9C @ 2500+ watts

[dougnutz]

I am curious how many people out there are running a 9C at or above 2500 watts.

Also what sort of precautions have you taken, such as temp sensors, and what sort of problems have you faced?

 

[Ykick]

I see that between battery/controller with no mods on my square cover 1yr old 9C. The cover reaches 120F on hot days after running 4 miles hard on/off. Some uphill, some not, city stop & go. I baby it a little more during really hot days and sometimes drop back to 12S RC Lipo instead of usual 15S but I would be more careful and take further precautions for longer stretches and/or continuous uphill climbing.

 

[pwbset]

I am curious how many people out there are running a 9C at or above 2500 watts.

I've been curious about this myself. I'm about 4 weeks away from buying a motor for this summer and I'm trying to do a "light weight" build this time around compared to my old overkill monster 5xxx clyte bike that weighed in around 90-95lbs, but need 2.5kw or thereabouts for 15 minutes sustained to climb 1,600ft. Seems that might be a bit much for a 9c unless it's vented/cooled. Used to do it with a clyte 4011 @ 2kw, but that was really pushing it. Also looking at Magic Pie III and MAC 12T. Hmmm.

 

[dogman dan]

I tune my 9c 2812 down to 1500w for the hottest summer months. I could ride watching a thermometer, but I'd rather just ride.

In the colder winter months, I get away with dirt riding using a 40 amp controller at 72v. But to be honest, I likely don't pull more than 2000w very much of the time I'm running. Only the steepest walls cause that kind of watts. So cruising along, it's often below 2000w.

 

[auraslip]

my bike > https://sites.google.com/site/shelbyelectro/Bike-of-the-week/12---kiyohime

Run it at 4.5kw everyday. It gets up to 120c after about 10 miles though. (and my small battery goes flat)

2.5kw is probably the max you can run continuously with an air cooled 9c. Maybe more if oil bath.

Dogman is probably spot on with 1.5kw for a sealed motor. I'd have reservations about that on a hot day and/or with hill climbs. Best is to install a temp sensor.

Honestly, these motors are a lot of fun at first, but quickly loose their peppyness once they get hot. Not to say they are a dead end. But until kenye starts making active liquid cooling stuff, a more powerful motor is a good insvestment!

 

[dogman dan]

Yeah, In some ways, best to run them in a way that doesn't overheat them so much. That's why I fell in love with the slow windings for dirt riding. The kind of slow riding I do was hell on a 2807, causing it to run hot and sluggy.

Better running 1500w on a slow winding cool, and having it run nice, than running more watts into a fast winding and overheating it on too steep hills.

In winter, I get away with more because I can just find a flat road and cruise the motor cool again easy. Then go climb another hill.

I wish you could get a big honking 5000w rated motor that weighed the same as a 9c, but it ain't happening if it's copper and steel.

Definitely run a thermometer of some kind on a motor running above 1500w. Good to have a thermometer on any motor that is working hard, like a cross country bike climbing huge mountains even at 1000w.

It's all about equilibrium temperature. Under load, your motor will heat up and one of two things will happen. It will reach an equilibrium, where it's cooling as fast as it heats. Winter helps a lot with that, if the loads are not too much. Now the motor can go on infinitely without getting hotter, since it's temp has stopped climbing. Or it melts, because equilibrium temp is above 400F. By 451 the string tying the windings down combusts, and a bump is likely to shake the melted solder joints loose. Somewhere along the line, the laquer on the windings burns away and shorts the windings. Untill the windings short, it's all fixable.

If you are running 3000w or more, then it's just a matter of how long you have before the inevitable overheat, if you are actually pulling 3000w that much. A few 4000w starts won't kill your motor if you cruise at 1500. But if you are actually pulling hard most of the time, like on the racetrack, you get a few peppy laps, then get hot and sluggy, then melt. You can feel it coming. Fun as hell though, since 9c motors or thier clones are dirt cheap. Just keep the fun short and it's all good.

 

[pwbset]

Fun as hell though, since 9c motors or thier clones are dirt cheap. Just keep the fun short and it's all good.

