Dragonfly batteries in winter storage

[Fishhawk1650]

I had an interesting conversation with a person at a Keystone dealer a couple months ago. I was dropping off my 23MLE for some minor work and he noted that I turned off the battery and the solar panels.

It was about 15 degrees that day and I said it's that way so the batteries do not take a charge below 32 degrees since that degrades the batteries.

He said, I could consider turning on the solar panels and run the battery heater to keep the batteries topped off. I guess if I send power only to the electrical system and not the batteries, that would be ok, but this is in storage mode on the side of my house and I generally do not need power unless I need to open the slide to access something.

I'm looking for what experienced users do with lithium batteries (besides remove from the coach) in freezing zones.
- I'm guessing the battery heater is electric therefore solar should assist, but don't know how power hungry the heater is and if 400w panels would do the job. Of course that's assuming the sun is out and the coach isn't covered with snow. I'm in Colorado so there's rarely a shortage of sun.

- If I leave the battery turned off and have the solar on and/or have shore power, will I be safe to have full power access and not risk damaging the batteries?

It would be nice if the solar had a smart control to trickle charge the battery ONLY when the temps are above 32 degrees.

Many thanks in advance for sharing your advice and experience.
Cheers

[NH_Bulldog]

I strongly suggest going to the Battle Born website (manufacturer of DragonFly batteries) and also check out the Keystone website. There is a lot of great information on the LiFePo4 batteries on both sites, including what to do with the batteries in the winter. For what it’s worth, 41°F is the magic number, not 32°F. But fully charged and fully disconnected, they can tolerate sub-zero temperatures as long as you are not charging or discharging).

[Stircrazy]

the only issue I see with that is the heater trying to keep the batteries warm at night when you have no solar contrubution. you could try it and check on your state of charge in the morning then again around supper time (before it gets dark) for a few days just to make sure the solar can keep up with the heaters demand. personally I would just pull the cables off the battery when stored so the parasitic loads are not draining it faster than its natural loss

[Gemde]

I turned off the Dragonfly batteries with the battery disconnect switch in November. Tuned them back on to check them last week. 100% charged, despite being in the freezing weather all winter!

[Fishhawk1650]

I was able to find the manual for the 100ah battery. It says the battery management system on the battery will prevent charging below 32 degrees and will allow discharge down to -4.
https://dragonflyenergy.com/wp-conte...3_09062022.pdf

That’s nice piece of mind that it has on board protection. I’ll still keep power off when it’s cold to be safe. I guess I could keep power on it and let the BMS manage it but why risk it if it’s not necessary.

[Greggde]

Battle Born is probably the most reliable source of information for your queries