Thanks for the interesting info.

My Sintra is the twin motor, twin prop version powered by two battery packs. I must confess I hadnt looked that closely at the innards as I bought this as a ready to run.

My other boat an Interceptor runs a 15v ESC controller, ok there isnt room for two battery packs, but in theory then I could connect two 7.2v batteries up with this controller.

If the Sintra does not have the ESC controller (Ive got a gut feeling that the dealer said there was in this model), would it be best to get a 15v ESC, or would it be better to get a higher rated one - if so which should I go for, what are the implications for having a higher rated ESC controller than is necessary, again does it affect run times.

There is a reasoning behind this, in that I borrowed a Futaba battery checker yesterday to check my collection of NiCad and Nimh batteries. Most showed charging levels pretty much in line with what I expected, dependent on when last used / charged and all came in between 90% and 100% charged up.

What was more strange but Im told is not unusual, is that the battery voltages ranged from 7.1v on one of the Nicads, up to as high as 8.7v on 2 of the 3000 mAh Nimh batteries I have.

On this basis therefore if the 2 batteries which read 8.7v were installed together that gives 17.4v combined - presumably this would have implications for the ESC controller rated at 15v, or is that level of tolerance acceptable.

Thanks again
Andrew