And that's exactly why I'm leaning toward a 9C like 2810 since they are dirt cheap I can just see if it'll handle 2.5kw up an 8-10% for 15-18 minutes straight. If not at least I'm not out too much money. I really want to try a MAC 12T with the new clutch at WOT on 76v 40A around 30mph too 'cause that sounds like even more fun blasting up the mountain like that. 8)

 

[dougnutz]

Thanks for all the advice. After a bit of time playing with the simulator it seems to agree with everyone. Short bursts of 2500 watts are not bad unless the speed of the motor is really low such as climbing dirt hills.

In my particular use I cruise at 150-300 watts, unless it's a really windy day. But I do run with traffic for a little less than half a mile. For that sprint I'm seeing 2500 watts. I have never noticed any temp increase but the weather has been cool so that has helped I'm sure. As the weather warms up I'll keep an eye on it but it sounds like for short blasts it should hold up fine.

 

[Xanda2260]

Im hitting 3800w with mine, and run oit of battery before overheating. BUT, I live in the land of eternal drizzle and have no hills steaper than 4% or longer than half a mile.
I'm thinking 1600ft at 8% grade might be a bit much for a 2807.

 

[dogman dan]

For sure, a half mile of 2500w won't cook a motor that is rolling at least 15 mph. But likely you are rolling nice and fast at 2500w on the flat.

You have no worries, since your normal ride won't have the motor preheated much.

You'll love a 2810 on 72v for that climb to the ski area. It won't be super duper fast, but you'll climb cooler than you did with a 400 clyte for dang sure. Order it now though, or you won't get one. Once Methtek is out, nobody I know is stocking a rear 2810.

You can climb thousands of feet of vertical with 2807 9c motors, but you will want to pedal a lot to keep moving at 15 mph with that winding.

 

[Xanda2260]

For sure, a half mile of 2500w won't cook a motor that is rolling at least 15 mph. But likely you are rolling nice and fast at 2500w on the flat.

You have no worries, since your normal ride won't have the motor preheated much.

You'll love a 2810 on 72v for that climb to the ski area. It won't be super duper fast, but you'll climb cooler than you did with a 400 clyte for dang sure. Order it now though, or you won't get one. Once Methtek is out, nobody I know is stocking a rear 2810.

You can climb thousands of feet of vertical with 2807 9c motors, but you will want to pedal a lot to keep moving at 15 mph with that winding.

That's good to know, if I ever do find a big hill, keep above 15mph and it'll likely survive. Cheers Dogman, that'll stop me worrying!

 

[pwbset]

You'll love a 2810 on 72v for that climb to the ski area.

It is tempting especially with the recent oil bath cooling excitement. I just keep reading thread after thread about the 9c having massive power fade getting too hot on long, sustained climbs... though I suspect a lot of people aren't riding the throttle well & just dumping heat inefficiently at WOT and bogging it. I remember it taking me awhile to find the sweet spot with my 4011, but when I did I probably shaved 20-30 degrees off the top just with throttle management. That 4011 absolutely killed it at 84v25A, but I still had to help it a lot.

I have a price request quote into cell_man for a MAC 12T with upgraded clutch and phase wires. I really like the idea of no cog free wheeling & geared torque & at ~72v that 12T should maintain 20mph up those grades... plenty fast for me. If it can do it @ 1.5-1.8kw that would be even better. I'm done with monster DD motors... they're fun, but just too unwieldy.

 

[ian.mich]

what?? any 9c or pro 901 will take 4kw without giving two shits because if you actually sustain 4kw, you're going to deplete your batteries in no time.

 

[e-beach]

Honestly, these motors are a lot of fun at first, but quickly loose their peppyness once they get hot.

Heat takes the magnetism out of magnets. So if your permanent magnet motor gets real hot, it will loose it's "peppiness." Taking a neodymium magnet past it's Curie temperature of 608 degrees Fahrenheit (320 Celsius) allows the electrons to de-align.

