Which JK BMS should I use for 24v, 8 cells LF280K?

[Quattrohead]

Some BMS can be run in series or parallel and some cannot.
A 200A BMS will be fine for you, it should protect itself if you happen to try and pull too much current.

 

[Horsefly]

Is it possible to successfully to create 2 8S EVE 280Ah based 24v batteries, and then series them to 48v, that is on the basis that I have 2 sets of active balancing going on at any one time 4A as opposed to 2A with a single JK 16s BMS.
Not sure of the rules here?

I'm not sure, but I think you are misunderstanding the balancing. If you have two 8S BMS's each with 2A of balancing, putting two in series will still only be doing 2A of balancing. They will only balance within their 8S pack, so nothing will be balancing across all 16 cells.

If you are making a DIY 48V battery, it is much better to make a single 16S battery.

 

[brianonmull]

I'm not sure, but I think you are misunderstanding the balancing. If you have two 8S BMS's each with 2A of balancing, putting two in series will still only be doing 2A of balancing. They will only balance within their 8S pack, so nothing will be balancing across all 16 cells.

If you are making a DIY 48V battery, it is much better to make a single 16S battery.

Hi, no my point is that the JK BMS is only having to balance 8 cells, so effectively at any point in time 2A across just 8 not 16 cells.
I suppose my worry was that perhaps the sensing might be an issue at the crossover from the 24v point to the next positive?

 

[740GLE]

Is the JK rated for 2S?

 

[740GLE]

Hi, no my point is that the JK BMS is only having to balance 8 cells, so effectively at any point in time 2A across just 8 not 16 cells.
I suppose my worry was that perhaps the sensing might be an issue at the crossover from the 24v point to the next positive?

Right but if you look at just 8 cells you get a
Max of 2A for those 8 cells. Same for the other 8 so it’s not like you’ll balance faster.

Also if you have cells that need more than 2a of balance current, you have bigger problems then trying to run two BMS in series.

Keep it simple for a 48v one BMS.

 

[meetyg]

Let's make it simple:
You build you battery pack according to the required voltage. That depends on inverter/devices that you plan on running from this battery.
Most inverters at or above 3kw, will require 48v. So first choose what voltage you want your battery to be. If it's 48v, then all 16 cells will be in series, with one 16S BMS.

If you plan on running 24v, with 16 cells, you have a few options: 1. Build two separate 8S 24v packs, each with its own BMS. Then you can parallel them. 2. Build one 24v 8S2P pack, with just one BMS (total 16 cells, every two cells in parallel and then each pair in series).

Whether you choose 48v or 24v in either configuration, you could always add another active balancer if you wish, I parallel with the BMS's balancing capabilities.

If you go 24v, I personally would choose 2 separate 24v packs in parallel. That means less load on each BMS and gives you redundancy in case you need to do maintenance on one battery or if one BMS fails.

 

[Horsefly]

A couple of minor nits on @meetyg's generally good comment:

1. While I agree that 3kW and above makes a 12V system somewhat impractical, that doesn't point immediately to a 48V system. 3kW-4kW is really a sweet spot for a 24V system. On the other hand, if you are just saying that there are more available 48V inverters, then you are right. It used to be (and I assume it still is) that a 48V inverter was more expensive than a 24V inverter of the same kW capacity.
2. I think for your second option for 24V, you meant to say 2P8S, since 8S2P is what you described for the first option.

I agree that two separate 8S packs each with their own separate BMS (8S2P) would be better than 2P8S.

 

[E. Cho]

JK B2A24S20P BMS

This is what I chose to use for my 24 volt 8S 305 AHr DIY battery and it is working well in my brief time with it, though I haven't pushed it, as my loads are mostly light. I have never needed an 80 Amp load let alone 200+ amps.

8-24S - 200A Continuous - 350A Peak - 2A Active Balancing

$160.00 USD from 18650batterystore.com.

Their dervice and speed of delivery to me via UPS, in rural Canada, was excellent. (Shipped with my 8 battery cell order)

I also bought the push button On Off Switch and the small display with the On Off Switch as both were on sale. The On Off switch made the initial BMS start up simple. The small display unit isn't needed but is a nice option for quick info when at the power system. But the info besides voltage is far too tiny for me to easily read.