Therehas to be somebody who has dealt with this. I know we have one guy >70deglat right now but I don't know if he ever did solar. Come to think of it,that's not a good place for solar! (unless you have REALLY big batteries). ...
I've got a remote access cabin about 65 N Lat - generation (3.3kw gas), Solar(200W @ 24V), Batt (24V, 140AH, WLA Calcium, 1.215), inverter/charger (120/240,3000W, 30A charger). So, I have a bit of anecdotal information. All this stuff is 20 years old, except the batteries, I bought them used, they are 40 years old.
The solar is kind of a joke, I don't think I get much of anything out of it. But it was cheap. I got four 50W cells for a $100 each (around 1998). They were surplus from a railroad remote signal project and I was standing in the right place at the right time. I don't leave them connected when I am not there because I don't have any faith the controller will shut off and not overcharge. I recall the controller was $35 mail order.
And I deal with WLA, AGM, the occasional Lithium Ion, and very infrequentlyLithium Polymer for my work.
So some of this is informed opinion - some is just anecdotal. I'll list references where I can, and note what is anecdotal.
As already said, if charged, 1.300sg batteries don't freeze until -70F. 1.215sg freeze around -27F.
https://mathscinotes.files.wordpress.com/2013/02/finalplot.jpg
Anecdotal: My 1.215 sg WLA don't freeze and break exposed to -40F. I don't go snomachining if it is colder than 0F, but the bats are okay when I get out in the spring. I clean the posts, charge fully every fall. Shut off the CB from the batts so the solar is disconnected. Couple of times I have been out in the winter, 0F to maybe 25F. Put the heat on the gen, started it up, charged the batts, and used them - all worked fine.
Lithium (any chemistry) and stationary storage applications:
My information here is based on applicaion papers, IEEE, battery mfg. Energy density is high, hence the comments about "bomb like". The following was delivered at a North American battery conference a few years back (no reference):
Lithium Ion batteries (used in laptops) energy density is approaching that of a hand grenade. The difference is the laptop battery is designed to give up it's energy over a few hours. The grenade is designed to give up the energy over a few miliseconds.
All the papers I have seen on Lithium chemistry batteries show short life, few charge/discharge cycles as compared to any Lead Acid chemistry. (no reference)
Anecdotal: Lithium ion will survive .9 trips to -40F. I murdered one phone batt and one radio battery leaving them out in the truck over night. I haven't tried them at -20F. They survive fine at 0F and warmer.
For stationary applications, energy density is possibly the least worrysome spec. We are not dealing with drones, phones, cars, or airplanes. Unless one is dealing with a short term, high power UPS, power density doesn't matter much either - that kind of leaves out the AGMs.
Dollars per watt, WLA is by far the best return
for stationary applications. And my research shows calcium, low gravity (1.215 - 1.225) give the best longevity. I certainly would not insulate. WLA do not like geting hot - especially while charging. And they generate plenty of heat while charging. AGM is worse. They are prone to thermal runaway (no reference)
Personal Opinion - Protecting WLA from cold ambient: (this response is for paid jobs, where I have to put a stamp on the dwgs)
For mainland America, anywhere the ambient worst case is warmer than -27F, don't worry about it. For upper penninsula Michigan (did I get that right?) and similar areas, don't buy low sg batteries.
Some data shows battery capacity decreases 1%/deg-C below 20C (not linear)
http://support.rollsbattery.com/sup...ature-vs-capacity-flooded-lead-acid-batteries
So, at -10F, the batteries are down to 60% of the 68F rating.
Interesting writing this. Don't know if it helped much
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