My son was up this weekend and he finished putting in the 2" x 6" ceiling joists and the R-30 Insulation in the roof of the solar power shed.
Readers may recall that a couple weeks ago, when the temps went down to -3°F here in northeast PA, the battery temperature of the Lithium Iron Phosphate battery rack dropped down to 28 or 26 degrees.
That is perfectly fine for the batteries to continue supplying power, if they had to, but definitely NOT OK if any charging is, or might, take place.
Apparently, when Lithium batteries reach 32 degrees, if you try to charge them, it __could__ result in something called "lithium plating."
From Google:
Lithium plating is a process that occurs in lithium-ion batteries when lithium ions build up on the surface of the anode instead of being inserted into the graphite particles. This can happen when the battery is charged too quickly or at a low temperature, which can cause the lithium ions to move too fast or too slowly, respectively.
Lithium plating can have a catastrophic impact on the battery's performance, safety, and lifetime. Some signs of lithium plating include: A gradual decrease in discharge voltage and An increase in anode resistance.
Lithium plating can be prevented by charging the battery at the right temperature, which is between 41°F and 113°F (5°C and 45°C). If the battery is being used in an electric vehicle, it may not be possible to charge it within this temperature range, so it may need to be pre-heated.
I wonder how many TESLA Drivers knew about THAT little gem of inconvenience when they bought those pricey electric cars?
Anyway, at the time, we put a "Torpedo" heater in that shed. It ran off kerosene and we were able to select a temperature of 50 degrees on the heater's thermostat to keep the shed warm.
By the way, the "shed" is a cement block building, with rebar, bond-beams, and a cement roof. The roof was poured onto galvanized, corrugated, steel. So the steel which was bare on the inside of the shed, acted as a sort of heat-sink; causing any heat in the shed to just flow out of it.
Last weekend, we bought a "Froth Kit" and applied spray foam to the inside of the roof, totally covering the exposed metal. That would serve to "break" the heat-sink. But spray foam only has an R-value of about 1 or 2. So we also bought 2" x 6" lumber to put in an actual ceiling, with R-30 fiberglass "bats" between the joists. That's the work we finally got done this weekend.
So now, we're as ready as we know how to be for this "Polar Vortex" that's already arrived into the central USA, and which is forecast to affect pretty much the entire east coast this week.
I still have the "Torpedo" heater if needed, but with all the new insulation, it may NOT be needed. We'll just have to wait and see.
You know, when I decided to go with this solar stuff, it was a STEEP learning curve. I thought we had gotten through it, until the intense cold came a couple weeks ago. The learning curve cropped-up again.
Lucky me!
/sarcasm
