Recommend me a battery y'all? Parts recommendation?

[Rednecktek]

OK, so I really don't want to have to use WallyWorld batteries in my camp (5760 usable WH), but because it's below freezing for 4+ months a year out there I can't really use LFP's without forking out the $RealMoney AND making heating systems and such...

OK, so as a thought, if I did get the cash to do it, what about this idea:

My battery shelf is 24" x 48", so I can lay a couple of rackmount (19") batteries on the shelf, thinking a pair of the 200Ah 24v for 9600Wh (3Kw 24v system)
That would leave me 2.25" of space on either side and I could get the 2" mylar coated hard foam insulation and make an insulated box all the way around.
I would need to get a few of the 12v heater pads to put on top/middle/bottoms of the rack, I'm thinking 6 or 14 pads?
I will have my 4 old 120Ah FLA batteries, 20a SCC and 200w of panels that are currently up there.

I guess what I need input on would be:
1: Best budget/cost effective (I.E. not Victron/Outback/MidNite) way to control the heater pads
2: Which pads to use
3: How many would I need
4: Which bang for the buck rackmount 24v battery with cold weather protection AND 200a BMS/breaker (that's actually in stock somewhere and doesn't cost a spleen to ship)
5: How to "wake up" the battery once it shuts itself off

A pair of these batteries is going to be about 1/3-1/2 of my annual "Play Money" that has to cover anything I want to do at camp (hot showers, guest cabin, well backup, etc), any toys I want (my computer is an old I7-3770, food & gas while I'm home), any vacation I want so it's got to be as cost effective as possible. I don't need bluetooth or internet access or car washing or dog grooming (my cat would object to that!) so no need to spend the extra for those features. The cabin is unattended for 6+ months at a time and I think I'll need to just shut off the breakers when I leave, right?

Having said that, I don't want to DIY a battery for this project, I just don't feel comfortable doing that just yet, maybe after I've built some smaller batteries first. I know, WUSS!!

I'm sure other people here have done something similar, how did you do yours? Any tips you can give me? Troubles you've had? Any rumors about higher capacity batteries since we have 160 and 280Ah cells out there?

 

[wmgeorge]

When you close your camp down for the winter, disconnect your LiFePOs place on a two wheel cart and transport them home in the back of your pickup.

 

[Rednecktek]

When you close your camp down for the winter, disconnect your LiFePOs place on a two wheel cart and transport them home in the back of your pickup.

That's not gonna work if the family goes up and I'm 9000 miles away on a ship, they'll be left in place.

 

[Supervstech]

I’m curious of the specs on the batteries you chose… 9600Wh? 400Ah @25.2V should be 1080Wh

 

[Rednecktek]

OK, let's see how I messed up the math...

24v * 200Ah = 4800Wh
2x batteries * 4800Wh = 9600Wh

That's what I was working with, but also beside the point as I'll live with the extra 480Wh.

 

[acdoctor]

Are you thinking of using the existing stuff to keep the new ones warm?
What do you think the low temperature of the shelf could be?

 

[Rednecktek]

Are you thinking of using the existing stuff to keep the new ones warm?
What do you think the low temperature of the shelf could be?

Yeah, I was thinking of recycling my old 12v system to power the heaters and some LED motion detector lights in the utility room (so you can see to turn everything on when you get there at night) since I already have the parts.

The utility room is sheltered from wind and rain mostly, but there's no way to insulate out there (and be able to do ANYTHING else, like eat) and being on the Washington/Idaho/Canada border it's regularly well below freezing for 4 months at a time. I've seen single digits F a time or 3.

 

[wmgeorge]

That's not gonna work if the family goes up and I'm 9000 miles away on a ship, they'll be left in place.

So people go up in the Winter time when its cold even if the cabin is winterized? Its on the Washington/Idaho/Canada border it's regularly well below freezing for 4 months at a time. I've seen single digits F a time or 3.

