I bought 2 LifePO4 batteries recently, the prismatic ones that are box shaped.
I know I should get a BMS and/or balancer, but I’m struggling to find ones meant for small amounts of 3.2V cells. Everything is for at least 4 cells or for 3.6V batteries.
I may use 4 cells when I need around 12V, but I’d ideally like to use 2 or even just 1 cell at a time.
Ideally, I’d like to have some BMS that would work with 1-8 cells and works up to 100A (or 300A, which is the peak momentary drain my batteries are rated for).
Are there any ones like that I should look at?
That’s overkill for my use. But it means for testing, I just have to consider the battery’s limits and not the BMS. I could find a cheaper BMS when I know what a project needs.
Right now, just any advice is welcome. I’m a bit lost, because I’m too new on the subject to know what I should be looking for. I can’t even find good info on what brands of BMSs are reliable.
Yeah this…The end use will dictate a large part of your design.
Sounds like the details have yet to be nailed down and you’re in info gathering mode.
Some suggestions -
Put " LiFePO4 Batteries" in the search tool for this forum.
Go to Mouser.com and put “Battery Management” in the search bar. Pick your batt chemistry. Search narrows down to 2 primary manufactures - TI and Analog Devices. Go to their website and get the datasheets, app notes, eval kits, etc. This is just a starting point. There’s a lot of info out there. You can narrow down where, what you need to follow up on once you have more details on your project. Good Luck!
I have 2 main use cases for these batteries:
The first is to power a 3.3V or 5V arduino-type of project for a really long time.
The second, which is my current project is, to power some really powerful fans at 12V or 24V and have it be technically portable. This project is partially a joke, because I know the result is going to look impractical and be pretty cumbersome. A single one of those fans uses 90W when running at 24V.
Do you absolutely gotta have the energy density of lithium chemistry or would a pair of 12v gel cells get the job done? No bms / cell management needed. Charging ckts pretty simple.
I’m kind of designing this project with a goal of being as overkill as I can safely make it. So I’m starting with the batteries and working off their limits. I have 4 of the batteries now, and I think I’m gonna stick with that amount.
I have 1 fan that uses 30A at 24V.
I found a 25A 24V boost converter on Amazon. So my plan is to use that with the speed dialed down. I may just run it off the 12V the 4 cells make instead, which uses 10A. That’s already extremely powerful.
For the battery rating, I just want to use the batteries I already bought, which are 105Ah/336Wh with 1C charging/discharging and a 3C burst discharging.
This is the exact model: Docan LF105 (relevant spec stuff starts on page 8)
Thanks! I’ll give that a read.
And for the energy density requirement, kind of. I’m wanting the ability to carry this around, so it can’t be too big or heavy. The 4 LiFePO4 cells I have are already like 18 pounds and pretty big. I don’t think bigger than that would be very feasible.
Although at this point, I might be better off just making a battery backpack instead.