No i just got one of these for testing right now. And i wanted to know if i could use them that way. Just for interest. Right now thinking about building a little system for testing cells via solar with a backup battery made of the 18650s i have right now. This should be very cheap or made from things i could use later on. So im thinking of using what i got or wich things i would need for sure
Agree with daromer and mike. The bms is there to do a job. If you piece together two units, you've effectively took part of that protection away.
As mentioned earlier, if the bms units are not exactly the same values, 1 of them could shut off before the other one. This would cause for sudden issues. Spikes in voltage could be an issue, hammer effect could happen (where the units kick on/off rapidly), or the smoke could be released.
Most bms units are designed to work alone. They handle a full string (the system voltage) of the battery, not portions of it.