BMC V4C geared hub motor test ride.

[Neophyte]

Took delivery recently of a kit based on the new BMC V4C geared hub motor.

A 26" rear wheel build to be run at 48V and 20A.

Purchased from Ilia Brouk of [ Ebikes SF ].

Initially, the kit was to make use of a Lyen 12FET sensored controller but as it turned out there were problems. Controller was fine with the original V2 motor series but not with the new V4C. And, so, was exchanged for a 25A 12FET Crystalyte unit which exhibited no problems in use.

As for the first test ride?

The initial objective being to compare the V4C to my eZee kit.

With stellar results…

Increased efficiency over my eZee up to the 30% area.

A 46 km trip seeing 5.6 Ah drawn.

[ 8.2 km/Ah average ]

My body weight = 88 kgs.

A trip that included some occasional light pedalling over rolling terrain with numerous WOT tests. More than half the distance travelled being into a 20 km/h headwind. Average speed was in the 28 km/h area.

And at, again, 48V and 20A unassisted top speed was 47 km/h on flat and level terrain in the calm [ 43 km/h into the mentioned headwind ].

A 100 meter 6% grade was climbed unassisted [ WOT ] at 31 km/h.

WOT usage never seeing north of 750W.

My eZee kit, on the other hand, shoots north of 900W climbing that same grade unassisted at WOT [ 22 km/h ] while unassisted top speed is in the 40 km/h area on flat and level terrain in the calm.

Came as a complete, and hugely welcome, surprise to me that the V4C would be more efficient than my eZee given that the former is rated continuous 1,000W to 1,750W with peak in the 2,500W area while the latter is rated 500W continuous with peak in the 1,050W area.

And, so, just thought I'd make mention should anyone be interested.

The V4T, V4C, V4S series being relatively new to the market.

 

[Phoebus]

Indeed, I've had much success with these motors from ilia as well. These motors are extremely resilient in my experience.

 

[LegendLength]

Thanks for the review it's good to see information about these news motors. But I'm wondering about the efficiency / range you mentioned:

to be run at 48V

A 46 km trip seeing 5.6 Ah drawn.

So that's 269 Wh for 46 km which is 6 Wh / km or 10 Wh / mile. Are you sure you have those figures right because it seems really low. For example with my 9C + 12 fet lyen controller I use 500 - 600 Wh for 40 km with some pedaling. Maybe it's just one of those things that depends a lot on terrain and pedaling so can't be compared so easily.

 

[Neophyte]

Yep.

The presented numbers are indeed accurate. Both kits coming complete with a Cycle Analyst unit. The ride route I took being one that I ride often. Am totally familiar with. And I was told to expect improved efficiency over the previous BMC geared motor series but while I waited to take delivery my thoughts were that there was no way that the efficiency of my eZee kit would be totally eclipsed. Was a definite concern to me.

What I was seeking most in ordering the kit was a higher top speed. Not anything extreme but in the 45 km/h to 50 km/h area and I got just that. I had found the 40 km/h limit of my eZee kit to be not enough at times. Moments when I needed to scramble for one reason or another. And with that said it's also worth noting that the rate of acceleration to top speed of the BMC kit is about double what the the eZee can do.

Am totally pleased and will be out soon for another ride. Just as soon as the rain lets up. My eZee kit is my wet weather ride. My BMC will only be used on dry days.

 

[neptronix]

ilia from ebikesSF noted that there was no efficiency difference between the BMC v2/v3 and v4 motors.

http://endless-sphere.com/forums/viewtopic.php?f=2&t=33787

That's all i know.

 

[Ypedal]

can you give us the no load speed, voltage, and amp draw of both motors ?

same bike or different bike ? ( tires *( inflation level and type ) , total weight.. )

 

[Neophyte]

I can't speak to a direct comparison between BMC geared motor series but it is worth noting that Ilia's testing involved the V4T and a Lyen controller over strictly uphill terrain.

As for the involved bikes?

Same platform.

Giant Sedona LX [ 2012 ]…

http://www.giant-bicycles.com/en-ca/bikes/model/sedona/9786/49386/

Same setup in general. The primary difference being a 3.8 kg 10Ah battery [ BMC ] vs. a 7 kg 20Ah battery [ eZee ].

As for the no load numbers?

Will post soon.

 

[MadRhino]

Until proven with another test with reliable data, I will consider that you CA was not properly calibrated.
Your power usage for this ride as you described it, is too low and require a comparison test.

 

[Ypedal]

agreed.. 6wh / km at 40 kph only happens with pedaling, as soon as you factor in human legs, motor efficiency figures are not accurate.

 

[French]

Until proven with another test with reliable data, I will consider that you CA was not properly calibrated.
Your power usage for this ride as you described it, is too low and require a comparison test.

