Hi Everyone,
Another question on paralleling several packs (each with their own BMS).
There's been some threads on this topic (which I all read), and the general consensus seems to be that it is ok to parallel packs.
Doing so increases the maximum allowed current of the system, so e.g. 3 packs of 100A in parallel creates 1 pack which can do 300A (best to have some safety margin in this case, so say 250A or so max).
Now I saw this new 13-20S 200A Jiabaida BMS (relay based) which seems quite cool, but in the listing on alibaba, it says:
"Parallel use of battery packs is not supported (battery packs are directly connected in parallel, and there is a problem of large current discharge of high-voltage battery packs to low-voltage battery packs)"
Now this stroke me as odd, they probably mean that you can't connect packs together when they are at a different SoC, right?
Well, no. I asked Fidelia of Jiabaida, and she replied that connecting two packs with this BMS in parallel is not possible at all, because:
"High series number bms does not support parallel connection. The voltage of a high number of strings is very high, and the current increases after paralleling, and the chip and MOS tube will burn out. The currents of the two branches will merge together eventually"
And this goes not just for this BMS, but also for their mosfet based BMS's. She tells me that it is ok to connect low voltage packs in parallel (such as 3x 100A 4S bms, that will yield you a nice 300A 12V pack), but for high series it ain't possible due to the "MOS tube buring out".
Now I'm not a complete idiot on this topic, but the reasoning behind this is beyond me. I can't seem to understand why connecting several of these BMS's in parallel should cause any issue, especially when it's no issue for lower voltage packs. Also, I've contacted several other BMS manufacturers, and none of them confirm this issue, they all say it's no problem for their BMS.
Is there anybody who can clarify this?
Another question on paralleling several packs (each with their own BMS).
There's been some threads on this topic (which I all read), and the general consensus seems to be that it is ok to parallel packs.
Doing so increases the maximum allowed current of the system, so e.g. 3 packs of 100A in parallel creates 1 pack which can do 300A (best to have some safety margin in this case, so say 250A or so max).
Now I saw this new 13-20S 200A Jiabaida BMS (relay based) which seems quite cool, but in the listing on alibaba, it says:
"Parallel use of battery packs is not supported (battery packs are directly connected in parallel, and there is a problem of large current discharge of high-voltage battery packs to low-voltage battery packs)"
Now this stroke me as odd, they probably mean that you can't connect packs together when they are at a different SoC, right?
Well, no. I asked Fidelia of Jiabaida, and she replied that connecting two packs with this BMS in parallel is not possible at all, because:
"High series number bms does not support parallel connection. The voltage of a high number of strings is very high, and the current increases after paralleling, and the chip and MOS tube will burn out. The currents of the two branches will merge together eventually"
And this goes not just for this BMS, but also for their mosfet based BMS's. She tells me that it is ok to connect low voltage packs in parallel (such as 3x 100A 4S bms, that will yield you a nice 300A 12V pack), but for high series it ain't possible due to the "MOS tube buring out".
Now I'm not a complete idiot on this topic, but the reasoning behind this is beyond me. I can't seem to understand why connecting several of these BMS's in parallel should cause any issue, especially when it's no issue for lower voltage packs. Also, I've contacted several other BMS manufacturers, and none of them confirm this issue, they all say it's no problem for their BMS.
Is there anybody who can clarify this?