Small Cabin

Hope you reach your Kickstarter goal. If you haven't chosen your LCD supplier, check out my former company: https://www.crystalfontz.com/
They can get virtually any kind of LCD display and modify it in virtually any way you require.

Just checked out Eletrodacus's website http://electrodacus.com
lots of interesting information to be sure and we can never have enough of information.

hi electrodacus. i have followed your build for some years now. since you started your home build.

your solar controller / bms for lithium. I am looking at 4 700 amp winston cells for my off grid home. i use about 2.5-4 kw daily depending on how much sun I get (1.5 when it's really dark cloud).

My record is 6 kw. and I plan to break that this year.

I use only 120v ac. I have a TBS inverter that has very low idle draw. And the electric fridge, microwave etc appliances are much cheaper in ac than dc.

So my question is how your bms works. how are you balancing your cells?
thanks. and welcome. I am very happy to see your lithium set up.

i have 2 1kw arrays. The panels are big 48v (57 voc). I can program my mppt ts-60s for lithium easily enough. (they have a new firmware upgrade. it is even easier to do custom programs now. the firmware upgrade knocked out my old settings. It took about 5 minutes to put my custom settings for my crown batteries back in).

my lead acid battery pack is now going into year 5. it was much better this winter as I kept it above 0C. But it's definitely a PITA. You lose so much capacity in the winter.

It's interesting to see you using nearly as much power as I do with a (in 12v) 200 amp hr set up. Nice.

How deep do you discharge your GBS batteries? Do you have a generator supplement?

I'd be interested in your opinion of their solution.

In winter I have to heat my batteries. I originally built my camp for 3 season use. The batteries are in a separate building. I have insulated them (about r40 now) so they self heat to some degree. when it's -30 I put a propane radiant heater on them. PITA. I am thinking if I was to use LifePO4 I could insulate, close up and add a small electric heater.

I am always gobsmacked when I see the dod people run on their lithium batteries. 90% dod. A far cry from the 20% I try to keep to.

Creeky,

As far a battery heating goes as long as your battery shed is insulated well you can do as I did, pipe in the heat from the house to your battery shed, in my case I just use a retired power supply fan from a computer, draws 2 watts at 110 and keeps the batteries comfortable.

A Lead Acid needs external venting so is almost impossible to keep warm (you need more energy to keep it warm than you use from the battery)

With LiFePO4 is not a problem since no venting is required you can completely isolate the battery and use a low power electric blanket inside to keep the temperature at a set point.

I'm in to energy efficiency and with Lead Acid in my climate the energy needed to keep that warm and also do venting will have been much larger than what I will have used from the battery so electric heating will have been impossible.
And using heat from the house is also a bad idea in my case since is still energy and I'm not willing to use more energy to heat the battery than I get from it.
My house will be heated with electricity for PV panels so heating a vented battery will make no sense.
Having the battery inside the house with no need for venting requires no energy and battery is at the exact temperature it likes to be the most same as humans prefer

That may be true where you are but in the Pacific Northwest where winters are a bit milder is has performed very well, this past winter my batteries never went below 61 degrees and have performed very well, keep in mind my total energy use over 24 hours on the worst days was under 180 watts.

sadly my batteries are in the solar shed 200 ft from any heated room. I will say that this winter I tightly wrapped my batteries in 3" of polyiso inside the R25 insulated shed and the heat they create charging and discharging keeps them between 6 and 10C. I also close the vent unless equalizing. Until we hit that -20 to -30 time; then it's out with the heater for a couple hours every other day. It's been over a month since I needed supplemental heat.

on thing about ontario. it's not actually that cold during the "bad" heavy cloud season. the coldest weather actually sees quite bright sunny days. so that should help.

finally: the best derate info I've found is 7% on the lfp. 25 to 0* (*could have been colder) C. that was from a source in australia. a far cry from 50% for lead acid.

noted: If I could put my batteries in a heated/vented location near my living space, as I heat partially with wood (free), the cost would be quite low.

How are you planning to use PV for heat. Directing the energy directly to resistance heaters? And for overnight some sort of "mass" storage?

Now I heat the same concrete slab with hot water from the propane heater and I can have even a few days in winter without any heating with just a few degrees drop in temperature.

ethylene glycol

Saw you setup in you video, you built the place right and spotted the tubing you laid before the concrete for the in floor heating, question...you mentioned you were using water in your system and wondered if it worked as well as ethylene glycol for heat retention and freeze resistance

Don't use that; it is toxic. Use propylene glycol; non toxic in case of a leak or spill. It is the law for good reason.