How to build a LiFePo4 battery bank.

[StirCrazy]

A lot of people dont have any idea how easy it is to build a DIY LiFePo4 12V battery so I'll post a deicent video of how to do it so people can decide for themselves if it is in there capability.

this video is pretty decient on how to do it, what is missing is some sort of case. the Prismatic cells like to be clamped togeather slightly if you going to be running high currents. I have seen cases made out of wood with threaded rod providing the pressure, and several other ways also.

also I am not a fan of the BMS he uses, there are lot better ones, but he explains he needed the high capacity one to do a torture test on the cells.

so he builds a 280Ah 12V battery in this video, if you need more you could build 2 and then just tereat them like two 12V batterys and run them in parralell, or just build it all in series and do a 24V set up if you want to do the higher voltage systems.

280Ah LFP build

Steve

[time2roll]

I plan to use two Overkill BMS on two parallel batteries. 240 amps continuous. I believe Overkill will surge 130 to 150 amps for a few seconds.

[StirCrazy]

otrfun wrote:

FWC wrote:
. . . There is well supported and easy to use bluetooth enabled BMS available from Overkill Solar:
Overkill 120A BMS
Also available for much less from the manufacturer:
LLT Power the OEM for Overkill Solar BMS

Overkill BMS's seem to have a very good rep; however, to my knowledge they don't make BMS's larger than 120a. For those who have 2000-3000w inverters with 200-300a current requirements what options do they have? Daly makes a few 150-250a models, but they have a somewhat sketchy rep. I suppose one could parallel multiple Overkill 100-120a BMS's and LifePo4 battery packs.

thats what I would do. I would rather run two 280 ah batteries in parallel using two BMS than run a larger daly. to many failures on there bluetooth models.

Steve

[FWC]

otrfun wrote:
Overkill BMS's seem to have a very good rep; however, to my knowledge they don't make BMS's larger than 120a. For those who have 2000-3000w inverters with 200-300a current requirements what options do they have? Daly makes a few 150-250a models, but they have a somewhat sketchy rep. I suppose one could parallel multiple Overkill 100-120a BMS's and LifePo4 battery packs.

Running several in parallel is not a bad idea, it would be the same as running several drop in batteries in parallel. It spreads the load (and heat) across multiple devices, and provides redundancy as well. On the down side, you would need to look at several screens on the app to see what each pack is doing, but that is not a huge deal. If you are handy you could also merge the data from each BMS into one stream as the protocol is open source.

To give credit where credit is due - these are not Overkill Solar's BMS, they are just retailing/rebranding LLT powers BMS.

[otrfun]

FWC wrote:
. . . There is well supported and easy to use bluetooth enabled BMS available from Overkill Solar:
Overkill 120A BMS
Also available for much less from the manufacturer:
LLT Power the OEM for Overkill Solar BMS

Overkill BMS's seem to have a very good rep; however, to my knowledge they don't make BMS's larger than 120a. For those who have 2000-3000w inverters with 200-300a current requirements what options do they have? Daly makes a few 150-250a models, but they have a somewhat sketchy rep. I suppose one could parallel multiple Overkill 100-120a BMS's and LifePo4 battery packs.

[Freep]

theoldwizard1 wrote:
For those on a budget, these weed grade B cell and the author did make "studs" to use on the screw in terminals that were not in the best of shape. Cheap fix !

For any of the prismatic cells I highly recommend installing studs and securing them with loctite. The aluminum they use for those terminals is VERY soft and it's easy to strip them out. Even with the studs you want to be careful not to over torque.

[Freep]

There's a guy over on DIYsolarfoum who is selling a bunch of 700AH Winston batteries his company bought and then realized weren't right for their project and now they're trying to get them off the books. I'd buy 4 if I had room in my battery compartment and sell my current 271ah pack. These batteries can charge well below freezing.

https://diysolarforum.com/threads/700ah-batteries-for-sale-brand-new.20314/

I have no financial interest in these cells or DIYSolarForum. I just hope someone is able to take advantage of a good deal.

[StirCrazy]

pianotuna wrote:
How much for shipping?

that was included in the price per cell. of course there is a minimum of 4 cells per order and the more cells you buy at ones the lower the price. that other place wanted 740 for 4 cells and 1300 for chipping, which is a huge rip off. that what what you expected about 2 years ago.

Steve

[pianotuna]

How much for shipping?

[StirCrazy]

pianotuna wrote:
Email them and ask. And their price may be competitive with roll your own.

Na, the whole point of roll your own is to be able to pick the BMS you know is quality and has the features you want, and the manufacture of the cells. the dealer above is only one of many, for some reason there is no extra shipping to the US but there is to Canada, but there are dozens of distributers and lots include shipping. I think the one I found was aout 178.00/280ah cell order of 4, shipped to canada. they drop it to 137/cell if your buying 16, but there prices are always moving a bit so Ill sww what they are when I actualy put my order in. I am just trying to figure out how many I am ordering right now. I need to empty the front storag on the 5th wheel and see how much work it would be to relocate the batteries from the very front to just behind the storage where it is part of the heated basment. if I get 16, I could put 840AH in the fith wheel and 280 in the camper. that woul dgive me roughly 4 times the usable AH in the 5th, and almost three times what I have in the camper. but that could be another thing I have to sort out, I use the camper more in the sholder seasons when I am doing my own thing so even though it has 325 watts of solar a few cloudy days with only 105 usable Ah messes things up when you need the furnace on. so the other option might be to go even and 560ah in the 5th (2.3 times the present capacity) and 560ah in the camper. or maybe I look at getting 20 cells.. I have the luxery of time as the GC batteries in the camper are only 1 year old, and even though the GC's in the 5th wheel are in need of replacment they still hold good enough thanks to the solar, so I can watch prices and buy when they drop again.

Steve

Steve

[pianotuna]

Email them and ask. And their price may be competitive with roll your own.

[StirCrazy]

pianotuna wrote:

StirCrazy wrote:


did they charge shipping seperate, I just looked at them they want 738 cdn for the batteries then 1300 shipping LOL... got to love thoes rip off guys. but 310AH nice.

Steve

Try these folks instead:

Alberta.Lithium1@gmail.com

for what? they only sell premade batteries.

Steve

[pianotuna]

StirCrazy wrote:


did they charge shipping seperate, I just looked at them they want 738 cdn for the batteries then 1300 shipping LOL... got to love thoes rip off guys. but 310AH nice.

Steve

Try these folks instead:

Alberta.Lithium1@gmail.com

[time2roll]

Shipping was included. They did add CA sales tax.

[StirCrazy]

time2roll wrote:
My first cells should arrive late this month or next.

did they charge shipping seperate, I just looked at them they want 738 cdn for the batteries then 1300 shipping LOL... got to love thoes rip off guys. but 310AH nice.

Steve

[time2roll]

My first cells should arrive late this month or next.

VariCore 3.2V 310Ah lifepo4 battery DIY