Cheap Brompton Conversion Kit?

[shemozzle999]

I have been following the thread where d8veh is helping a member spec a new build.

He has found a new supplier Greenbikekit.

I had a look around the site and they are offering what looks to be an end of line 24v kit for a 16" wheel including a 24v,10aH frog battery, which maybe could fit a Brompton. It is important to select the 328rpm version the other options are personal preference.

It works out at $362.67 ( approx £230 ) including the cheapest Fedex shipping.
You would also incur maybe £65 import/courier fees, so total cost around £295.

You would need to get the front fork stretched to 100mm.

Not leading edge tech, but a cheap first conversion.

I offer no guarantees that this would fit, no doubt it will need some tweaking.

edit:

They also accept Paypal as a means of payment.

You will need to check with them that the motor is for use with v-brakes and whether it is sensorless or hall.

http://www.greenbikekit.com/index.php/24v-250w-gbk100f-electric-bicycle-kit-with-frog-battery.html

 

[cwah]

The kit is almost good, except that the rim for 16" is probably not the right size.

Check with them if they provide a 349mm rim size or if there is any way they can lace such a rim for you.

Most probably you'll have to find a rim in UK and ask a professional to lace it for you (catsnapper do it for a very good price with good quality)

 

[Deleted member 4366]

The 36v bottle battery kit is only £15 dearer at £245 and I've never had to pay more than £30 for any kits because they always under-state the value, so my estimate is £275.

 

[patpatbut]

Hi guyz, I was the one having the first build post.

Sorry for hijacking your post. I do have a brompton hanging around as well and I want to do the conversion for my second project.

what is the different between bafang SWXK5 and GBK-100F motor?
What is sensorless or hall motor?

thanks guys
Pat

 

[Deleted member 4366]

SWXK5 can handle a bit more power. GBK-100F (believe the same as Cute Q100) is quieter and smoother and a bit lighter.

Using hall sensors in the motor improves the controller timing, so you get a smoother start and a slight efficiency gain. The downside is that the solder joints on the halls can fail due to vibration or they get shorted when water gets in. It seems that problems with them are not so frequently reported as they were a few years ago, so I guess production processes and quality controls have improved. Personally, I have sensors in all my motors and I've never had a problem. The controllers that BMSBattery and Greenbikekit sell can switch between sensor and sensorless modes, so it makes sense to get a sensor motor if you have a choice, and if a hall fails in the future, you just pull the connector off and the controller will switch to sensorless mode.

Timing in sensorless controllers has also improved as the electronics gets developed further, so there's not as much difference as before.

 

[shemozzle999]

Hi patpatbut,

The Bafang SWXK5 motor they sell is rated 201rpm, suitable for 26" diameter wheels, you would need the 285rpm version for a Brompton.

Brushless motors can be either sensorless with only 3 phase wires to drive the motor or Hall sensored which have an extra 5 wires to which sense the rotation and speed of the motor.

Hall sensored motors are smoother in operation but could be less reliable because of all the extra wiring.

cwah - good point - awaiting clarification email from supplier.

 

[patpatbut]

thanks guys.

In that case, which kits is better for the brompton conversion? 24v or 36v one from greenbikekit?

Regards
Pat

 

[jerrysimon]

Pat I am a big fan of Tongxin motors for Bromptons if you want to keep it light. If you want raw power then a Bafang is probably better.

24v will draw more current and require more substantial wiring.

Whilst I agree this is a great deal, fitting a 100mm wide motors into Brompton 75mm wide front forks requires quite a big stretch. Also these more powerful motors will probably require a torque arm.

You may be interested in my Brompton build threads

Super light Goldant motor conversion

Tongxin Nano conversion

Regards

Jerry

 

[jerrysimon]

Ps

You may be interested in my Brompton build threads

Super light Goldant motor conversion

Tongxin Nano conversion

Regards

Jerry

 

[shemozzle999]

Not good news - I just had an email reply from Ms Alice at Greenbikekit - looks like a no-go situation.


Dear Shemozzle,

1. Just checked for you, for the motor you need, we are now out of stock.

2. Our rim is different.

3. The max capacity for our frog type battery is 10AH.

 

[patpatbut]

Pat I am a big fan of Tongxin motors for Bromptons if you want to keep it light. If you want raw power then a Bafang is probably better.

24v will draw more current and require more substantial wiring.

Whilst I agree this is a great deal, fitting a 100mm wide motors into Brompton 75mm wide front forks requires quite a big stretch. Also these more powerful motors will probably require a torque arm.

