unfortunately I had no spare time to do some tests (even with the current consumption measurement).
But I received my batteries and I'll receive soon the battery charge regulator chip.
Then I have to build the test circuit on breadboard and, if it works, I'll update a bit of things.
Actually I don't think to have the current for motors passing in the regulator.
The basic idea (under test) is that theter current is naturally limited by the cable resistance (the more the current, the lower the voltage at the tether end), and so, when the current request increases, the batteries will do the job.
The DC DC regulator is used only to mantain 10-12V over the BB, cape and so on. Since the current absorbed by the "ROV-brain" is not constant, I have a floating voltage, and that's no good at all.
- DC DC regulator will mantain a constant voltage at the BB, cape and battery charger, with a max current rating of 1A (really requested is around 0,7A);
- Battery charge regulator mantains batteries fully charged without damaging them;
- when requested current is over 1A (and so, tether voltage goes down), batteries will supply the extra current.
Hope this helps and I hope it is not confusing (I'm writing fast, as I have to rush)!! :)
Obviously any advice is welcome!