Solar charging Li-ion at below freezing

One of my unfinished projects is a solar charger for my outdoor (Wyze) cameras.
My wife is an animal lover and enjoys all the videos we get. Especially the cougars at night :astonished:

I wanted to be able to position additional cameras in areas away from the available outdoor power and camera mobility was the main goal of my solar charger project.

While working on the design today I found this disappointing tidbit:

Ah *^@! …thats a stab through the heart for this project.
You should not charge Li-ion batteries below freezing. Here in Utah that is most of the winter. Lead acid is the only battery chemistry that can charge below freezing.

So this brings to mind many questions and I need to do more research.

  • What about the RV’s that have expensive Li-PO batteries trickle charging during winter storage??
  • Does solar charging raise the internal temp of the battery and keep it from falling below freezing? Ok, what about when there is no sun.
  • I had read that Telsla batteries are made of an array of 18650 Li-Po batteries how do these cars batteries survive the winter?
  • I should charge my Ebike outside in the winter?

This makes me rethink my design. Should I just build a 12V power source and run a landscape lighting cable to the other areas of the yard with a regulator at the camera?
More difficult to install but simpler to maintain in the long run.

Tesla batteries have a heater that warms them up before charging.

If an RV has LiPo(should be LFP/LiFePo4) and all they need to do is bring it down to storage voltage level and disconnect it. No need to keep it topped off like Pb batteries required.

As for charging the LiPo in freezing, I would look at how much energy it would take to warm them to 33DegF(or the lowest rated temp) and see if there’s enough left over for charging or if you have to increase your solar panel wattage size.

Alternatively, how far down does the ground freeze where you are? The earth is a pretty amazing thermal battery; you could bury batteries in waterproof boxes deep enough to never freeze?

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I wonder if a heat pipe could be configured and mounted to the back of the solar panel so that not only does the initial electric power start warming the batteries, so does the heat from the panel.
Gotta wonder what commercial units like the game cameras use since I can’t imagine they spec them for only above freezing use. Or maybe they are only using swapable batteries, ie no charging.
Interesting problem.

Makes for a good chiller… I have to wait for the water in the pipes to warm up before a shower… :rofl:

@dougl I lived out at the game and fish shooting range for over a year and the game cameras out there used replaceable batteries. They used the same stuff up in the northern part of the state where it does get cold. This was circa 2010 … doesn’t get nearly as cold in Arizona as it does in Montana…


Utah’s max frost line is 30 inches :astonished:

I think I am going to think about a 12V underground wiring schema.
Seems by the time I add heaters and such it will be more complex than just an underground wiring system.
I could add a lead acid battery with solar charging but that would only serve as a backup to mains power so what is the point?
Landscape wiring is pretty cheap just have to dig some slots in the ground … which here is pretty hard and full of rock. I live on a bench below the Wasatch.


There might be an easy way to do it depending on how small you were thinking the battery will be.
A calculator might be handy to figure out how much it might pull from the solar panel and only turn the heater on when the panel is generating. Hopefully most of the solar charge current would be used to raise the battery temp and then when the pad turns off, the power goes to the battery.

Rube Goldberg is watching just for fun.

and there are lots of 12V heating pads of many different power output ratings. IIRC there is a thermal switch listed in the above video or possibly ( * One Battery Heater Switch (Part No. EV-V120-BHS $8.00 ea. Retail plus shipping). )

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I don’t know why the video in my first post will not play.

Its a video of a mountain line in my driveway.

It’s because it uses the H.264 video codec instead of the MPEG-4 video codec, even though the filename ends in .mp4 (an MP4 file isn’t limited to video encoded with the MPEG-4 codec, perhaps surprisingly given the name), and some browsers don’t handle that. Firefox on Linux doesn’t play it, though I can download it and play it locally just fine. Chrome shows the initial image in a player, but the player doesn’t actually play for me.

Video on the web is terrible. This is why there are so many video-sharing sites that automatically run video transcoders to make videos run on different hardware… :sob:

It’s this way because of all the patent grabs in video encoding, FWIW.

There’s a plugin for improving the discourse video upload/playback experience, but it’s just a front end for a commercial video transcoding/storage/playback system. So I don’t think there’s an easy answer. The Discourse folks just suggest uploading to youtube/vimeo/etc and oneboxing it.

If we had more video content, it would possible make sense to run a peertube node (along side our mastodon node) for video, but that’s a lot of work for me…

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I’m surprised there’s not a transcoder plugin to convert all video VP8 or something open source unless even open source doesn’t mean it’ll be supported( ala ext filesystems and Microsoft’s refusing to support anything not grown by Microsoft ).

I haven’t found one. I agree it’s interesting. Discourse does a lot of reprocessing of images, and it would easily correspond to transcoding videos. It might be because image reprocessing is relatively cheap (fractions of a second of processor time), but transcoding videos is really processor-intensive.

So it would make sense to have one available, but I also am not completely surprised that I didn’t find one so far.