You may be interested in my Brompton build threads

Super light Goldant motor conversion

Tongxin Nano conversion

Regards

Jerry

Hi Jerry,

Thanks for your advice! Can you tell me how to source those components?

Is any company supplying Tongxin motor kit with brompton?

Thanks.
Pat

 

[patpatbut]

Not good news - I just had an email reply from Ms Alice at Greenbikekit - looks like a no-go situation.


Dear Shemozzle,

1. Just checked for you, for the motor you need, we are now out of stock.

2. Our rim is different.

3. The max capacity for our frog type battery is 10AH.

Oh well. What options do I have for the similar setup then?

thanks

 

[jerrysimon]

All the links for suppliers have been posted before.

Basically you have a choice to buy a ready made kit £700-800 incl battery or source the parts direct from China for a DIY conversion for about 1/3 the cost. Direct from China you will need to be able to specify exactly what you want and have patience whilst they prepare your order and ship it i.e. could take 4-8 weeks. There are obviously different warranty and backup considerations to consider too. For the DIY option the best thing is to buy two of everything, which is still the cheaper option.

Kits try here

Home page

Freedom E-Bikes - Home

DIY try here

http://www.keyde.com/

Motor-OutRider Eshop - EBike Kit Supplier-Complete Electric Bike Conversion System




Regards

Jerry

 

[patpatbut]

Thanks jerry

I have checked your DIY job and you are brilliant! I am not electric engineer and I want to DIY

for my purpose I need to travel 20 miles each way. Ideally, it could be run at about 20 mph (at least 15mph)

Would Tongxin motor do this job well? If I use Bafang motor, would I be able to fold the brompton still?

It would be nice if you can advise which Tongxin motor should I get.

Thanks in advance
Pat

 

[jerrysimon]

For your requirements you would probably be better off with a Bafang or a Cute motor which would need to be over volted if you want to run at 20mph.

The wider 100mm motors do effect the fold as even the narrower 80mm Tongxins do as well. I guess you could still use a Tongxin but again would have to over volt it to achieve 20mph. A Tongxin run at stock voltage will achieve about 14mph unassisted on the flat though I always pedal.

Will your commute be very hilly ?

I would recommend the standard Tongxin Nano narrow 80mm wide motor for your application if you want to go down that route. Note also the Tongxin run very free when not in use, is one of the lightest and certainly the quietest when running.

IMHO for front wheel builds the narrow 80mm wide Tongxins offers the best option for the Brompton. As stated though its not a power house and is really meant to assist you up to 15mph.

Regards

Jerry

 

[patpatbut]

Thanks. Jerry

My commute route is not very hilly but it does some hills to climb.

I probably follow your advice to go for the tongxin motor nano. Can you tell me where to buy? Is it 36v with 27xRPM?

By the way, my brompton is m3r and what controller should I get 4 it?

Many thanks
Pat

 

[jerrysimon]

Pat email sales@h9.com.cn and tell them what you want. The contact I dealt with was cici.

They provide a stock controller that goes with it plus you will need to tell them if you want throttle, pedelec or both.

You need a narrow width (80mm) 36v, 260RPM, for V brakes model. Stock they come drilled with 36h but I think they will drill them 28h for you if you request it. This enables you to then use the stock Brompton rims with all the advantages detailed in my threads.

Regards

Jerry

 

[patpatbut]

Thanks. Jerry.

I have emailed to see what she says.

I have looked via the website but they do not mention the name Tongxin motor. Is this the right one?

Hangzhou outrider technology Co.,Ltd.

Btw, can I choose higher RPM (let'sa say 328) to improve the speed? as my commute route is pretty flat and the speed is my main concern.

thanks.
Pat

 

[jhruk]

Don’t forget the Cute Q85 motor is also available in 83mm width. Not as silent as the Tongxin but about the same size and weight and is 328rpm, so slightly faster. I’ve been very pleased with mine in a 20” wheeled Dahon.

You’d need a 36 hole 349 rim for a Brompton as I think the motor is only available in 36 hole.

The KU63 or KU65 controllers work well with it.

 

[cwah]

Jerry and other that have experience on it, I have been wondering about the difference between the power output between the small geared motors available:
- Tongxin goldan - 1.4kg: 200W continuous max
- Tongxin standard - 2.3kg: 350W continuous max
- Cute 100 - 2.1kg : 350W continuous max
- Bafang SWXU - 1.9kg : 300W continuous max


I've put these max rating number almost randomly, can anyone can confirm or revise these numbers?