how do you know what size esc to run ??

[abmarine]

Hi Guys,
New to electrics and still learning, Need to know what size ESC to run on a leopard 3665 ( 2100 KV ) brushless motor ?? i got a Turnigy 120 marine ESC but thinking a 90 ESC may be enough ???

Thanks in advance.

Tony

[jcald2000]

I would consider the 120 bare minium. 180 or 200 is best.

[jamespl]

It's always best to go a bit overkill with the amp rating cos if you under rate it the esc won't last long so long term the higher rater the esc the better IMO.

[martin]

Agree 120a min & dont go to big on prop size & check temps.

[jonjon00]

Maximum amp rating of motor plus 25% will get you a good number for your speed control amp rating every time.

[siberianhusky]

Combination of a number of things, none of which are scientific!
Size and type of hull, watt rating of the motor and the voltage you intend to run, experience and copying what has worked for other people.
The watt rating of the motor is just a vague hint of what may happen as an electric motor will draw current until something blow up.
As suggested above you are better off going bigger.
Personally wouldn't hesitate to run that motor on a 120 esc, shouldn't be a problem at all if an appropriate prop is used, quite often run a Castle 1512 in a Motley Crew with a Swordfish 120 esc. Bigger motor than the Leopard but the esc and motor run cool. Could easily run more prop than I usually do but I'd rather have the longer runtimes, still much faster than the stock motor.

[larryrose11]

Im a noob too, this is my 3rd season in. I found that the prop is ultimately determines what the current draw wil be. This is because it requires more torque to turn a larger prop diameter or pitch of a prop. More torque requires more current. The esc's typically used in RC dont really have a controlled current limit, so overkill is good. It is WAY better to get speed from a boat by increasing the battery voltage and use a small prop than the other way around of increasing prop pitch and size. This will help keep the current in check, which will help keep the tem in check, assuming the water cooling is working.

[abmarine]

Awesome, Thanks Guys Much appreaciated, Use ful information there.

Tony