Observed the same warning for a 100Ah 12V Renogy battery.
I found also this online:
There is no theoretical limit to the number of batteries that can be connected in parallel. As more batteries are paralleled together, the risk of one faulty battery affecting the entire battery bank increases.
Could that be related to a certain failure threshold manufacturers do not want to cross?
Each parallel string is adding extra probability of failure: +0,01% + 0,01% + .... in total can be something.
Battery failure can originate a fire, further failure, etc...
There is no theoretical limit to the number of batteries that can be connected in parallel. As more batteries are paralleled together, the risk of one faulty battery affecting the entire battery bank increases.
The BMS would have to fail in a way as to not take the battery off-line. A cell going over or under volt would take that battery off-line. Hopefully the BMS is designed to go off-line when it fails. But, if it doesn't, then it will cause problems for all the batteries (hence the need for the class T fuse).
The more BMS's, the more likely one of them fails. It is only a real problem if you have a high failure rate (or a lot of BMS's). If 1% of BMS's fail in any given year, then you have a 1% chance of your one BMS failing. If you have 10 BMS's, then your odds are higher that one of them fails in any given year.
Kind of like the more disk drives you have, the more likely one of them will give you a problem that year. Don't know which one. At home, your drive fails when your drive fails. If you are running a server farm, drive failures are a regular occurrence.
