I have been looking around for options to replace the two lead acid batteries in the bow of my boat with lithium. But from my understanding charging below freezing is out of the question. Seems my only option is to either have it setup to remove the battery to charge when the temp is low. Or find someway to keep the battery above freezing.
Operating LiFEPo4 in low temp environments
- Thread starter Brownb56
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gnubie
Solar Wizard
- Joined
- Sep 20, 2019
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- 3,847
Heating is definitely needed if you want to charge in below 0c environments. There's been a fair discussion on here about using heating pads already. Here's a good starting point for you to read up on what has gone before.
diysolarforum.com
LiFePO4 heating pad for cold temperatures
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...
diysolarforum.com
Maast
Compulsive Tinkerer
Just posted this elsewhere here:
You can make a crude but effective heating for your LFP batteries to protect them in low temps for cheap: Put your new LFP batts in a cooler on top of a 12V heating pad (like a automotive dog bed heating pad).
Tape a temperature sensitive "snap disk" like this that activates at 35F & turns off at 45F and wire it in-line on the positive side between the battery 12v post and the heating pad. Do this in parallel with another battery in your pack, this will ensure that any one snap disk failing open will not allow your batts to get too cold. Use a bit of thermal transfer grease between the battery and your snap disks. If you want to get fancy you could even put a 12V pizeo buzzer in the circuit to let you know when the heating pad activates.
To guard against a snap disk failing closed I'd put a 12V adjustable temperature alarm to alarm if the batteries get too hot. It's unlikely though because snap disks are dead-simple devices and ultra reliable.
Batts get warm under use anyway and inside a decent cooler I'll think you'll find the heating pad very rarely activates.
You can make a crude but effective heating for your LFP batteries to protect them in low temps for cheap: Put your new LFP batts in a cooler on top of a 12V heating pad (like a automotive dog bed heating pad).
Tape a temperature sensitive "snap disk" like this that activates at 35F & turns off at 45F and wire it in-line on the positive side between the battery 12v post and the heating pad. Do this in parallel with another battery in your pack, this will ensure that any one snap disk failing open will not allow your batts to get too cold. Use a bit of thermal transfer grease between the battery and your snap disks. If you want to get fancy you could even put a 12V pizeo buzzer in the circuit to let you know when the heating pad activates.
To guard against a snap disk failing closed I'd put a 12V adjustable temperature alarm to alarm if the batteries get too hot. It's unlikely though because snap disks are dead-simple devices and ultra reliable.
Batts get warm under use anyway and inside a decent cooler I'll think you'll find the heating pad very rarely activates.
These are also dirt cheap and come in many voltages, I've used this one but many options on amazon. https://www.amazon.com/24V-Flexible-Polyimide-Heater-Plate/dp/B074SXKPZL/
I've been getting the temp switches on banggood.com searching "Temperature Thermal Controller" havnt found them cheap on amazon.
I've been getting the temp switches on banggood.com searching "Temperature Thermal Controller" havnt found them cheap on amazon.
Those seem perfect for the "snap disk"
Maast linked. Would be nice to see a review of the setup.
Maast
Compulsive Tinkerer
I was thinking they might give a hot spot and it would probably need a aluminum plate as a heat spreader.
Correct, the head pad sticker is on an aluminum plate with the batts on the plate. I have a "snap disk" at 15C, cuts the power to the heating pad. The snap disk is not attached to the to alum. plate its just hanging via the wire in the batt box. I am currnty using the LOADOUT of my solar charger in the streetlight mode. At night loadout turns on and the heater does its thing. It's a good 3 hour hike for me to access this system. I have a new device that I am taking up to better play with the temps, will take some pics.
Maast
Compulsive Tinkerer
If you try to charge in below freezing temperatures you plate elemental lithium to the electrodes and its pretty much instant irreversible death for the cell capacity. Its not actually at freezing, it's a little below that but its close enough you dont want to press it.
Is there any data about how much load can be applied to heat internally above freezing? Or how long does it take to internally freeze at a given temperature?
I had a lithium battery (shorai) in a 2nd hand racing motorcycle 7 years ago and I knew nothing about it. I started it bi-weekly in the winter out of habit. Sometimes night lows in the -10f range I would start it later that morning.
I had a lithium battery (shorai) in a 2nd hand racing motorcycle 7 years ago and I knew nothing about it. I started it bi-weekly in the winter out of habit. Sometimes night lows in the -10f range I would start it later that morning.
newbostonconst
Solar Enthusiast
- Joined
- Sep 24, 2019
- Messages
- 1,004
Here is a research article on battery temp to performance that is a good read. One highlight I got out of it is the running at colder temps they last longer but you don't get full output.
https://www.researchgate.net/publication/278708441_LiFePO4_optimal_operation_temperature_range_analysis_for_EVHEV
https://www.researchgate.net/publication/278708441_LiFePO4_optimal_operation_temperature_range_analysis_for_EVHEV
