So, can it be summarised that 2 brushless motors/2 esc's can be used with 1 battery BUT it is preferable that opto esc's are used along with ferrite ring to reduce interference.
Opto means that a second power source is required for the Rx which adds to the weight so you might as well use 2 batteries.
If weight is critical then you're lumbered?
Or have I misread the situation totally?
Tony
You can use two escs with one battery. Just don't hook up the second esc with alligator clips or only the positive wire when you find it works perfectly on the bench. That is the two most memorable instances where I was asked to do repairs.
If you get mysterious signal problems where one throttle affects the other then the obvious first step is to wrap one lead round said ferrite OR look up the internet on how to opto-isolate one of the escs. The purpose of opto isolation is to break the ground loop, the wound ferrite is to impede differential current that could circulate via a ground loop. Both measures would be redundant. Two opto escs would also be redundant and would require you to install an additional bec. I wouldn't waste time looking for a marine opto esc.
So if you have a high permeability ferrite then wrap one of the 3-way cables through it.