How Forgiving are built in BMS's?

[offgriddle]

When mixing different brands of 12 volt, Lithium iRon Phosphate batteries containing built in, non used programmable BMS's, is there a compatibility issue amongst the different BMS's when the batteries are connected together?

 

[HRTKD]

Series or parallel connections? I would be reluctant to series connect different brands. Some do not approve of series connections, some do.

If it's parallel, I don't think it would matter too much, but the Ah capacity and age of the batteries may be more of an issue than the BMS.

 

[offgriddle]

Series or parallel connections? I would be reluctant to series connect different brands. Some do not approve of series connections, some do.

If it's parallel, I don't think it would matter too much, but the Ah capacity and age of the batteries may be more of an issue than the BMS.

Yes fer sure, series connection is a horse of a different color, I intend only to connect the mixed batteries in series for this application. Two existing batteries are 20 Ah and the third, new battery would be a 30 Ah.