there are lots of parameters to look for. firs of all have a look on the preciseness of the charging voltage. In different temperatures. then have a look on the current ripple, especially on the end stage of charging. Life, Efficiency and etc would also have greate value to be considered...
I absolutely recommend you to consults experienced engineers and use high-tech underwater thrusters. The field you have selected for activity is really hard and I think you need to have some technical coach.
The best topology for battery cells is to parallel them first and then make them series. If your cells have electronics which can not been removed, you may have some problem such as tolerances of voltage measurements or even more leakage current. Preferably it is better to use cell with no...
The discharge rate depend in some factors. Temperature,chemistry, age, SOH & etc. when you connects the battery to a device you must be counts on the leakage of the device too. Most of the device have a considerable leakage current.
Hadoo
Head designer at www.lianinno.com