100a JBD 4s BMS in a 24V system

neil_99

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Hello. This is my first post, so please be gentle. Also, I'm not sure which section of the forum this question fits best, so I put it here since I think it's really a BMS question. I have purchased 16 - 304a Eve cells from Amy. I also purchased 4-JBD 100A BMS from her at the same time, and hopefully, all of this will arrive in a month or so. I've gone back and forth on whether I wanted to build a 12v or 24v system. When I ordered, I was planning on 12v, but now I'm planning on 24v. From reading in the library, it looks like I can just make 12v packs (using the 4s BMS) and connect them in series to get 24v. I believe this would give me two 24V 304ah batteries with a maximum discharge rate of 200 amps (100amps for each 24v pack). Is all of this correct?

If all of that is correct, I think I have a problem with my proposed inverter. I'm planning on getting a Multiplus 3000/24, and the manual calls for a peak power of 6000 watts and a recommended fuse of 300amps. I wonder if the 6000 watts is related to power assist, and not the actual draw on the battery? Since the wattage of the inverter is only supposed to be 3000 watts, I wonder if these BMSs will be sufficient (3000/24=125amps divided over two 100amp packs)? Or, do I need to find another BMS and sell what I have ordered? Thanks!
 

Bob B

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Your conclusions are all correct in your first paragraph ..... as far as supporting the MultiPlus, I think you will be fine.
 

pierre

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I would go for the highest voltage battery practicable. In your case 16 x cells in series with one 16s BMS and a 3- 5kVa inverter. I am always dubious about putting BMSs in series without active comms between them. Paralleling of BMSs is quite acceptable in my opinion.
If you want to stick to 24v , build an 8s2p combination but you then need 2 x 8s BMSs.
 

RV10flyer

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My work van setup. 5X200 or 1000W Solar, Series Connected, Midnite 250 SCC, 4K 120V Magnum Inv, Two Daly 8S 250A BMS, 16 ea 304-316 aH cells, two parallel batteries, balanced and matched as close as possible.
 

neil_99

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Jul 18, 2021
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Spring, Tx
I would go for the highest voltage battery practicable. In your case 16 x cells in series with one 16s BMS and a 3- 5kVa inverter. I am always dubious about putting BMSs in series without active comms between them. Paralleling of BMSs is quite acceptable in my opinion.
If you want to stick to 24v , build an 8s2p combination but you then need 2 x 8s BMSs.
I don't want 48v because that makes some of the parts much more difficult. Can you explain what the concern is with two BMS in series without comms?
 

pierre

Somewhere down South
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Dec 21, 2019
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I don't want 48v because that makes some of the parts much more difficult. Can you explain what the concern is with two BMS in series without comms?
The problem is that the series current will be determined by the weakest BMS and its associated battery. Further , if one BMS dies the battery is dead. With them in parallel you only lose 1 string and the load stays connected ( depending on load current ) . I have never used BMSs in series and I stand corrected by those who have.
 
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Just John

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Aug 15, 2020
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Hello. This is my first post, so please be gentle. Also, I'm not sure which section of the forum this question fits best, so I put it here since I think it's really a BMS question. I have purchased 16 - 304a Eve cells from Amy. I also purchased 4-JBD 100A BMS from her at the same time, and hopefully, all of this will arrive in a month or so. I've gone back and forth on whether I wanted to build a 12v or 24v system. When I ordered, I was planning on 12v, but now I'm planning on 24v. From reading in the library, it looks like I can just make 12v packs (using the 4s BMS) and connect them in series to get 24v. I believe this would give me two 24V 304ah batteries with a maximum discharge rate of 200 amps (100amps for each 24v pack). Is all of this correct?

If all of that is correct, I think I have a problem with my proposed inverter. I'm planning on getting a Multiplus 3000/24, and the manual calls for a peak power of 6000 watts and a recommended fuse of 300amps. I wonder if the 6000 watts is related to power assist, and not the actual draw on the battery? Since the wattage of the inverter is only supposed to be 3000 watts, I wonder if these BMSs will be sufficient (3000/24=125amps divided over two 100amp packs)? Or, do I need to find another BMS and sell what I have ordered? Thanks!
You are correct, that will work. I would attempt to order a couple of 24v BMS instead, you will be happier in the long run. When placed in series packs can get out of balance, although with matched cells that isn't likely. JBD does make some excellent 150 amp and 200 amp rated BMS for 12v packs, but only 150 amp for 24v maximum (that I've found). 150 amps at 24v would handle a 3000 watt mulitplus. If you have two in parallel, it will work very well.
 
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