expand...
I was very happy with the performance of the 40W carboy heaters.

They take 120AC so not usable if relying on DC power from the battery but if AC is available, easy-peazy.
 
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