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Parallel connection of two BMS for one battery.

cobrasb

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Wondering if it is possible to connect two identical BMS in parallel to one battery to handle higher current rate in case one BMS is not suitable(or not enough) to handle the amount of current requested by the system. Did someone tried this? How the cell ballancing will work when two BMS will try to ballance one cell?
 
Hello.
That is my idea. :D
I have 2 bms in backorder to try that, well I thought to do that with just balance boards witch can balance only 1.2 amp per cell, it would double the current, maybe. If your bms is top balancing, it could save you when one battery goes up much faster than the others, it will consume double the current, I guest.
 
I would rather wonder if for example one BMS is able to handle 100A. So after connecting the second, but the same spec. BMS in parallel wih the fisrt one(but to the same cells as the first one). Will the whole system be able to pull out 200A from the battery without getting disconnected from the battery because of high current BMS protection?
 
even with different specs it should work.
If you set one to top balancing at 4V, and the other at 4.2V, maybe the resistors would burn on the 4.0V before the 4.2 gets a chance to work, the same with low cutoff, depending on the current.
 
Wondering if it is possible to connect two identical BMS in parallel to one battery to handle higher current rate in case one BMS is not suitable(or not enough) to handle the amount of current requested by the system. Did someone tried this? How the cell ballancing will work when two BMS will try to ballance one cell?
hello I found that video, he talks about 2bmss at the end.
 
Vous vous demandez s'il est possible de connecter deux BMS identiques en parallèle à une batterie pour gérer un taux de courant plus élevé au cas où un BMS ne serait pas adapté (ou pas assez) pour gérer la quantité de courant demandée par le système. Quelqu'un a-t-il essayé cela? Comment le ballancing de cellule fonctionnera-t-il lorsque deux BMS essaieront de balancer une cellule?
Avez-vous vu cette vidéo
Et avez-vous essayé 2 bms untile your last post?
 
I'm hoping to do this with two overkill BMS, but there doesn't seem to be a lot of actual real-world examples of people doing this which is giving me some concern.
 
I'm hoping to do this with two overkill BMS, but there doesn't seem to be a lot of actual real-world examples of people doing this which is giving me some concern.
Great news about the Overkill BMS in parallel.... It works GREAT! Though not recommended by Steve at Overkill, and a mess of wires... I'm assembling and testing it out. Zero issues pulling up to 180 amps from one set of 4s 280 amp hour cells! I can only charge at about 20 amps do to charger limitations for now. I'm going to start a new thread about it too... Sorry for the mess of wires, it'll get cleaned up for install, LOL!
 

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Did you keep that system running?
And if so, how stable was it -i.e. did the cells stay in control, and did you have any heat issues over time?
I am currently running two 4s strings paralleled to get extended duration but considering attaching them as you are to increase capacity so that I can run a small AC.
 
Did you keep that system running?
And if so, how stable was it -i.e. did the cells stay in control, and did you have any heat issues over time?
I am currently running two 4s strings paralleled to get extended duration but considering attaching them as you are to increase capacity so that I can run a small AC.
So I've used this setup for almost two years?
Give or take a bit...
No issues with the BMS or cells going out of balance. They split the workload evenly, both charging and discharging....
No issues at all!
I thought I'd separate the BMS for two packs, but never got more cells thanks to a debacle with cells awhile back. ?
Still running one pack with 280 amp hours.
 
Most situation won’t push the BMS close to their limits but if you’re using two BMS on one battery and push them to the limits. I can think of several ways that Parallel BMS for one battery “might" cause problems. Let’s say you have a 100 Amp charger and a 100 Amp load but each BMS can only handle 50 Amps Charge and 50 Amps draw. If you drain a battery down to it’s BMS cut-off voltage. One BMS will cut off to protect the cells before the other so it will get the full 100 Amps and likely “overload" Trip the other BMS.
Same with the charging after a low voltage cut-off. If the charger is pushing 100 Amps one BMS can kick in first and as the threshold voltage won’t be exactly the same on each inverter as if they were triggered by the same circuit. The one 50 Amp BMS will be dealing with the full 100 Amps and could cut out. In some rare conditions you could possibly get a Current Limit Protection ping pong effect bouncing back and forth on each BMS.
 
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