BMC 600W vs Crystalyte 5304 @72V

[dirtdad]

Knoxie,

I got the impression from your signature that you had run the BMC with 72V for an extended time. Well, no matter, I am doing that now. I may post some reliability follow ups later. But the factory does seem to agree with you, they don't like to sell more than 48V controllers to go with the motors, so neither do I, but there are always modders who are interested in what you can get away with.

[knoxie]

Hello Again

No the signature is just representative of the video kind of so people who see the video then come here know who I am. You can of course run the Puma/BMC at 72V but they just dont last very long if used for extended periods, doesnt look quite as cool in the signature

The first BMC motors came with a 37V 15A controller and the performance was pretty unremarkable, most people swap them out for xlyte or infinion of course and 37V 35A is a lot more respectable and a lot kinder on the motor. There is no doubt that 72V 35A is exhilarating on the Pumas and some have held up, Jozzers KMX seems to still be holding together but many havent and those that are a little heavy on the throttle or the bike have found them to be very easy to break

I think in time a suitably rated geared hub motor will surface, there is a market for one thats for sure, my concern with selling the motors is that folks will abuse them and then want repairs and or replacement under warranty, its not the motors fault in many respects as they were only ever designed to run at 250W, the fact that they break when running at high power levels is to be expected in many ways.

I still think they have a place and can be reliably run at 600W which isnt shabby at all and in fact is nearly 3 times over the legal limit here in the UK and almost up to the limit in the US, keep em legal keep em reliable!

Knoxie

[Ypedal]

Those BMC's look just like the eZee motors, made by the same people imo, and i agree with Knoxie on this one, you can push them hard but not harsh..

The gearless hub motors suffer no ill efects from bad throttle control compared to a geared setup.

Guys who treat the Ebike like a Motocross by blirping the throttle ( is blirping a word ? ) instead of rolling on smoothly and either staying ON or OFF but not constantly mashing it..

Just like pedaling by kicking the pedals forward and backwards in half turns ruins freewheels.. and shifting while pedaling hard up hill ruins derailers..

[knoxie]

Hi Y

Yes good analogy there! the way they are ridden also is a big factor, a lot of folks have had problems that have largely stemmed from the fact they never ran torque arms as well, motors spinning and ripping cables apart. I think after you have owned and fixed your own rides you tend to treat them with more respect and they in turn reward you with hours of fun and reliability.

Not all none geared hub motors are faultless either though and can still fail if abused, Jozzer has just finished repairing a load of 4 series motors that were being used with big lead acid batts on electric rickshaws, they abuse them pretty badly whapping open the throttle and running lots of chubby tourists about the place, I think on 6 of them they got so all the magnets came un stuck and the motor just grinded them round.

He split the motors and used some high temp high strength adhesive on them which seems to have done the trick, again the Chinese dont over engineer anything, they shouldnt have to either in reality and I do think a lot of what they sell is pretty poor quality but then it is cheap, you want high quality you have to pay.

I think the X5 takes a lot of beating and I dont see any competition for it out there if high power and combined reliability are your over riding concerns. Ask Justin! his one took him a very long way indeed.

Knoxie

[dirtdad]

I believe the correct term is blipping the throttle. Urban dictionary has other ideas, however. Ok, no bliping or blurping the BMC. Got it.

[GGoodrum]

I still think a geared hubmotor could match a typically over-powered x5 setup, but maybe the 600W model is not the one. The new 1000W model, if it appears, sounds like it would handle the higher power, from an electrical point-of-view, but the unknown is still going to be the gears, I think.

In general, I think adding gearing to a smaller motor can go a long way towards making up the torque advantage that a bigger motor, like the x5. For instance, running a Cyclone 1000W motor through a Nexus 3-speed hub produces a pretty amazing amount of torque. I had a 5303 on my 20" Mariner folding bike, which ran on a 24s4p 72V a123 pack. It had blistering performance. I've since replaced this setup with the 1000W Cyclone, which comes with a 48V/55A controller. With a 16s4p a123 pack, this puts out about 2700W peaks. There is about a 7:1 gear reduction to the front sprocket, pretty much 1:1 to the back sprocket and then the Nexus hub is 1:1 in 2nd, 0.75:1 in 1st and 1.33:1 in 3rd. Even on 48V, this has more torque in 1st gear than the 5303 on 72V/50A. It also has roughly the same top-end in 3rd gear. The point is that gearing can certainly help narrow the performance gap between smaller and larger motors, but in the case of the BMC's the weak link seems to be the planetary gears.

-- Gary

[Microbatman]

DirtDad Great info thank you for the test.


What are the changes between the old 400W BMC and the 600W BMC?


Are they the same casing?

[Knuckles]

All I can say is "METAL GEARS and BIG FAT PHASE WIRES"

PMGR is more BANG for the MASS of motor but DD rules for top speed on the FLAT.

IMHO

[dirtdad]

What are the changes between the old 400W BMC and the 600W BMC? Are they the same casing?

