MAC/BMC maximum continuous watts?

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alfantastic   10 kW

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MAC/BMC maximum continuous watts?

Post by alfantastic » Jul 14 2012 8:12am

Considering these motors are fairly similar, what's the maximum safe continuous wattage these can be run at fairly reliably?
I realise that the harder you run them close to their max, plus road conditions, all play a part in their demise, but maybe 15,000 miles sound ok?
I would expect the gear mechanism to need replacing, but would the main motor survive?
Also, would the maximum rated power vary between different motor winds?

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Re: MAC/BMC maximum continuous watts?

Post by mark5 » Jul 14 2012 1:11pm

alfantastic wrote:Considering these motors are fairly similar, what's the maximum safe continuous wattage these can be run at fairly reliably?
I realise that the harder you run them close to their max, plus road conditions, all play a part in their demise, but maybe 15,000 miles sound ok?
I would expect the gear mechanism to need replacing, but would the main motor survive?
Also, would the maximum rated power vary between different motor winds?
Wattage level for reliable operation has come up before as here between knoxie and nonlineartom:
Re: Mac10t verses HS3540 on 1600 watts
http://endless-sphere.com/forums/viewto ... 79#p598977

I think I have read Cell_man write approximately the same watts before.

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dogman dan   100 GW

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Re: MAC/BMC maximum continuous watts?

Post by dogman dan » Jul 14 2012 1:46pm

The motor rating.

Or, till the motor reaches an equilibrium temperature for the continuous wattage you are pulling that particular day, in that particular days weather.

That's about as cut and dried as you can say it. However, quite a few more watts can be run untill the motor temperature reaches whatever you are calling the stopping point. It may not be continuous at all, but it works out that way if your battery runs out before the motor overheats. I don't know about gearmotors, but 1500w will almost never damage a dd motor that is run at 15 mph or more.

I wouldn't hesitate to run 48v 30 amps on a Mac, if I ever get one.

Really, it's not a how many watts question in the least bit. It's a how hot can your run continuous question. That is more cut and dried for sure. Keep a motor below 200F and you are really unlilkely to see any damage, not even browed windings.

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neptronix   100 GW

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Re: MAC/BMC maximum continuous watts?

Post by neptronix » Jul 14 2012 3:39pm

How many amps the MAC/BMC motors can take continuously will vary based on wheel size, winding, and voltage.. no easy answer to that question :)

I've had no problem running 35-39mph on 15S with an 8T in a 26" wheel for 30 minutes at a time, with pedaling on mildly hilly terrain.
2600w peaks, 1000w-1700w constant is fine.

The MAC/BMC motors are hard to melt, but you can do it climbing very steep grades for long periods of time with >1500W constant.

Keep an eye on the motor heat and you'll figure it out. I'd say this motor is good for 30-35mph reliably, going off my experience.
"Love and compassion are necessities, not luxuries. Without them, humanity cannot survive." - Dalai Lama

My first major build: 1.6kW 8T MAC motor on a Trek 4500.
The new all-arounder: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: 20" eZee on a Cannondale Semi Recumbent.
Whipper-snapper: ? on a lightweight BikeE Semi Recumbent

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Re: MAC/BMC maximum continuous watts?

Post by dumbass » Jul 14 2012 4:20pm

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Last edited by dumbass on Jul 15 2012 7:44am, edited 1 time in total.

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Re: MAC/BMC maximum continuous watts?

Post by DAND214 » Jul 14 2012 6:49pm

I like my MACS!

8t 15s lipo 26" wheel and I can't tell what the controller is set at but it's less than 50a as I have done in 2 clutches when the power is too high. Heat hasn't been the problem as I ride mostly under 1000wats which is faster than I should. 2500w on WOT and it tapers off quick when it hits 20 to less than 500w, 1200 or so for 30+.

i have had a hard time getting a smooth controller setting since we can't read what is in the controller after it's been flashed. One MAC is smmoth from 0 to 40 and the other I can't get the same way, YET. I am writing down my # as I try them, the list is getting a little long.
So stay under 45a controller and the Mac/BMC should live a long time.

I still love my MAC!
2 MACS, 1 BMC V1, 2 BAFANG's, 1 CUTE and 5 DD's in the stable.
Boy am I glad I can't count.

Dan

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neptronix   100 GW

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Re: MAC/BMC maximum continuous watts?

Post by neptronix » Jul 14 2012 7:40pm

I run 42a battery x 95 phase amps ( 2.25-ish battery phase amp ratio ) on a cell_man EB3 controller. Very smooth start! have not gone through a clutch yet, but blew through the original white gears after a year of use immediately after i tried running the MAC on 4kW.

It's been a great motor, i think i've had good luck because i've ran it juust below the breaking point.. :lol:
"Love and compassion are necessities, not luxuries. Without them, humanity cannot survive." - Dalai Lama

My first major build: 1.6kW 8T MAC motor on a Trek 4500.
The new all-arounder: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: 20" eZee on a Cannondale Semi Recumbent.
Whipper-snapper: ? on a lightweight BikeE Semi Recumbent

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Sacman   10 kW

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Re: MAC/BMC maximum continuous watts?

Post by Sacman » Jul 14 2012 8:38pm

In the past 3.5 years I've owned 5 BMC motors (2 BMC V3, 2 BMC V2-speed, and 1 BMC V2-torque) and have racked over 28,000 commute miles with them. My favorites are the V2-speeds. I've never had a gear or clutch blow out on me, with any of my motors. I think I'm able to get good long, reliable use out of these motors because I use them primarily for commuting and I don't abuse them nor pump too much power thru them.

