Capacitors and Diodes for 8.6 V BB Speed 700 Motors?

[RvE]

I am building a 12 cell, Electro-Vee and using a 8.6v BB Speed 700 motor with the Astro 212D ESC. Are capacitors across the motor terminals required or recommended with this set up? I believe that some folks do not use them, but I was interested to see what most people are doing on this topic. Is it prudent to install the schottky diode across the terminals as well?
If capacitors are recommended, what size and where are they installed? I am a little concerned about soldering the one capacitor terminal to the motor housing since I think it might be tough to ge the housing hot enough for a good solder connection. Any tips on how to do this?
I know that this is common practice on 05 motors but my questions specifically relate to speed 700 motors.

Thanks for your help RvE

[AndyKunz]

Caps are recommended for noise suppression.

All my Astro's have had a small solderable tab bolted to the can near the endbell - you won't be soldering to the aluminum can very well.

The diode is recommended to prevent blowing your ESC's FETs. Wire it directly across the brush hoods - on mine, it has actually served to keep the stuff together after melting the hood out of the hole!

Andy

[Ernie Lazenby]

On BB Turbos I always use 3 x ceramic capacitors and a Shotky diode. I never get glitching problems so I think the method is ok.

I use a .1 uf capacitor from each terminal to a central point on the can. A .47 uf capacitor goes across the two terminals with the diode.

[Jeff Wohlt]

Ernie, do you have any part numbers or do I just go to radio shack and ask for those specs?

[Steven Vaccaro]

Any need to run a capacitor with a r/c hydros esc? I havent been.
StevenV

[Andrewg]

I also run a metal oxide varistor rated at 3-5v over the charged pack capacity to help part throttle warming of the esc. I have found this also help with glitching on big current hi cell count motors.

Supression will support the proper operation of a controller and more especially the reciever.

Marconi transmitted across the Atlantic using a spark!

[Allan]

Many motors now are sold as ready suppressed - e.g. the 700 turbo 12v. Others have no suppression fitted - e.g. the 700 turbo's. Most motors have insufficient suppression for high frequency ESC's. (i.e. 1+ khz).

The idea of suppression is to soak up the spikes - this is best done as close to source as possible. You also need to keep the spikes manageable - i.e. within the capabilities of the Schottky diodes. The problem exhibits itself at part throttle and is worse with higher frequency ESC's.

Suppression is a requirement not an option.

Allan

[Ernie Lazenby]

Jeff. I get my capacitors from Allan at Astec but you should be able to get them easily from Radio Shack.

Ernie.

[Ernie Lazenby]

I forgot to mention that my article in the March issue of MMI(Published Feb) contains a piece about how to suppres motors.
Its a guide for Mr average, I know most of the experts know how to do it but the thrust of my articles will be directed towards those who dont know what they are doing or those like me who want to learn a bit more. My live wire feature in future will be a bit of a mixed bag looking at F/E issues of course but also looking at fast scale boats etc.
The article also contains info about Shultze speed controllers for Brushed motors and info about some rocket scientists- yes real rocket scientists!! (If you cannot wait read the info on the Darlington & District Model Boat club site.)

Cheers. Ernie

[RvE]

Thanks to all for the good info. I am going to install the capacitors as described by Ernie. I took a look at my 8.4 V BB 700 motor (Cordite brand supplied by Fine Design) and I am still not sure where and how to solder the capacitor to the can. Sorry, I am a bit slow on this. The solder connections across the terminals are simple but I do not see an easy spot to make a connection on the can. I have a cooling coil around the brush end of the motor so the side of the can is covered by the coil. Do people make the solder connection to the edge of the can or is there another good spot. The can looks like it will take a solder connection while the end bell appear to be aluminum (perhaps - I am no expert on this) which may not take a solder connection.

Anyone got any photos of a Speed 700 with cooling coil showing how they install these capacitors?

Thanks in advance for your help. RvE.

[AndyKunz]

Originally posted by Pagemaster
Any need to run a capacitor with a r/c hydros esc? I havent been.
StevenV

Neither have I for years. I still have some older motors with them, but I don't build them that way any more.

Andy

[AndyKunz]

Originally posted by Andrewg
Andy supresison will supporthe proper operation of a controller and more especially the reciever.


Andrew,

CanIhavesomeofthosedrugsyouwereusingwhenyoutypedth at? ;)

What were you saying?

Andy

[Ernie Lazenby]

Rve
Looking at the back of the motor, mark the outside circumference of the can mid way between the terminals. Use a file to roughen up a small spot on the can then solder the capacitor legs to the can. I use a 75 watt iron. You may have to move the cooling coil to create space.

Ernie.

[RvE]

Ernie
Thanks for the detailed info. I will install the capaictors as you described.

RvE

[Andrewg]

Andy

sfixed!

I think I was going to say - Andy...... (something BEC's or similar).

However I decided against it and changed everything but Andy - apologies for implicating you!