Exactly my suspicion. Need that shunt value adjusted properly. 20amps * 48v = 960watts. You'll know it's not calibrated correctly if you run your battery out, but the readout is only showing ~55% of what you would expect. Also, the cycle analyst is probably only showing max Amps at around ~11, where it should be reading the 20amp from the controller.

 

[Kris B Krunch]

That's what I thought too, infact just picked up my V2t from Ilia today and just got to mounting it in the frame and testing things out. Be good to hear any develpments in the geared hub world because I'm already looking forward to converting my kona stinky next to a higher powered rig than my comuter rig I'm starting with.

 

[Neophyte]

Okay.

Finally got things sorted out.

The sharp minds here were right once again.

CA RShunt value was set originally at 2.31 mOhm. Which, seemingly, is the correct setting for the original Lyen controller which was again problematic in use. The replacement Crystalyte controller, on the other hand, called for a 1.25 mOhm CA setting. And with the calibration set right I set out on the second test ride.

This time taxing the system to a far greater degree than previously. Most of the ride being into a 25 km/h headwind with much less pedalling [ approx. 15% of the distance covered ] and following a different route. One that was 30% within 'stop and go' city limits and 70% outside of those limits with far more hills to climb. And at no time did I assist the system up any of those hills. Additionally, there were more and longer WOT tests [ up to 5 km in distance ].

And all of it again at 48V and 20A but with this time a 20Ah battery pack.

The final tally being 79 km covered with 19.5 Ah drawn.

[ 4.05 km/Ah average ]

[ 11.85 Wh/km average ]

Average speed was 31 km/h while top speed was 46 km/h [ wind was broadside at the time ] and I later upped the CA amps limit from 20 to 25 to test that outcome with no improvement. And very likely due to the fierce headwind conditions of the time. Will test again under calmer circumstances as I was told to expect a speed premium at the 25A setting. Greater than 48 km/h. We shall see.

And this time the watts reading maxed out at 1,046W which isn't surprising given no pedalling up steep and lengthy grades at speed. The system fading far less than does my eZee kit. There being a vast difference between 500W continuous and 1,000W.

My planned third ride will involve waiting for much calmer wind conditions and will be at a reduced average speed with more pedalling which is my usual manner of riding [ 25 km/h area ].

My expectation, given the above, is that my BMC will be overall more efficient than my eZee.

The one downside in all of this being the noise level. The BMC's gear material being harder than nylon as explained by Ilia. My eZee system being noticeably quieter.

And with that said I'll make mention of the fact that my next kit will be a Crystalyte HS3540 [ 26" rear ] from Justin and crew at Grin. But before I make the purchase I have a few questions that I'm hoping those in the know will respond to…

1] How truly quiet are these motors compared to geared?

2] Does the regenerative braking function tend to seriously loosen the axle nuts?

3] How comparatively efficient in general is such a system if again run at 48V and 20A?

4] What top speed can be expected at 48V and 20A under ideal route conditions? [ And, yes, I've run the simulator but would like a little real world input. ]

Thanks in advance.

 

[mvly]

Okay.

1] How truly quiet are these motors compared to geared?

2] Does the regenerative braking function tend to seriously loosen the axle nuts?

3] How comparatively efficient in general is such a system if again run at 48V and 20A?

4] What top speed can be expected at 48V and 20A under ideal route conditions? [ And, yes, I've run the simulator but would like a little real world input. ]

Thanks in advance.

I have a HS3548 which is a higher speed wind than the 3540. I paired it up with Lyen's 18FET controller. For some unknown reason, my controller is not letting me go above 30A or so. But at 74V nominal Lipo, I am able to get around 40-43mph with some head wind at full throttle, medium battery, 2500KW power input, on flats. With no wind, I get around 43-45mph. with headwind same condition, I get around 37-40mph.

I also have a BMC V3 which is geared and the BMC motor accelerates faster, or at least I feel it accelerates faster than my HS3548. Note that bike is on 51.8V Lipo set at 30A limit. However during acceleration, I usually draw 50A or more on the BMC 18FET Controller.

Now to answer your questions:

1) The motor is dead silent during coasting just like the BMC, though the BMC does some coasting rolling noise. During acceleration, there is some pulsing sound, but hardly noticeable, especially with all the wind at 30+mph.

2) I don't know about this one since I don't use regen.

3) efficiency for my setup is around 40-57W/mil. That is average speed of 30-40mph.

4) Look at the simulator. I find it matches very well on what I truly get.

 

[Alan B]

My BMC V4C in 20" wheel on a bikeE is using about 18 to 28 watt hours per mile in rolling hills with some steep climbs. The two values are the different directions on this route. Average is about 23 watt hours per mile for the sum of both trips. I'm running 12S Lipoly at 20A so 1KW with the Lyen 12 FET controller which is working pretty well.