The differences are improved materials and construction: composite gears, silver/teflon phase wires, bigger stronger magnets, tighter tolerances, etc. The casing has the same external dimensions. But much of the shell was simply made and unnecessarily thick. So it was thinned out in non-structural areas. The end result is a motor that is the same weight and size that delivers more power. The differences may not sound like they add up to much, but the proof is in the results, this little motor really flies.

[dogman]

Great thread guys! I think what a lot of us want to know is how the new gears hold up. All metal is a good solution, especially for a motor to be used off road, like a motorcycle. But for my 29 miles a day, a plastic gear that doesn't go to peanut butter so easy is sounding like something I'd rather listen to for two hours a day. If the new gears can take 72v for a substantial length of time, say 500 miles, I think I'd be confident to run one at 48v.

[Knuckles]

Great thread guys!

This is a great thread because it gets to the heart of the matter.
Clearly we are way beyond the 2002 e-bike law (20MPH and 750W).
It's about performance now, motor mass (and cost), and dealing with China, and gettin' this stuff into the USA.

Recently we modified the Infineon to be "soft start" and now (apparently) all the Infineons
are now a softer start up when you gun the throttle.

My "softer gentler" Infineon still does my front (Direct Drive) "Saw Blade of Death"
at 72V but I never had a problem with the hard start anyway.
A "kinder gentler" "Saw blade of Death"?

But for geared motors "soft start" does appear to be an advantage.
So Mark in UK and dirtdad are working on testing the PUMA and BMC on the soft Infineon (respectively).

I wish I could be more help. But I don't have a PUMA or a BMC.
I got 4 DD motors, 1 rear Bafang, plenty of Infineons though.

But for what it's worth my single steel gear in the Bafang PMGR "takes a licking" and "keeps on ticking".
(and no bearing in the gear no less - FnA!)

btw ... be nice to Jason (E-BikeKit.com) ... he manages an import business ...
http://www.kraftglobal.com/index.html
We may have a use for him in the future!

[Bill Best]

A "kinder gentler" "Saw blade of Death"?

Ha-ha! That's hilarious!

I've been pretty impressed with the power of my 5304 @ 72V 48A in a 20" wheel. I'm using it with a trike, so there isn't much weight on the front wheel. I'll be going through quite a few sets of tires considering it burns out quite often.

[methods]

What's your opinion on the continuous power handling of the X5, Gary? 6.5kW is impressive, but can it be sustained?

If you run 6.5kw all day the motor gets so hot that you cant touch it.
I have not measured the temperature.
I can get it to pull 6.5KW up to maybe 20mph then it rolls off to around 3KW
Has not failed on me yet though after hundreds of hard miles.
Wires are 10G up to the axle

btw: that hall sensor that died was due to a poor solder joint on the sensor. After I removed it, it was still functional so it was not the heat that killed it.

-methods

[Doctorbass]

HUmmm.. I would really love to compare that 1000W BMC with max possible power on it and a 5305 inthe same test conditions!!

I would really love that Who have one here.. and from them...who live closest to Quebec city?

Well.. i'll search on youtube to see what could have been filmed about that motor..

I know BMC seems to have torque.. but does prople that tried tehem already also tried an X5 04 or 05 at FULL power?

Doc

[dirtdad]

A great comparison would be the 600W high torque BMC vs a torquey X5 like maybe the 5305. I have been riding a 600W high torque @48V, and the torque really is very impressive. Top speed is only about 25mph, but it has great acceleration. I tend to burn a lot of watts/mile because one of the most fun things about it its acceleration, which really consumes the watt-hours. It makes a great off road motor, depending on the terrain, since speeds off road tend to be lower and the hills can be steeper.

Alas, I dont have my 72V pack around to test with any more. In any comparison of the BMC 600W and any X5, you have to take into account the BMC weighs less than half of the X5 class. The X5 does ultimately outperform the BMC, but not by much.

[The Stig]

Anyone else have comments about the BMC 600W?
Who are they best bought from? What is the optimal controller?

[dirtdad]

I have now also tested with a Crystalyte 36/72V 40W with 4110 mosfets. I have tested with the high torque 600W. Max speed is less than 35mph, but acceleration is tremendous, and kw/mi is very good.

[www.recumbents.com]

I have the BMC 600 watt, but have not experienced weather conducive to extensive testing yet this year in the Chicago area. I'm using it with a the same Crystalyte 40A controller as Dirt dad (Stock MOSFETs) and a Ping 48V20Ah battery. Around the block testing shows this setup is good for 30MPH.

The power wires to the motor seem a bit wimpy, but they are pushing what I think is 3 phase AC to the motor (right?). AC wiring does not need to be as heavy duty as DC.

I bought it the guys at www.hi-powercycles.com, who seem knowledgeable about their product and are striving to deliver a high performance product.

I like the fact that you can put an 8/9 speed cluster on the hub, and that a disk brake bolts right on. hi-power installed the 9 speed cluster for me. I like it because you can't tell it's an e-bike.



Cranking it up in the basement with the brakes on I saw a max of 80A on the CA, but that was with the shunt value set to 1.0. I have now set it to 1.2. I'll post more stats when I can take it for a real ride.