Heating a magnet past its Curie temperature; the molecular motion destroys the alignment of the magnetic domains. This always removes all magnetization.
http://en.wikipedia.org/wiki/Magnet

That doesn't mean that the neodymium or what every your magnets are made of are dead though. They can be re-magnetized if you are crafty enough to build a magnetizer that will fit the magnets in your hub. It doesn't take long to magnetize neodymium, a second or two. It would take a nicely designed electromagnet to do the job, or perhaps a strong magnet on a spoke that can be pulled perfectly away from the magnet in the hub to realign the electrons in the north south polarity that was designed into you hub motor. Just don't forget to flip the magnet every other time..N..S..N..S.etc.

How easy can it be? Check it out.

http://www.youtube.com/watch?v=Q0kC2Oory5c

http://www.youtube.com/watch?v=AKmImCBrgbA

http://www.youtube.com/watch?v=ckSNA0MlcBE

http://www.youtube.com/watch?v=3omwHv3Cmog&feature=relmfu

PS If you have a pace-maker, do not play with magnets!!!

 

[Samd]

Someone above hinted at other brands like MagicPieIII (plus external controller). Any better or worse? Or much the much?

 

[neptronix]

A 9C can surely take a lot of power in a burst. How much of that power above 2500w is converted into heat, and how much goes to the ground in a 26" wheel is up for rigorous debate.

I found that cruising at 1000-1500w constant on flat land was OK on my MXUS ( 9C Clone; same stator and magnet dimensions ) for about 5-10 miles. It would sure produce a lot of heat on hills if given a lot of battery amps. Once i tried pumping 4000W continuous into it; it heated up to egg cooking heat in only a few minutes.

In a 20" wheel, it can definitely push some higher continuous power, and good torque too. If you have the opportunity to run a 9C in a 20" wheel, go for it

 

[neptronix]

Someone above hinted at other brands like MagicPieIII (plus external controller). Any better or worse? Or much the much?

The magic pie can certainly push some good continuous power, and shed some serious heat too. It's pretty dynamic, even in a 26" wheel. But it requires high voltage to really get the speed up. I believe that the 26" wheel does a meager 18mph on 36v?

 

[nechaus]

the 20inch pie imo is alot better than the 26inch pie, they are both still good , but the 20 inch you get the solid rim that works as a heatsink..
and its a fat rim

 

[Samd]

You got me thinkin Nechaus. I always thought those solid disc wheels the lycra folk use looked a bit naff, but maybe they'd make good heatsinks...

 

[amberwolf]

what?? any 9c or pro 901 will take 4kw without giving two shits because if you actually sustain 4kw, you're going to deplete your batteries in no time.

That depends on the size of your batteries. If your'e just using some little 44V 5Ah pack, sure.

I'm pretty sure I could melt (or at least damage) my air-cooled 9C 2807 before I ran out of power, with 20Ah at ~66V hot-off-charger, even if I only ran it down to 15Ah used. If I added on my other packs for more range, I just about guarantee it's destruction.

It gets too hot to touch the windings just doing stop-and-go traffic using only partial throttle for startups, trying to keep it under 2KW most of the time for acceleration, for 2.5 mile commute to/from work, max 20MPH speed, 14-16MPH average depending on traffic and lights. I want to measure it's winding temperature, but havent' yet setup temperature probes for this. (mostly because it takes a couple of hours to get the wheel off and back on the bike, not counting the time tot ake it apart and run the sensor wires thru it and moutn the sensor. but also because I don't yet have an appropriate sensor/thermometer).

I imagine if I let it run at the 4KW+ I get at full throttle from a stop, every time, or kept full throttle so I end up at 30-35MPH and try to cruise at that full throttle, it'd damage something quickly. (this is assuming I upgraded the phase wires, because the factory ones it has right now would melt insulation and short out long before the motor failed).


I don't remember what the wattage Dogman was running at the DeathRace last year, but he pretty well overheated (was smoking) his front 9C in the race, and probably still had plenty of battery left. I think it was around 3KW, though it might've been 5KW.


