BMC 600W vs Crystalyte 5304 @72V

[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.

[grandmasterE]

Is this motor still in use? How many miles on it? How is it holding up?

E.

[dirtdad]

I used the 600W high torque with 72V and 20 and 40A controllers. Note that this voids the warranty. No problems in several months of use. 72V with the high torque motor produces speeds just over 30mph. With 40A it accelerates like a kick in the pants and climbs hills with nary a complaint.

I just today switched to the 1000W motor for testing. It seems to have similar speed/Volts as the 600W high torque with both the 20 and 40A Crystalyte controllers I have. Supposedly it delivers higher speed above 40A.

BMC and others are working on a bigger controller to mate up with the 1000W motor, and I will try a stock 18FET Infineon eventually.

[grandmasterE]

I used the 600W high torque with 72V and 20 and 40A controllers. Note that this voids the warranty. No problems in several months of use. 72V with the high torque motor produces speeds just over 30mph. With 40A it accelerates like a kick in the pants and climbs hills with nary a complaint.

I just today switched to the 1000W motor for testing. It seems to have similar speed/Volts as the 600W high torque with both the 20 and 40A Crystalyte controllers I have. Supposedly it delivers higher speed above 40A.

BMC and others are working on a bigger controller to mate up with the 1000W motor, and I will try a stock 18FET Infineon eventually.

How many miles would you estimate you put on at 72V 20/40A? In what type of terrain? Stop and go, or just cruising? What is your estimate of average load (bike+rider+cargo) weight?

Are you able to compare 0-10 mph and 0-20 mph times for the 600W high torque and the 1000W high speed with the same a battery and controller? Have you also tested the 600W high speed model? How does it compare?

Also, it's not clear on the website, but do you sell the 600W speed or torque model?

Do you know if the difference between the speed and torque model for 600W extends beyond gear reduction ratio? I'm trying to figure out if it is the exact same motor with a different gear ratio or not (info is hard to come across).

Any info is appreciated.

E.

[dirtdad]

How many miles would you estimate you put on at 72V 20/40A? In what type of terrain? Stop and go, or just cruising? What is your estimate of average load (bike+rider+cargo) weight?

Are you able to compare 0-10 mph and 0-20 mph times for the 600W high torque and the 1000W high speed with the same a battery and controller? Have you also tested the 600W high speed model? How does it compare?

Also, it's not clear on the website, but do you sell the 600W speed or torque model?

Do you know if the difference between the speed and torque model for 600W extends beyond gear reduction ratio? I'm trying to figure out if it is the exact same motor with a different gear ratio or not (info is hard to come across).

Any info is appreciated.

E.

I will test range today. We only list the 600W high speed. We have found little demand for the high torque, but we can order it on request.

The 600W high torque has the same gear reduction ratio as the 600W high speed. The 600W high torque achieves higher torque electrically, not mechanically, through more windings on the motor. And it has a black finish. Otherwise, it is the same as the 600W high speed.

[snowranger]

Dirtdad,

Which V2 motor is closest to the V1 version in performance? My V1 tops out at 27 mph with a 52 volt battery and 30 amp e-crazyman controller.

[999zip999]

Does anyone have any thing to add to this great forum. The highest safe amps. at 60v on the 600 h.s. ?