Speedstar ESC and BEC - motor whine capacitor?

[Lord Warden]

Getting to grips with my new aquisition of Jeannie Deans I have now tested the battery and control mechanisms. Apart from everything running backwards at first (reversed the motor connections) she runs well but with a distinct electonic whine from the motor. Radio control setup is a Planet T5 2.4Ghz transmitter, feeding a micro size 6 channel receiver. Battery elimination and speed control is via a Speedstar 200s unit (which I cannot trace on the web) - battery is a sealed lead acid 12v unit rated at 7amp/h, and the motor is a whopping Delco 9 pole unit the size of a small Coke can, driving the common paddle shaft by means of a toothed belt. At full tilt I reckon she would destroy the paddles or you could go 1/48th scale waterski-ing, so a bit of care on the throttle is needed.

Questions!  Do you reckon that I might do better with a 6v battery? This would make the lights very dim as they are 12v, but apart from that what would be the effect? Secondly does anyone have any experience of the Speedstar 200s, and could possibly point me in the direction of a manual? And lastly, one reference that I have found to ESCs recommends to install Motor Noise reducing capacitor(s) - would this solve the constant motor whine and if so, what value capacitor(s) do I need and where should it (they) be located?

Many thanks for any help given.

[chipmonk]

Hi there, i have a couple of suggestions for you. The wine from the motor is probably due to the way the speed controller controls the motor speed. Power is fed to the motor in tiny pulses, the ratio between the motor on and off pulses is altered to feed the motor more power as you advance the throttle. Eventually almost full power from the battery goes to the motor.
 The capacitors are used to controll radio interference and will have little effect on the sound. These are connected across the motor terminals and should be 0.1uf, with another connected between each of  the terminals and the motors metal casing. These should be 0.47uf. Non polarised ceramic types with a voltage of at least 24v should suffice.
 If at 12v the drive is so powerfull as to pose a risk to the paddles then you seriously need to lower the voltage. How about two smaller batteries, one for drive and one for the lights, also lowering the drive voltage will also lower the current consumed by the battery. Try it on 6v and see.
Sorry to be so long winded but I hope it helps.
Cheers Chipmonk.

[Lord Warden]

Many thanks for that. If I try a 6v battery (and I have one to hand as it happens) will this have any effect on the speedcontroller/BEC which currently feeds the appropriate voltage to the receiver?  Not being an expert on this subject I don't want to try going down an avenue only to find that I can't return if it doesn't work!  I did think of putting a resistor in the live feed to the motor to reduce the voltage, but it doesn't sound as if this is a very good idea?  Thanks for your help.

[chipmonk]

Hi there, lowering the supply should cause no problems to the output from the speed controller to the receiver, however going as low as 6v will not give you a lot of headroom. To explain, headroom is the term given to the difference of the voltage being supplied to the speed controller by the battery and the voltage fed to the receiver usually 5v. I personally always use a separate receiver battery when operating at 6v.
And remember this type of mod is reversible.
Cheers Chipmonk.