And both of thsoe sitatuions I describe above aren't using 4KW constant, just during the hard acceleration part, getting up to speed, repeatedly. If you put one on a dyno and put a 4KW constant load on it, I expect it'd smoke well before a "48V" (60-ish really) 20Ah pack ran out of power, even aircooled or oil-cooled. Some run even bigger packs.


Now, if you're talking 4KW *bursts* during acceleration only, and running less than 500W the rest of the time, like I normally do on CrazyBike2, then sure--I coudl do that probably all day long even in the 120F heat, and still not destroy teh motor, although it would likely smell funny.

 

[ian.mich]

what?? any 9c or pro 901 will take 4kw without giving two shits because if you actually sustain 4kw, you're going to deplete your batteries in no time.

That depends on the size of your batteries. If your'e just using some little 44V 5Ah pack, sure.

I'm pretty sure I could melt (or at least damage) my air-cooled 9C 2807 before I ran out of power, with 20Ah at ~66V hot-off-charger, even if I only ran it down to 15Ah used. If I added on my other packs for more range, I just about guarantee it's destruction.

It gets too hot to touch the windings just doing stop-and-go traffic using only partial throttle for startups, trying to keep it under 2KW most of the time for acceleration, for 2.5 mile commute to/from work, max 20MPH speed, 14-16MPH average depending on traffic and lights. I want to measure it's winding temperature, but havent' yet setup temperature probes for this. (mostly because it takes a couple of hours to get the wheel off and back on the bike, not counting the time tot ake it apart and run the sensor wires thru it and moutn the sensor. but also because I don't yet have an appropriate sensor/thermometer).

I imagine if I let it run at the 4KW+ I get at full throttle from a stop, every time, or kept full throttle so I end up at 30-35MPH and try to cruise at that full throttle, it'd damage something quickly. (this is assuming I upgraded the phase wires, because the factory ones it has right now would melt insulation and short out long before the motor failed).


I don't remember what the wattage Dogman was running at the DeathRace last year, but he pretty well overheated (was smoking) his front 9C in the race, and probably still had plenty of battery left. I think it was around 3KW, though it might've been 5KW.


And both of thsoe sitatuions I describe above aren't using 4KW constant, just during the hard acceleration part, getting up to speed, repeatedly. If you put one on a dyno and put a 4KW constant load on it, I expect it'd smoke well before a "48V" (60-ish really) 20Ah pack ran out of power, even aircooled or oil-cooled. Some run even bigger packs.


Now, if you're talking 4KW *bursts* during acceleration only, and running less than 500W the rest of the time, like I normally do on CrazyBike2, then sure--I coudl do that probably all day long even in the 120F heat, and still not destroy teh motor, although it would likely smell funny.

damage is not done until the windings reach 150C, an air cooled pro 901 can handles bursts at 8kw without issue. unless dogman was climbing pikes peak, i doubt he was running 3kw, 5kw sounds more likely especially in a race. I have sold numerous 901s with 12g phase wires, 20S lipo and 45A controllers, for peak of 3800w. i have no qualms about selling this to anyone, because i am confident that i will never have a smoked motor, especially considering the testing i have done. i took a 901 with a 100v60a controller, shunted up to 80a, ran the motor at full speed, put gloves on and held down the motor till it hit 7kw, sustained that until it had output 30ah. then ramped down the current and doing the same thing over and over. there is no chance that 66v would smoke a motor under those conditions

 

[Kingfish]

9C > 2.5 kW? Bah!

In the words of Samwise Gamgee: "Share the Load!"

[youtube]6sLJ0P_1dzU[/youtube]

Time to move to 2WD

hehe... KF

 

[ian.mich]

9C > 2.5 kW? Bah!

In the words of Samwise Gamgee: "Share the Load!"

Time to move to 2WD

hehe... KF

lmao but seriously 9c below 2.5kw is nonsense

 

[ian.mich]

This is all nonsense, running an oil cooled 1000w motor at 6kw here. done everything in my power to fry it, its still kicking it just as hard as ever.