Electronic speed contollers - few questions

[Daz82]

I'm confused by the terms they sell them

Whats all this turn limit malarky? I was trying to be clever and work it out myself but its actually stumped me a bit!

And what does the No Limit mean on some of them?

 

I'm just looking for a good quality middle of the road contoller that I can still use when I've continued upgrading whatever I end up getting!

 

[modelmaniac]

Hi mate, i was stumped when i first got into rc so dont worry!

Basically, the "turns" refer to how many times the copper wire is wound around the inside of the motor.

More "turns" or "winds" = faster motor, though you may need to adjust your gearing ratio to achieve the best results, and also to help prevent damaging your motor/esc.

Depending what motor you wish to run, consider that your esc MUST be up to the job. For example, if you wish to run a 21 turn motor, your esc must have a turn limit of 20 turns minimum. I try and always keep a couple of turns gap, just in case.

If you choose a "NO LIMIT" esc, you can fit any motor you wish, though you may still need to adjust your gearing.

Depending on your budget, there are a badword of alot of esc's out there, i always use either the kit esc (good for any 27 turn motor, though some people have used slightly faster ones with no problem) or anything by NOSRAM or MSONIK.

MSONIK are very good, quick to set up and are waterproof.

NOSRAM, again are very good esc's and there are several to choose from, depending what motor you wish to use. Though if you choose a good NO LIMIT, or even a low limit, you dont have to worry about upgrading in the future.

Hope this helps.

Cheers

Modelmaniac[6]

 

 

[Gruntfuggly]

ESCs are rated by the minimum number of turns (in the motor) that they can drive. The lower the number of turns, the more powerful the motor (in general) so an ESC that can handle 27 turns will only really be able to drive a stock motor. No limit simply means that the ESC can be used with any motor...

Nuts...[]

[rhenbelz]

Turn limits are more of a guideline, some motors are harder on ESCs than others. Also you can blow up ESCs and batteries if your gearing is wrong even if you're well within turn limits. Likewise, if you have your drivetrain geared properly or for torque, you can often safely go under turn limits. A freely revving motor is much easier on an ESC than one struggling to move. Turn limits are more about how soon the ESC starts overheating. Most quality ESCs can handle quite a bit of abuse.

Old forward-only racing ESCs like old Novaks and Tekins can handle lots of cells and in theory have no motor limit, but often they use wiring that's unsuitable such as 14 or 16 gauge. They'll overheat too... they're really made for mod stock motors. Newer forward-only ESCs are great for whatever, and they have the added benefit of being more efficient than reversing ones. Many are programmable too and have posts for soldering new leads on. Duratrax sells an 8-turn forward-only racing ESC that I've found to be very reliable and has extensive programming options.

ESCs with lower turn limits are often more efficient and have better power flow, with lower on-resistance and better wiring. In my opinion, if you want to run low turn motors, it's often cheaper to jumper an EVX or similar 14.4v ESC for 7.2v use instead of buying an expensive and often non-reversible no limit ESC.

 Don't automatically assume that to make your car more fun you must get a low-turn motor... you can have just as much fun with a mod stock motor by changing gearing to turn the extra torque into higher speed. Then you also get a longer battery life.

 Last thing to note is if you are running low turn motors and/or agressive gearing, make sure your batteries are up to the task. Too high a draw can have bad effects.

[Daz82]

Excellent information there thanks guys, Think i'm finally getting my head round this now!

How exactly do you alter the gearing?

 

Must admit I havn't looked ino this bit yet but worth asking you lot as all the garbage is translated into english!

 

[Nitro_John]

How exactly do you alter the gearing?

 You alter the gearing by changing the pinion and/or spur gears in the cars transmission.

Your cars manual (Tamiya) will have a little chart at the back showing combinations of the pinion and spur gears and the gear ratio. Ie. a 7.0 gear ratio will make your car accelerate really quickly but have a low top speed where a ratio of 5.0 will do the opposite. You match the gearing to the track and motor, so the motor can spin nicely without getting too hot and damaging your speed controller.

[rhenbelz]

Agreed, just thought I might point out that if you don't have the chart to reference, more teeth equals higher speed and less torque (requiring more torque from motor) and less teeth goes the other way. Most Tamiyas are geared somewhat conservatively so a stock pinion will do fine for mild motor upgrades like a Sport Tuned but ideally on other motors you want to match the changes in motor RPMs with a change in pinion. Otherwise, twice the RPM may mean twice the top speed but the extra torque required from the less torquey motor can damage electronics and the motor.

[Daz82]

Ahh I see - have only really glossed over the manual upto now - looks like an in depth read over the weekend!

[Daz82]

Quick update - My Clio Williams manual doesn't seem to have any info on ratios?

[MikeG8]

There is useful info on Time Tunnel's site about turns and motors.  I think it is on either the motors page or the ESC's page of the spares bit.

Mike