# Motor RPM limiting, Netgain/ADC with Zilla



## klickrr (Apr 11, 2008)

Hello,

I'm looking for information regarding the RPM limiter inside the Cafe Electric Zilla 1K and in combination with a ADC 9" or Netgain type motor. Now i've read that the ADC has the RPM thing which can be connected to the controller and then obviously limit the RPM. I'm wondering if anyone has experience with this and to it's effectiveness. Also any other controller/motor combinations that have worked would also be welcome information.

I have an interest in converting a waverunner to electric, so i'm looking into some things.. Obviously if the waverunner jumps out of the water, and i'm flooring it, it's going to rev up real fast, and if there's not a computer/microcontroller to stop it, the motor will "grenade" as i've read. 

Are there any large motors like the ADC/Netgain 9" which dont' have the grenading issue? Most small electric motors don't have this problem, at least that ones i deal with, and they are pretty small, so no real comparison i guess.

I've also looked at the new Mars Brusheless motor, which is the Etek replacement (or so i've read). Granted it's power is no where near that of an ADC 9", I'm not sure if it has a grenading issue or not, also i'm not sure i want to get into wiring up 4 of these to get the power i want, i'd rather use a single motor.

Anyway, just hoping to get other people's advise on this, as I have absolutly no EV experience at all.

Thanks,
Ross


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## judebert (Apr 16, 2008)

I destroyed my ADC 9" by over revving it. I'm still looking for a rev limiter; I've already got the stuff required to reattach the tach. (Of course, you won't have time to react to the tachometer: when it jumps, it'll start spinning up in way less than your 0.5s reaction time.)

If you find a rev limiter you can use, let me know.

Meanwhile, the 8" motors can rev higher than the 9", and the 6.5" can rev higher still. AC motors can also reach high RPMs without blowing apart.


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## klickrr (Apr 11, 2008)

judebert,

Well that's interesting to hear, sorry you blew out your ADC9". How damaging was it when that occured? did it physically tear itself apart? I'm just wondering how much protection i'm going to need in case it happens, regardless of a rev limiter, it sounds like i'll need significant protection if everything goes wrong with it.

As far as I know, and can tell from the specifications documents, the rev limiter on the zilla 1k (or others) reacts quite quickly, but most applications have load on their motors no matter what, i'm going to go from full load to no load (well almost) if the waverunner jumps out of the water. The ADC 9" has the built in rpm guage, meaning there supposedly is a wire that comes up that basically is hooked to an optical sensor and a disc that flickers as it rotates, in very simple terms. 

Hoping to hear someone who has an adc 8 or 9 with a rev limiter and knows that you can just floor it and not worry, that would be nice.

Ross


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## judebert (Apr 16, 2008)

klickrr said:


> judebert,
> 
> Well that's interesting to hear, sorry you blew out your ADC9". How damaging was it when that occured? did it physically tear itself apart? I'm just wondering how much protection i'm going to need in case it happens, regardless of a rev limiter, it sounds like i'll need significant protection if everything goes wrong with it.


Yeah, it was pretty devastating. Basically completely destroyed the armature and scraped up the field coils, too. 

You may be better off using motors that can handle high RPMs. I don't know how you can possibly protect a motor against the kind of load swings you're expecting.



klickrr said:


> As far as I know, and can tell from the specifications documents, the rev limiter on the zilla 1k (or others) reacts quite quickly, but most applications have load on their motors no matter what, i'm going to go from full load to no load (well almost) if the waverunner jumps out of the water.
> 
> Hoping to hear someone who has an adc 8 or 9 with a rev limiter and knows that you can just floor it and not worry, that would be nice.


I'd call Omar and ask. At the very least, he should be able to tell you how quickly he'll shut the power off, and whether he's doing some sort of extrapolation or if he just determines from two pulses that the motor is now going too fast.


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## ngrimm (Oct 19, 2007)

I read somewhere that some motors have a small kevlar band around the commutator to help it survive higher rpms. Do think that would be enough insurance? Norm


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## Hi Torque Electric (Dec 23, 2007)

Hey Grimm

In fact I rebuilt Judes armature and wrapped the commutator with 3 Kevlar bandings. He's got pics up as his site and his motors also albumed at mine as well. I've done just a few of these looking for info on how it'll do before "flooding" them as it's a bit new and untested per se. Not sure how much stronger it'll actually make them but sure can't hurt 8^) Anyway, have a look.
Jim Husted
Hi-Torque Electric


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