Very good idea to have two sets of batteries and changeover circuit,but then you need to have exstra enclosure and the Payload Skid.(the BlueROV2 will be much higher and heavy,i like the height and weight as it is now)
What output voltage,should be to charged the battery?
Isolated DC/DC converter I’ve found has only 60W (4Amp) i can use three of them (12Amp)
These Isolated DC/DC converter is very expensive,but best quality.
Isolated DC/DC converter can not be bigger,it is very small place in the battery Enclosure,but it is enough space for 3-4 60W.
Can you trust on this BMS printed circuit board? was very cheap.
Does this have any impact on the QGroundControl or software to Bluerov2? (Voltage measurement,Amp measurement,Safety settings)