-Warren.

[www.recumbents.com]

Ok, FINALLY the weather coorperated enough for me to ride the BMC 600 e-MTB with Ping 2.0 48V battery to work and back. 30 degrees F in morning (frikkin cold), but it warmed up to 70 F on the way home. The ride is about 7 miles each way, in and out of a river valley, city traffic.

So... round trip stats!

Amp hours used: 15.65
Watt-hours: 724.43
Watt per mile: 44
Negative or regen current: -16.9 A
Max current: - 79.66 A
Minimum voltage: 26.5V
Max speed: 34.4 MPH Average speed: 24.1 MPH
Trip time: 40m 59s

The bike cruised at or close to 30 MPH, went up hills around 25 MPH, and accelerated quickly. Very nice. While the bike doesn't go faster than my 24V e-recumbent, it does get up to speed MUCH faster, and goes up the hills much faster.

-Warren.

[justin4u]

I have a question about the review at the top of the thread. On level ground both motors could hit 40mph. Why only 11/13 mph going uphill? What is the limiting factor battery, controller, or motor.

In my experience with electric motors in the RC world they will draw as many amps as required to spin at the rated KV (rpm per volts). If the system is over loaded three things can happen

1) the motor moves outside of its efficiency curve and generates heat instead of power
2) as the amp draw on the battery goes up the voltage starts to drop until you hit a low voltage cut off
3) The controller limits the system to XX Amps

Example

100KV motor (100 rpm per volt)
12V battery
10” prop

This system will draw 20Amps and spin the prop at 1200 rpm

If you increase the size of the prop to 15” the rpms will remain the same but the Amp draw will increase to 40Amps.

Am I missing something???

[Ypedal]

Number 3 is your horse !

The controller limits the amps.. speed goes down as a result.. as long as the hill is not steep enough to force the controller to limit amps, you are in the efficient zone, once the current limitting starts it's a factor of momentum and lenght of the hill hehe..

[jag]

I have a question about the review at the top of the thread. On level ground both motors could hit 40mph. Why only 11/13 mph going uphill? What is the limiting factor battery, controller, or motor.

In my experience with electric motors in the RC world they will draw as many amps as required to spin at the rated KV
Example

100KV motor (100 rpm per volt)
12V battery
10” prop

This system will draw 20Amps and spin the prop at 1200 rpm

If you increase the size of the prop to 15” the rpms will remain the same but the Amp draw will increase to 40Amps.

This is exactly true only for an ideal motor with zero internal resistance and other load dependent losses. It can be approximately true for a very good motor. However, likely you have a small rpm drop as well as a small voltage drop.

If the system is over loaded three things can happen

1) the motor moves outside of its efficiency curve and generates heat instead of power
2) as the amp draw on the battery goes up the voltage starts to drop until you hit a low voltage cut off
3) The controller limits the system to XX Amps

With very good (low internal resistance) battery packs and motor number three is likely the cause as Ypedal suggests. However, in practice all factors play a role. For example top speed of my 9C with 60x 8Ah NiCd cells (nominally 72V) is 50km/h on the flats, but drops to 30km/h up the hill near my house. (Which is of course not the same hill tested on in the previous post but serves as an example). On the flats the Cycle Analyst measures 700-800W at top speed. Up the hill it is about 1600W. Voltage on the flats is about 70V and up the hill about 60V.

Quantifying the impact of your three limiting factors:

1. Motor loss: Amperage more than doubles. Hence losses in the motor due to the internal resistance more than quadruples
(p=I^2*r; this would be a simplistic model of the motor, but seems quantitatively a reasonable approximation here). I don't know the Ohm value of the internal resistance of the 2709, but a reasonable guess is that internal resistance losses at 800W on the flats would be in the range 100-150W, and hence up the hill at 1600W losses would be 400-600W.

2. Voltage drop is 10V, a 14% decrease. This generates about 300W heat in the battery packs (so they get warm to the touch).

3. My controller is 30A, and amperage up the hill is about 26A, so the controller shouldn't be limiting. I'm not sure if due to production variances it is limiting anyway. Haven't modified the current shunt to see if it makes any difference.

Bottom line is though that of the 1600 W the CA sees put into the motor, maybe 1000-1200W gets turned into useful mechanical work pushing the bike forward. Motor losses at 400-600W and battery losses at 300W are not insignificant.

To improve performance uphill, one could get a stronger motor, better battery pack, or higher current controller if it is current limiting. Which makes most sense would depend on the particular setup and what part is the weakest link in it.

[Doctorbass]

Current limit is the real factor you must keep on every comparaison! I agree with Ypedal.

To give you an exemple, my 5305 run at 70-75 on flat no wind 3500W
and on the heavyest hill i found in Quebec city it's 55km/h at 5500W continuous

Doc

[justin4u]

Does anyone sell a controller that will work with the BMC 600W that will fo 72V at 80+ Amps? All I see is 40Amp controllers.

Thanks

[dirtdad]

I sell one that will go to 65A, and with a little mod-ing should easily be able to handle 80A. However, the motor is only warrantied for up to 48V.