Winterizing lithium batteries

[rhodedog98]

How do I winterize my lithium batteries or do I have to. The temperature is starting to drop at night. I read if fully charged they only lose 3% per month.

[pianotuna]

EMD360 wrote:
I guess I could just disconnect the negative and suspend the mifi service for the winter. At least a couple of months. Isn’t that too simple though?

Nope it is a great example of the KISS principle. (Keep it Simple {I'm} Stupid)

[EMD360]

I guess I could just disconnect the negative and suspend the mifi service for the winter. At least a couple of months. Isn’t that too simple though?

[3_tons]

EMD360 wrote:
This is the first winter for my lithium batteries. I bought a temp stick to monitor the temps in the battery compartment. https://tempstick.com/ Temp Stick I added a WiFi line to the rv to read temp and solar plus battery info remotely. But I’m not sure how to deal with winter.
I won’t take the batteries out. The wiring is far too complex and too much work to just disconnect.
So far the low temp in the compartment has been at night so solar is not charging the batteries. We had one night at 30° but the compartment was 35°. The batteries have a constant load of about 9 to 11 watts. So the batteries are rarely below 95% charge. I could turn off the DC power but then could not monitor remotely!
I bought a battery warmer pad for the compartment even though it was not recommended for lithium batteries. It is thermostatically controlled to turn on at 35 but does not turn off unless the temp reaches 80°. It means once it turns on it won’t go off unless I control the extension cord with WiFi. I’m not sure why the upper shut off temp is so high. Instructions say to unplug it if the battery is warm enough.
So with my system not charging the batteries in the cold and having them depleted 10% is an issue over winter.

Not sure I understand?? If you’re not using the camper why not just disconnect one of the battery cables? The self discharge rate of LFP is extremely low and should get you through the cold season without any issues…

3 tons

[EMD360]

This is the first winter for my lithium batteries. I bought a temp stick to monitor the temps in the battery compartment. https://tempstick.com/ Temp Stick I added a WiFi line to the rv to read temp and solar plus battery info remotely. But I’m not sure how to deal with winter.
I won’t take the batteries out. The wiring is far too complex and too much work to just disconnect.
So far the low temp in the compartment has been at night so solar is not charging the batteries. We had one night at 30° but the compartment was 35°. The batteries have a constant load of about 9 to 11 watts. So the batteries are rarely below 95% charge. I could turn off the DC power but then could not monitor remotely!
I bought a battery warmer pad for the compartment even though it was not recommended for lithium batteries. It is thermostatically controlled to turn on at 35 but does not turn off unless the temp reaches 80°. It means once it turns on it won’t go off unless I control the extension cord with WiFi. I’m not sure why the upper shut off temp is so high. Instructions say to unplug it if the battery is warm enough.
So with my system not charging the batteries in the cold and having them depleted 10% is an issue over winter.

[StirCrazy]

pianotuna wrote:

rhodedog98 wrote:
Thanks everyone this clears up a lot of cobwebs for me this puts me in the right direction.

From a seller:

https://www.solacity.com/how-to-keep-lifepo4-lithium-ion-batteries-happy/

which is pretty much what I said with more explanation asside from the slant that Battleborn are the best 😉 I got my numbers from the cell manufactor instead of a sales page as I am always worried about sales misconscrewing the numbers to protect there warenty, which they very very often do, and I understand them if they can just slightly change the operating instructions a tiny bit and reduce the chance of a return by 80% its in therebest interest. some take this a little to far though.

there are also slight differeneces between form factors of the same chemistry, for examle cylindrical (battle born) pouch (nobody I hope) and prismatic (becoming more and more popular all the time due to the simplicity of building). most of the differences are in how wekk they can shed excess heat from charging and discharging which affects the rates.

Steve

[pianotuna]

rhodedog98 wrote:
Thanks everyone this clears up a lot of cobwebs for me this puts me in the right direction.

From a seller:

https://www.solacity.com/how-to-keep-lifepo4-lithium-ion-batteries-happy/

[rhodedog98]

Thanks everyone this clears up a lot of cobwebs for me this puts me in the right direction.

[StirCrazy]

rhodedog98 wrote:
Steve thanks but would the core freeze if they are left outside?

no they dont get hurt from storing them even fopr up to a month at -45C and up to a year to -35C. the numbers posted above are for usage at different temps, the battery must be above 0C to charge it and above -20C to discharge it.

if you get below -35C then I would thing about disconection it and brining it inside the house.

Once again PianoTuna is quoting numbers from older Li chemistry.. as long as it is not at 100% you will be fine, thats why I say discharge it to 90% and let the natural loss take it down while in storage. I even wonder what starting at 100% would do in all reality... even new smaller Li batteries that are shipped in stuff are normaly at 75-80% when you buy them now, not like 20 years ago when you bought a new cell phone and had to charge it over night before you used it.

Steve

Steve

[KD4UPL]

Have you checked the manufacturer's specifications for your particular battery? Everyone here is just guessing. Some lithium battery models say to not expose them to temperatures below -4F. If you expect temperatures that cold I'd be very cautions about leaving them outside.

[time2roll]

No water in a lithium battery to freeze, expand and cause damage. Disconnect and it is fine. Lithium is lighter and clean compared to lead-acid so bringing it inside for the winter should be less hassle. Bring it up to maybe 50 degrees before you place it back in service.

[Ivylog]

I would charge them to 13.2V (70%) and then disconnect them.

[pianotuna]

The Li dealers appear to recommend only 50% state of charge for storage.

Li hate being float charged, so turn off all sources of charging.

Freezing them is ok so long as there are zero parasitic loads.

Make sure they are well above freezing before charging in the spring.

[Lwiddis]

Storage at 100% SOC isn’t recommended by any RV Lithium battery manufacturers that I know.

[HMS_Beagle]

Pretty much all the manufacturers seem to state that storage down to 0 or even -20F is fine, but do not charge if below 32F. The more sophisticated lithium chargers will automatically shut down at 32, but to be sure, I'd disconnect them. That also eliminates the vampire loads that many campers seem to have.