how many BMS's
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MisterSandals
Participation Medalist
If you'd like to use a single 4S BMS, you could configure your 8 cells as a single 12v battery.
Excellent idea. Thank you very much, and thanks for the picture as well!
@MisterSandals Thanks for the picture. I am NEW at this and trying to wrap my head around all I am learning. Yours is making 8 cells into 1 12V 200AH battery, correct? It looks like you put them in 4 parallel pairs first, then put the four parallel pairs in 4 Series. How is that different than this diagram from Will that is a 24V system?
From your picture it looks similar, but Will's has two bus bars on each series. Am I seeing the right? Your label on the image is 4S2P, but you still put them in Parallel pairs first then in series, correct?
I am trying to learn enough to buy two of these:
LiFePO4 12 200Ah Batteries
and make a 24v 200AH battery. How would I do that with a minimal number of BMSs?
From your picture it looks similar, but Will's has two bus bars on each series. Am I seeing the right? Your label on the image is 4S2P, but you still put them in Parallel pairs first then in series, correct?
I am trying to learn enough to buy two of these:
LiFePO4 12 200Ah Batteries
and make a 24v 200AH battery. How would I do that with a minimal number of BMSs?
FilterGuy
Solar Engineering Consultant - EG4 and Consumers
Will and Mr Sandles have the same electrical arrangement with a different physical arrangement.
MisterSandals
Participation Medalist
That diagram will also produce a 12v battery (appears mislabeled).
More connecting material = more better.
8 cells in series. One 8s BMS is all you need.
MisterSandals
Participation Medalist
Do note that they can all be in a row and not necessarily in a cube (square?) as pictured.
FilterGuy
Solar Engineering Consultant - EG4 and Consumers
It looks like the image came from this page:
https://www.mobile-solarpower.com/design-your-own-12v-lifepo4-system.html
On that page will is talking about 12V systems.
https://www.mobile-solarpower.com/design-your-own-12v-lifepo4-system.html
On that page will is talking about 12V systems.
MisterSandals
Participation Medalist
Also on that page, with images and descriptions entangled, are mentions of 24v and 48v BMS systems... (attached is what the OP should use from that page)
FilterGuy
Solar Engineering Consultant - EG4 and Consumers
I thought the OP was building for 12V...??? In the first post he said: "I am building two 4 cell 12v 100aH batteries which i plan to then put in parallel for a total of 12v 200aH"
FilterGuy
Solar Engineering Consultant - EG4 and Consumers
Do you have a particular BMS in mind? I have a hard time finding a 200A 12V BMS that I like and is affordable.
MisterSandals
Participation Medalist
FilterGuy
Solar Engineering Consultant - EG4 and Consumers
Got it..... we were going back and forth on voltage and I lost track.
Thanks
FilterGuy
Solar Engineering Consultant - EG4 and Consumers
OK.... , the best way to make a 200AH 24 Volt battery it is to start with 200AH cells and arrange them like this:
In the original post, 100Ah cells were mentioned. To minimize the number of BMSs on a 24V bank you would wire 100Ah cells like this:
Note: This is Parallel-first and is my preferred way to do it if I am ganging up smaller cells to get higher Ah.
Other folks on the forum believe series-first is better, but it requires 2 BMSs. Using 100Ah cells, parallel-first would look like this:
- All 3 of these arrangements end up with 24V 200aH.
- In all 3 arrangements the BMS(s) are 8S BMSs,
- In the 8S2P arrangement the two BMSs can be half the current of the BMSs of the other two arrangements.
This helps a ton. That is the page I got it from. I had read from the top of the page from 12v then down through the 48v builds. I was having a hard time figuring out how the cells would get to 24v from the diagram at the bottom that I shared previous. Reading again I see that it is referring back to using smaller cells to create a larger battery to the size of a 12v.
You are correct, I think I inadvertently hijack the OP's thread. Sorry.
@FilterGuy Thank you very much! The diagrams are exactly what I needed to help me understand.
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