While riding on my long commutes I mostly cruising and only putting 700-1100watts thru the motor. When I hit steep hills I can crank the power up to 2000watts for for up to half a minute or so but then back it down to below 1300watts for fear of overheating the motor. I've always wanted to put a thermo sensor in these motors so I know for sure when I'm in danger of overheating but I never did.

Worst failure I ever had with these motors was a bearing on the side cover failed, scrubbed and seized. That was on one of my V3 motors that had about 8,000 miles on it when it failed.

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Alan B   100 GW

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Re: MAC/BMC maximum continuous watts?

Post by Alan B » Jul 15 2012 1:02am

Ilia of ebikessf has a lot of experience with the BMC. He recommended a max of 1500W for the one he sold me.

It boils down to efficiency and dissipation. At low speeds with high torque loads the efficiency drops and they can only dissipate a few hundred watts, so as efficiency drops the max safe power also drops.

So far I've run 1,000 watts max and the motor has not warmed up much at all.

It takes time for the heat to propagate out of these motors, so judging the temperature from the outside is not very accurate.

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Re: MAC/BMC maximum continuous watts?

Post by mvly » Jul 15 2012 1:56am

I have ran my BMC v3 at 1600W. But I made sure I was always above 25mph. Anything slower, I drop it to 1000W and pedal assist. This only happens when I am going up a hill. So far 2K miles and no problems other than broken clutch due to the potholes and going over them at 35mph. I say keep it around 1.5KW max and keep your speed above 25mph and you should be fine if you have a V3 or V4S or V4C BMC or the 8T or the 6T MAC. If you have the V2T or the V4T BMC and 10T MAC, then maybe you can have it a bit higher, but I would keep it below 1.8KW for sure.

If you want high power go direct drive. I also have a HS3548 and I put 3.7KW into it and it is fine. I even run it 2KW continuous and no problem. Same rule about keeping the motor moving applies here. If I go slower than 25mph, I drop the power to 1.3KW and pedal assist.

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Re: MAC/BMC maximum continuous watts?

Post by Bullfrog » Jan 22 2020 5:06pm

Yes, I know this is an old thread.

Wanted to add a little info from the Grin Tech web site that indicates the answer is 1,000 watts.

The MAC and GMAC are identical as far as how hot they'll get when riding along under steady state conditions.

Here is a link to where I got the info: https://www.ebikes.ca/product-info/gmac.html

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dogman dan   100 GW

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Re: MAC/BMC maximum continuous watts?

Post by dogman dan » Jan 23 2020 7:52am

8 years later, we can add this info as well.

Mostly, with the 500w rated geared hub motor class, it depends on the load. In general, you can feed them 22 amps of 48v, or about 1200w, provided the grades are under 10%, and the weight of the entire system including the rider is under 300 pounds. This results in about 1000w continuous, when going up longer hills. They tend to pull more like 800w, if its flat, at max speeds.

This is the number E bikekit came up with, after I did testing to destruction with 400 pound loads.

It boils down to this,, not how many watts you are feeding it, but how many watts are you wasting into heat, after you overload it. Don't overload it beyond 300 pounds, and 1200w limited by controller amps is no problem. If the terrain is pretty flat, it can even have 400 pounds and get away with it,,, or,,,, 1500w.

But yeah, if you pull trailers,,, limit to 1000w makes a lot of sense. 48v 20 amps controllers, or 36v 30 amps. And then find a way around that hill.

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Re: MAC/BMC maximum continuous watts?

Post by AHicks » Jan 23 2020 9:11am

I can add that I'm 310lbs, and the bike is 65lbs. I have the controller (KT w/35a max) set to limit my max wattage to about 1200-1300w at WOT.

I spend a lot of time in a coastal area with some pretty big hills, big enough where a 1500w direct drive would be totally out of steam at the top while pedaling as hard as I can in 2nd or 3rd gear. With a swap to the MAC 12T and NO other changes made, the MAC 12T powers right through this same scenario, and not only that, battery life has gone from 25 miles or so reliably, to 35 miles. Yes, the MAC is working great.....

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dogman dan   100 GW

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Re: MAC/BMC maximum continuous watts?

Post by dogman dan » Jan 24 2020 8:11am

That shows that my test conditions, were as bad as it gets, while your environment allows a bit more weight.

I was doing my motor tests to destruction in 5% humidity, which greatly hampers motor cooling, and 110f weather. And my hill was 3 miles long, at 5% to 8% grades. In my test, 400 pound load melted the motor quite quickly, running 1000w continuous. It was lugging down to 5 mph pedaling hard, too slow for a 10T motor.

It easily made the top of the hill at 300 pounds though. So EBK set a 300 pound limit on warranty for their 500w geared motor, similar to a MAC 10t.

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Re: MAC/BMC maximum continuous watts?

Post by AHicks » Jan 24 2020 10:21am

Good thought! My normal conditions:
Coastal area I'm in is north central Florida Gulf Coast, and I darn sure won't ride in 110 degree temps! Anything much over 90 will have my bike parked. MUCH higher humidity levels though. Hills aren't 3 miles either. Maybe a bit steeper, but never more than a mile long, generally much less, like a half mile. Think of an area that may have been sand dunes at one time, now covered with grass, pine and oak with a few palm for good measure (to remind you that you are in Fl.). -Al

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dogman dan   100 GW

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Re: MAC/BMC maximum continuous watts?

Post by dogman dan » Jan 25 2020 8:06am

Yeah, I darn sure don't ride in 110 either. But I did for the testing. I live in a good place to kill motors. hot desert, and a mountain pass starts 3 miles from my driveway. So I could explore the absolute upper limits for EBK, giving them conditions far worse than most. Steepness matters though, most of the warranty claims on kits came from west virginia, where ever hill is 10% or more.

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