9C brushless motors. how far have you overvolted?

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jimmyhackers
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9C brushless motors. how far have you overvolted?

Post by jimmyhackers » Aug 05, 2015 6:45 pm

name kinda says it all. have asked this before on another forum with limited responses.

id like to get a good idea of how far people have taken their 9Cmotor in amps and volts without any cooling mods.
and also how far people have taken it with cooling mods.
and the kinda performance you go,(including reliability)

ill start...
48v1000w (20A) brushless 9c china copy motor. overvolted to 60v and still 20 amps (1200wats). i get 35mph on flat 30mph uphill 40mph downhill (all without pedalling). only electrical mod is bigger voltage caps in the controller.

i ask as "the internet" seems to says upto 2000w watts with no cooling mods needed. past 2000w air cooling is needed. past 4000w oil cooling is better/needed. problem is im not sure how those wattages translate into volts and amps.

so yeah. let me know some number guys
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Re: 9C brushless motors. how far have you overvolted?

Post by Drunkskunk » Aug 05, 2015 7:31 pm

100 volts is fine. I think a few have run them above 120v. I think they laminations reach saturation if you go much beyond 120v, though.
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Re: 9C brushless motors. how far have you overvolted?

Post by bionx 1954 » Aug 05, 2015 7:56 pm

I am running a 9C 2807 at 83V (hot) @40A with 2900 W peak. I have 7000 KM with no problems. I have drilled the side covers and upgraded the phase wires.

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Re: 9C brushless motors. how far have you overvolted?

Post by dogman dan » Aug 06, 2015 8:27 am

120v, but not for long. :twisted: It was poorly air cooled, and race conditions.

Seemed to me like saturation was closer to 100v and 40 amps. That stayed cool a lot longer.

IMO, pointless to flog one much past 3000w, unless you just dig the smell of cooked motor. Get a motor with wider magnets, and it will pull better at 2000w, than a 28mm wide motor at 3000.

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Re: 9C brushless motors. how far have you overvolted?

Post by spinningmagnets » Aug 06, 2015 8:39 am

The Pikes Peak racer used a 9C...see several posts below for the details.

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Re: 9C brushless motors. how far have you overvolted?

Post by 999zip999 » Aug 07, 2015 12:30 pm

84v at 40amps without drilled side covers will melt as soon as you add hills or sand.
2400 watts or 84v 30amp is something it can live with. A sine wave to get rid of that 9c whine. Shit my muxus 3,000 has that same whine with a em3ev 12fet 40amp at 84v. How your whine ?

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Re: 9C brushless motors. how far have you overvolted?

Post by Htfan » Aug 07, 2015 4:22 pm

Glad the OP asked this question. I'm currently at 48v 30a just fine and considering running 72v 30a+ and wondering if it requires any modifications like upgraded phase wires, venting etc.
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Re: 9C brushless motors. how far have you overvolted?

Post by wesnewell » Aug 07, 2015 4:44 pm

I've been running my 4.5 year old yecomusa 48V 1000W motor on 24s lipo (100.8V max) with a 40A controller for over 3 years without doing anything to it. Of course I don't run it full wot much. As long as you don't up the amperage much, there's no need to upgrade the phase wires. How much problem it will cause will depend on the load. I'm ~270lbs.
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Re: 9C brushless motors. how far have you overvolted?

Post by itchynackers » Aug 07, 2015 5:42 pm

spinningmagnets wrote:The Pikes Peak racer used a 9C at 111V, ventilated the side plates, and also trained for a year to get into the best possible shape so he could pedal along as much as is possible. I don't recall the amps, but I am certain it was at least 30A continuous (and likely more than that), so 100V X 30A = 3,000W minimum with occasional higher peaks. I believe at the end of the race, you could smell the baked varnish vapors flowing out the ventilation holes...(wish I could have been there).
This is almost all completely wrong. It was run at 30s (126V hot). It was liquid cooled with 600ml of synthetic tranny fluid. I trained a while, but had ACL surgery 2 months prior, so my strength was limited. Also, in retrospect, I doubt my pedaling was much help. I wish I wouldn't have pedaled at all. It was run at 22 amps max, cycle analyst limited. There wasn't any smell/leakage. It was just that my temp gauge had a wire come loose toward the top, so I had to speculate as to what the max temp was. The wire loosened at 100C, so I guessed at a peak temp of 119, but it could have been much cooler. I did run the bike at 30s and 60amps for a while after, but have since run it at 25s and 65 amps for the last few years. No problems. Hope that clears it up.

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Re: 9C brushless motors. how far have you overvolted?

Post by spinningmagnets » Aug 07, 2015 6:32 pm

I apologize, Adam. I should have looked up the article for the actual details. I was winging it from my memory. Thanks for posting the accurate info...

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Re: 9C brushless motors. how far have you overvolted?

Post by 999zip999 » Aug 08, 2015 12:19 am

Legends have a life of their own. Live with it. Lol. A Legend. E.S. style.
We don't care if you pedal you had a battery working or not.

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Re: 9C brushless motors. how far have you overvolted?

Post by jimmyhackers » Aug 08, 2015 3:22 pm

thanks everyone for the info.

seems like i can go a fair bit further with mine as it is.

luckily i only weigh 10.5 (66.6kilos). the bike with 5 lead acids weighs nearly as much as me (60kilos).

my bike will be shedding 25ish kilo and gaining some voltage making for around 72v total when i finish/add my new batteries.

if lithium does what it says on the tin.....it should be able to provide a more stable current and hopefully ill see a torque increase.

kinda a shame i wont be able to tell/feel what did what "exactly" as ill be adding more volts, "possibly"more available amps and less weight all in one go.

72v x 20amp = 1440 watts..... looks like im well under wattage wise.

thanks again everyone
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Re: 9C brushless motors. how far have you overvolted?

Post by dogman dan » Aug 09, 2015 6:07 am

At that level, 72v 20 amps, you can abuse the hell out of the bike freely, with few worries.

I used to run 72v 40 amps all winter when the motor could cool off faster, then about late spring I'd fry the halls on it. For the rest of the summer, I'd run the motor on 72v 20 amps, with no problems. The riding was dirt, going balls out as much as possible, lots of steep hills and other riding that loves to fry motors. No problem in 110F heat, riding as hard as I could, with only 1500w.

No vents, too sandy and rocky out there in the dirt to run a motor full of holes.

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