 

[acdoctor]

Use RV tank heaters ( they a available in several wattages) don’t trust built in thermostats. Wire through separate thermostat. Perhaps more than one assembly set to come on at a few deg apart. Use 3 inch’s of foam every where that is possible. Mechanical thermostats are the most reliable.

I used 1 inch foam on all sides and 2 10 watt heaters to keep 2 200 ah LFP’s 50 deg outside during a period of time that highs were 30 deg F. And lows near 0 deg F. In the the mornings they were near 40 deg F. More foam was needed.

 

[Rednecktek]

So people go up in the Winter time when its cold even if the cabin is winterized? Its on the Washington/Idaho/Canada border it's regularly well below freezing for 4 months at a time. I've seen single digits F a time or 3.

I'm usually only home between Jan and March which is when I get to use my cabin. If I'm lucky/unlucky It'll be warm enough to have running water. Ultimately I'm hoping my nephews will start going up there, but they bitch about the 7hr drive each way.

Use RV tank heaters ( they a available in several wattages) don’t trust built in thermostats. Wire through separate thermostat. Perhaps more than one assembly set to come on at a few deg apart. Use 3 inch’s of foam every where that is possible. Mechanical thermostats are the most reliable.

That's my thought but I have no experience with those heater pads so I'm looking for recommendations on which pads and thermostats to use. I'll be using 2" foam on all sides because I can't fit anything thicker in the space available.

I'm not sure if I just need 2 pads on each top, middle, and bottom to provide enough heat or if I need to do that AND put 1 or 2 on each side of each battery, hence the 6 or 14 question above. I think it would depend on the size of the pads in square inches vs the surface area of the rackmounts.

 

[Supervstech]

Also, keep in mind to seal the insulation together. Air gaps are the worst for insulation.

 

[Supervstech]

I think if there is direct contact between the cells and the insulation, a heater pad will be needed on that wall, if the cells are suspended, and not contacting the walls, a single heat pad should be sufficient on the floor of the box.

 

[Supervstech]

Eastern Washington is a great place. I miss living there. Lived in Cheeney for 4 years.

 

[Rednecktek]

I think if there is direct contact between the cells and the insulation, a heater pad will be needed on that wall, if the cells are suspended, and not contacting the walls, a single heat pad should be sufficient on the floor of the box.

Not sure how rackmounts are built inside, but by my math there's going to be about 1/4" on either side of the battery to the foam, nothing on top, bottom, or back, but I'm sure I'll have a gap in the front for the wiring and an access door to turn the breakers on and off.

 

[Rednecktek]

Here's another question, and I should ping @RichardfromEG4 and ask: If the general cutoff between going from a 12v system to a 24v system is 2Kw, and all the AIO's out there for 24v are 2400-300w which would be 100-150a draws, why are all the 24v rackmounts a 100a BMS's & breakers?
That means I can't run a 24v system at load with one of your batteries. Is there a reason manufacturers don't use 200a BMS/breakers for those?

Sadly that rules out EG4 products for me.

 

[Solar Guy Richard]

Here's another question, and I should ping @RichardfromEG4 and ask: If the general cutoff between going from a 12v system to a 24v system is 2Kw, and all the AIO's out there for 24v are 2400-300w which would be 100-150a draws, why are all the 24v rackmounts a 100a BMS's & breakers?
That means I can't run a 24v system at load with one of your batteries. Is there a reason manufacturers don't use 200a BMS/breakers for those?

Sadly that rules out EG4 products for me.

I'm sure theres a reason....I just don't know off the top of my head. A lot of people get by with a single battery, but honestly most people are buying 2 or more batteries and doubling their amp draw capacities. That being said - our BMS actually uses a pretty universal connection ribbon cables, so a lot of people I've spoken to with this concern buy our batteries (because the price and form factor is just absolutely amazing) and then get an overkill BMS (which has the exact same ribbon cables) to replace it. Although this technically voids the warranty, when people see the quality and see the cells are A+ rated they know that the battery is likely to die due to aging rather than a manufacturing error.