Heat your Lithium Batteries

[Scramjet]

Several people have asked about heating Lithium batteries in unheated spaces. This is true especially for the cheap china batteries where the BMS does not have a proper low temp cutoff. Most of the cheaper china batteries suffer from this condition. None of us want to ruin our batteries even if they are cheap. Further, even for those with a good BMS that does cut off, you may want to camp and charge in below freezing temperatures.

The obvious solution for full timers is to install the system in a heated space. But for part timers who don't heat their rig full time it is a problem. It is enough of an issue that Battleborn has developed a heated battery solution that is now available (at a price).

So... I ran an experiment last night (and I love a good experiment). I ordered a cheap 12w silicone heat pad, a cheap temperature controller and some thermal adhesive tape from Amazon. I thermal taped the heat pad to the side of a lead acid battery, connected the temp controller to the negative post and put it all in a factory battery box. I then put the box inside a plastic storage tote overnight. To monitor the test I put an outside sending unit from a weather station on top of the battery. The controller was set to turn on at 5 degrees C (about 40 F) and turn off at 10 degrees C (about 50 F). After a 30 degree F night the morning temp on top of the battery was 52 F and the controller temp at the negative post showed about 46 F. It seems to be cycling and working!!!

Conclusions: It does work. I would test it quite a bit more before I trusted it to guard $1,000 - $2,000 worth of batteries. Battleborn does have an off the shelf solution. The energy consumption when on is about 1 amp. On time will depend on the ambient temperatures and the enclosure.

Concerns: Robustness and longevity of the design and connections. Power consumption. Thermal conductivity of the case. Tightness and insulation of the enclosure.

I hope this helped or encouraged others to try this as a potential solution.

Regards, Brian

[RickLight]

A couple of other brands of drop-in replacements have built in heaters. I can't recall their names at the moment, but Battleborn is not the first.

There are also aftermarket heaters specifically for 12V batteries.

[Scramjet]

A couple of other brands of drop-in replacements have built in heaters. I can't recall their names at the moment, but Battleborn is not the first.

There are also aftermarket heaters specifically for 12V batteries.

Rick,

I have not seen the other brands of heated lithium batteries but I am sure they are out there.

I have also not seen the aftermarket battery heaters. Mine is for more of a low cost DIY project. The heat pad was $9 and the controller was $10. I am planning on getting some low cost lithium batteries and with a good BMS so I will be using this for sub freezing camping. A side benefit is keeping the batteries charged in the winter via solar during freezing temperatures. Not as important as I keep the rig in the driveway and can just shut off the solar and disconnect the batteries but it is a nice benefit.

I will continue to cycle and test this setup for the next week or so to prove to myself it is a viable solution.

Brian

[RickLight]

https://www.wisebread.com/the-5-best...attery-warmers
or google "battery blanket"

[geotex1]

One thing I can offer is that the 12VDC pads for holding tanks are probably the only ones out there with any longevity. The good ones have integrated thermostat control.

[Scramjet]

https://www.wisebread.com/the-5-best...attery-warmers
or google "battery blanket"

Rick,

Thanks for the link. Those are all 120v AC plug in type heaters except one which is a thermal blanket. This project requires 12v for both remote camping and the better efficiency off battery power. They are not suitable for my application.

Brian

[Scramjet]

One thing I can offer is that the 12VDC pads for holding tanks are probably the only ones out there with any longevity. The good ones have integrated thermostat control.

Rob,

I looked at those first. Most are bigger and have greater power draw than I think I need. I suspect and I am hoping that these silicone heat pads are essentially the same thing but smaller. Right now it looks like 12w may be enough for the mass enclosed in a battery box and inside a compartment. I will find out. I plan on stress testing this extensively before I actually use it in the rig. Even then I will continue to monitor the temps until I am satisfied.

Thanks for the input,

Brian