New Bafang Crank-Drives

[tahustvedt]

Yes, the spider, chainring cog and spacers are CNC-milled at home, and It's all held together with ten M4 bolts. I bet you could make a new chainring with that Litepro ring I linked to in my previous post using your drillpress and a bandsaw. They are available in different tooth counts as well. I use a super cheap bandsaw for my rough cutting of sheet aluminum.

 

[tahustvedt]

Instead of using the included throttle lever I decided to do something else. I managed to lure two thin wires under the bar tape by soldering the ends to a stiff brass wire and pulling it through. Then I soldered a 12,5 kOhm resistor in series with a microswitch and connected it to the 5V and throttle signal pins. The result is a hidden boost button behind the right brake lever. It's a bit awkwardly placed now, but it works fine. I will install a 1 mm thick microswitch under the rubber hood when I can find one for a completely hidden button. I used 12.5 k because that's what I had. I also tried 2.8 K and that didn't work.

There is a lot more power available by pressing this button than just by PAS.

 

[Racer_X]

Instead of using the included throttle lever I decided to do something else. I managed to lure two thin wires under the bar tape by soldering the ends to a stiff brass wire and pulling it through. Then I soldered a 12,5 kOhm resistor in series with a microswitch and connected it to the 5V and throttle signal pins. The result is a hidden boost button behind the right brake lever. It's a bit awkwardly placed now, but it works fine. I will install a 1 mm thick microswitch under the rubber hood when I can find one for a completely hidden button.
There is a lot more power available by pressing this button than just by PAS.

Nice, simple stealth solution!
Good job! I will have to try something similar. Thanks for sharing your technique!

 

[teslanv]

Gear Sensor review is here.

http://endless-sphere.com/forums/viewtopic.php?f=4&t=60963

It's a worthy addition to the BBS0x kits.

 

[Ken Taylor]

Brilliant bike. I plan to make a wooden frame some day.

Thanks for the kind feedback from twain, tomjasz and tahustvedt. Tahustvedt's battery box is nice but it doesn't look like bamboo. It must be a material manufactured from bamboo. I wonder if there is any potential for working with tahustvedt on wooden frames. There are a few contributors to The Lance and our wood carver can make almost any possible shape which I hope will be better explored in the next model.

We don't have CNC though and the high precision achievable with CNC machining would allow reduced wall thickness in some sections which would help in the quest for minimum weight.

 

[tahustvedt]

The battery box was made from a bamboo end grain kitchen cutting board.

 

[teslanv]

I am curious if anyone is running the BBS02 750W kit at 63V max (15S LiPo) ?

Or to ask the question differently, what is the highest voltage you have ran in the BBS02?

 

[Kepler]

Yes I do.

Max voltage you can use is 61.5V. Any higher and a HVC stops the drive operating. Other then that the drive works fine on 15S. Of course you no longer have LVC protection and the battery indicator shows full all the time.

Unless you have a really good reason to go 15S, i would suggest to give it a miss.

 

[pjgold]

Yes I do.

Max voltage you can use is 61.5V. Any higher and a HVC stops the drive operating. Other then that the drive works fine on 15S. Of course you no longer have LVC protection and the battery indicator shows full all the time.

Unless you have a really good reason to go 15S, i would suggest to give it a miss.

4 x Zippy flightmax 7s 5.8a would be my battery pick next time, although the frame mount pack is nice and easy.

 

[Kepler]

What are you doing for battery monitoring and LVC?

 

[teslanv]

GT Precision Watt meter.
http://www.amazon.com/gp/aw/d/B00C5...200_QL40&qid=1403583630&sr=8-2#ref=mp_s_a_1_2

 

[hadonf]

Hello folks!

First post here, but I've been through this whole thread for the last few months and finally made my choice on the BBS02 750w, along with a 11.6Ah battery.
Here is my build, I've choosen a road bike because the minimum distances I usually cover here in the country are at least 30 km.

For instance my commute to work is 43 km and still have to go back home at the end of the day!
The drive is doing really well indeed, and I have been able to return an average of 42 km/h on that commute trip.
It still need some refinements like a proper button instead of the thumb throttle that cannot be fitted to the handlebars, a gear change cut off switch and surely a wattmeter.

However I'm still confused , because I was aware of the BBS02 750w short according to em3ev.com, but i wanted one quite quickly, at least before the winter returns, so I asked conhismotor and they said they were able to send me the unit and claimed they have some in stock.
It took a bit more than one month since the initial order to arrive at my door, especially because of the battery according to them..
And this is what I came up with:

Is it some kind of temporary version before Bafang put in production the new 25A controller? which is by the way well over 750W.
And the other surprising thing with that unit, is the 46T provided chain plate, instead the 48T usually provided.
But even though, the unit is really astonishing, able to climb insane grade without peddaling or going over 55km/h on flats without my legs helping, so it clearly seems that the speed limiter isn't working. On the 46T/12T ratio the max no load speed is 63km/h, isn't it supposed to cut way before?
So what exactly is that controller, a tamed down version of the 25A, will I be able to upgrade it with the 25A version in the future?

Anyway I'm about to order a wattmeter and a USB to TTL adapter to sort all this, and give some updates.

Cheers and thank you again for all these unvaluable infos!

 

[Spacey]

After a very long absence from the forum whilst I left my job to start my company I thought I would jump in this thread briefly....

I have UK stock arriving within a week arriving at our depot of the new 9 Fet V2 750W Bafang mid drive kit. UK delivery is free and Europe delivery at cost.

