I don't know this particular one, but what I've seen for a lot of LFP with the built in heating pads is that they can charge down to -4ºF. But, what this means, is that with the heater running, it can keep the battery warm enough to charge (above 32ºF) when the ambient temperature is -4ºF. This is not, in my mind, really a cold weather battery, but rather one that in the right conditions could be used where it might occasionally get cold. Like in an unheated garage that might bet below freezing occasionally, or if someone leaves the door open by mistake. Or for ourdoor use in moderate climate that might get into the 20's or teens a few times a year. But not for outdoor use on a mountaintop radio repeater or remote cabin in Montana where it's in the single digits for weeks.
Insulating the battery will obviously help a lot in trapping what heat that the built in heaters give off -- I've seen the heated ones work okay when in a highly insulated box (just like we used to build for lead acid all the time) and isolated from the concrete floor. But it also depends on the particular control logic, and whether you have grid power. If you have grid power to keep them warm they can work pretty well. For off grid, the heat is needed the most right when you have the lowest insolation, which isn't a good situation. And for control logic, I've seen two variations -- one is to run the heater from the battery, which insures that it stays warm... but risks tanking the battery fairly quickly (in a few days) from the heater load alone. The other variation is to only run the heater when there is a charging source for the battery -- which doesn't risk draining the battery, but also means that overnight in an off grid system there is no heat input, making good insulation around the battery even more important -- to keep the temperature above 32ºF by morning so it can accept a charge then -- otherwise you are limited to the charging source only running the heater for a while (several hours?) till the battery gets back up above 32ºF and can accept a charge, and by then you may have wasted a lot of your short winter sun hours.
Another thing to consider is what is the lifespan of the heating pad? If it's 3000 hours, then that will last a long time -- similar to the battery lifespan of 15 to 20 years -- when used a few hours a day during a few weeks a year. But if used in a climate where it needs to operate 24 hours a day for 3 or 4 months out of the year, the heating pad will wear out long before the lifespan of the battery. And then it's no longer a heated battery, and it's usually not possible to replace it, as it's built into thebattery too deeply. If you have a situation where you are doing a lot of heating, then using a external heating source in an insulated box can be a much better option.
If you are doing open loop operation of the LFP battery, having built in internal heaters can also be problematic. Both because it can throw off the accuracy of an external AH counting SOC meter, and because some charging equipment will not respond appropriately to the battery limiting incoming power to that required to run the heater when the temperature gets below 32ºF. Some charging sources will just rise to absorb voltage till the batttery warms and starts accepting a charge, when it falls to battery voltage. But some sources can spike and cause equipment damage if the charging FET's or relays on the battery are opened to prevent charging at low temperatures.
For actual low temperature operation, lithium titanate is the only technology I've seen that is really good -- full rate charge and discharge at -40ºF. Sodium ion can take lower temperatures than LFP, but not as cold as LTO. The products for both of these that I've seen have not been commercial successes due to much higher cost than LFP. Why by a real cold weather LTO battery for $1/watthr when you can get a heated LFP battery that claims to work at -4ºF, for only $0.20/watthr. Not understanding the limitations of the heated LFP batteries means that few people bought the LTO batteries instead.
Zeke
Message: 1
Date: Sun, 10 May 2026 13:19:31 -0600
From: Jay <[email protected]>
To: RE-wrenches <[email protected]>
Subject: [RE-wrenches] Low temp LFP
Message-ID: <[email protected]>
Content-Type: text/plain; charset=utf-8
Hi all
I had someone ask me about what eco worthy is selling. A low temp LFP battery. They say charging at -4?F
Is this actually something new, a new chemistry or just marketing?
Thanks.
Jay