Loving these little motors, I can also program them for any power/speed limits (or lack of) acceleration curves etc. Will be making a larger post about my business later today in its own thread

www.custom-ebikes.com

 

[tomjasz]

GT Precision Watt meter.
http://www.amazon.com/gp/aw/d/B00C5...200_QL40&qid=1403583630&sr=8-2#ref=mp_s_a_1_2

Would you share were on your system you installed it?

Tom

 

[Aushiker]

GT Precision Watt meter.
http://www.amazon.com/gp/aw/d/B00C5...200_QL40&qid=1403583630&sr=8-2#ref=mp_s_a_1_2

Would you share were on your system you installed it?

There is some good information over the ditch on installing one of these.

Thread source at Pedelecs. See also this thread and this thread.

Andrew

 

[tomjasz]

Thank you!

All signed up for my electronics class, old dog and new tricks, very excited! I enjoyed the read on soldering!

 

[teslanv]

GT Precision Watt meter.
http://www.amazon.com/gp/aw/d/B00C5...200_QL40&qid=1403583630&sr=8-2#ref=mp_s_a_1_2

Would you share were on your system you installed it?

Tom

I just installed it in line with my battery leads. (Battery + & - into Watt-meter then Watt-meter + & - to Bafang Drive.) It is mounted on my handle bar stem just below my Head unit.

It will tell me Instantaneous Volts, Watts & Amps, Minimum Volts, Maximum Amps as well as Accumulated Amp-Hours & Watt-Hours.
It's the next best thing to a cycle analyst, and much easier to install with the BBS02 kit.

 

[tahustvedt]

There's a risk of damaging the motor controller if the wires between the battery and controller are extended. If the battery wires are extended then extra capacitors should probably be added to the wires near the controller.

 

[Racer_X]

As long as you use proper gauge wire, it is no problem.

There's a risk of damaging the motor controller if the wires between the battery and controller are extended. If the battery wires are extended then extra capacitors should probably be added to the wires near the controller.

 

[Electric Junk]

What are the peak watts according to your watt meters?

 

[tahustvedt]

As long as you use proper gauge wire, it is no problem.

Well, I disagree. Using thicker wire will not help. It's not a resistance problem, it's an inductance problem. The damage happens gradually over time. Here's a good reference with explanations: http://www.rcgroups.com/forums/showthread.php?t=952523

As long as they are DC brushless controllers (not sinusoidal).

 

[Spacey]

This was always a problem when using those meters, the extra length of cable (many times longer than normal) used to run from the battery to the power meter then all the way back to the controller.

Thank goodness for the Cycle Analyst, if you could take the LCD part of the power meter and mount that on the handlebars with the rest of it next to the controller that would work.....but a lot of work involved I should think.

 

[Racer_X]

As long as you use proper gauge wire, it is no problem.

Well, I disagree. Using thicker wire will not help. It's not a resistance problem, it's an inductance problem. The damage happens gradually over time. Here's a good reference with explanations: http://www.rcgroups.com/forums/showthread.php?t=952523

As long as they are DC brushless controllers (not sinusoidal).

if you could take the LCD part of the power meter and mount that on the handlebars with the rest of it next to the controller that would work.....but a lot of work involved I should think.

Well I guess what i meant to say is that the gauge does not matter if you do it correctly.
Here is a way to wire a wattmeter remotely and as spacey says it is a hassle.

http://endless-sphere.com/forums/viewtopic.php?f=2&t=21976#p320027

Now lets get back to Bafang Crank-drives

 

[arclarke]

Hello folks!

First post here, but I've been through this whole thread for the last few months and finally made my choice on the BBS02 750w, along with a 11.6Ah battery.
Here is my build, I've choosen a road bike because the minimum distances I usually cover here in the country are at least 30 km.

For instance my commute to work is 43 km and still have to go back home at the end of the day!
The drive is doing really well indeed, and I have been able to return an average of 42 km/h on that commute trip.

Hi - I've been thinking of the BBS02 for the same sort of journeys, but wasn't sure that a 11.6Ah battery was big enough. I'd been thinking of motorising a cargo bike as a general purpose e-vehicle, but of course normally ride a more roady bike for 40km (a cyclo cross frame with touring tyres) and average 24km/h on that journey - so still in two minds about which bike to motorise. Are you having to be careful with the battery use? 42 km/h is nice and fast.

Also, when I saw the lack of 750W motors I was told I would need at least a 6P battery to provide enough current and the 4P battery like yours should be limited to 20A at most. But it sounds like your motor at 20A is fast enough anyway.

Alan

 

[hadonf]

Hi Arclarke,

I wanted the battery to be a good mix between capacity and weight. It seems that this 11.6 is exactly what I needed, I'm always keeping in mind battery conservation when riding, so I'm not hammering the throttle the whole time, and i'm also pushing quite hard on the pedals.
To give you an idea, after that big hour of riding at 40/45km/h the battery voltage is around 46.4V and everything is barely warm not to say fresh for the battery. Unfortunately I don't have any measurement device onboard for now.
I also went to a round trip in my hilly countryside and returned with a 112km trip, averaging nearly 35km/h and took me a bit more than 3h15min, the whole thing was with a 1500+ pos ascend in total, no stops. The battery was 44.2V at the end.
So it definitely depends on how hard you are on the throttle and how much you assist the motor. Err, wait a minute! Isn't the motor supposed to assist you?.. :lol: