Views on 2 brompton choices

[spanos]

I'm in two minds and going for the forums opinions. Please bear with the precie!

Electrifying a m3l brompton with dynamo setup (factory installed)

So it's a front motor and losing the dynamo sadly. At least the loss of of the dynamo hub will slightly offset the weight of the motor

Weight is key for me as I do have e carry my bike up and down stairs, around Hotels etc. Ive a totally of 8 miles each way on different days as part of a bi weekly commute from south coast to peterborough.

I will build my own small battery with a daly bms. Probably using 5.2ah 27100 cells. 10s1p

Trying to choose between a q70 kit from woosh(minus battery)

Or going my own way using a funky little tubular controller which would fit very nicely behind on behind the fork (fold still works ive checked). In this case I'd use a tbk-74ad motor.

Price wise i think it comes about abiut the same price when all is said and done.

This is the controller https://www.topbikekit.com/10s13s-36v48v15a-yg-kt-6mosfets-sine-wave-controller-kt-tubular-controller-p-1039.html?zenid=nvvn4pd1kg18cs4r8mgkcb3u81

Thoughts ?

 

[matthewslack]

eBrompton Build

Why build an eBrompton ? The Brompton is a good bike for shopping or commuting and short range leisure trips. The neatness and compactness of the fold is a compelling advantage, you wont have trouble taking it on public transport or storing it in a corner etc. Fitted with a decent set of ‘easy’...

www.pedelecs.co.uk

 

[spanos]

eBrompton Build

Why build an eBrompton ? The Brompton is a good bike for shopping or commuting and short range leisure trips. The neatness and compactness of the fold is a compelling advantage, you wont have trouble taking it on public transport or storing it in a corner etc. Fitted with a decent set of ‘easy’...

www.pedelecs.co.uk

Thanks I did see that but he used a different motor from either that I'm proposing and different controller.

I appreciate he has reduced the weight in many other areas. I don't propose that as budget doesn't allow for that level of fettling

I guess I'm asking for views on the motors and the tubular contoller then

 

[matthewslack]

Shame there isn't a frame tube that controller could be hidden in, with a neat way to do the cables.

 

[spanos]

Shame there isn't a frame tube that controller could be hidden in, with a neat way to do the cables.

It'd fit but I'd have to drill an exit route and that doesn't appeal at all !

 

[saneagle]

I'm in two minds and going for the forums opinions. Please bear with the precie!

Electrifying a m3l brompton with dynamo setup (factory installed)

So it's a front motor and losing the dynamo sadly. At least the loss of of the dynamo hub will slightly offset the weight of the motor

Weight is key for me as I do have e carry my bike up and down stairs, around Hotels etc. Ive a totally of 8 miles each way on different days as part of a bi weekly commute from south coast to peterborough.

I will build my own small battery with a daly bms. Probably using 5.2ah 27100 cells. 10s1p

Trying to choose between a q70 kit from woosh(minus battery)

Or going my own way using a funky little tubular controller which would fit very nicely behind on behind the fork (fold still works ive checked). In this case I'd use a tbk-74ad motor.

Price wise i think it comes about abiut the same price when all is said and done.

This is the controller https://www.topbikekit.com/10s13s-36v48v15a-yg-kt-6mosfets-sine-wave-controller-kt-tubular-controller-p-1039.html?zenid=nvvn4pd1kg18cs4r8mgkcb3u81

Thoughts ?

Firstly, I wouldn't recommend a 10cell battery unless you use the larger 21700 cells or similar. The sag on 18650s is too much and they won't live long under that stress. Even 20 cells is pushing it.

Secondly, it doesn't make any sense to use power from the battery to work a motor to propel the bike to work the dynamo to make power for the lights, when you can power the lights directly from the battery. You need to sort out your thinking. Dynamo energy isn't free. It comes from work either done by yourself and/or the motor. In other words, you have to pedal harder. Normally, the aim of an ebike is to use battery energy to make it easier to pedal.

 

[harrys]

I've built two 13S-1P with P45B's, 4.5AH cells. Both tested out at 150WH with a 3A load. Range on my 20" folder with an AKM100 hub was about 18 miles.

Even with 5AH cells, I think a 16 mile round trip with a 10S will be optimistic.

 

[spanos]

Firstly, I wouldn't recommend a 10cell battery unless you use the larger 21700 cells or similar. The sag on 18650s is too much and they won't live long under that stress. Even 20 cells is pushing it.

Secondly, it doesn't make any sense to use power from the battery to work a motor to propel the bike to work the dynamo to make power for the lights, when you can power the lights directly from the battery. You need to sort out your thinking. Dynamo energy isn't free. It comes from work either done by yourself and/or the motor. In other words, you have to pedal harder. Normally, the aim of an ebike is to use battery energy to make it easier to pedal.

Hi saneagle

Thanks but you misread/misunderstand my post. I will be using 5.3ah 21700 cells with 30a rating. Sag no issue on 12a controller

I've no plans at all do anything like you say with a dynamo. I said I have a factory fitted dynamo hub so when I lose the wheel that contains it the weight penalty will be a tad less when adding in a motor hub.

My thinking doesn't need sorting out,though i think your reading might !

 

[spanos]

I've built two 13S-1P with P45B's, 4.5AH cells. Both tested out at 150WH with a 3A load. Range on my 20" folder with an AKM100 hub was about 18 miles.

Even with 5AH cells, I think a 16 mile round trip with a 10S will be optimistic.

Thanks , that's helpful. Luckily my commute is 8 miles each way but with an overnight hotel stay. Easy to charge

 

[matthewslack]

Look forward to hearing about your build and results.

 

[saneagle]

Hi saneagle

Thanks but you misread/misunderstand my post. I will be using 5.3ah 21700 cells with 30a rating. Sag no issue on 12a controller

I've no plans at all do anything like you say with a dynamo. I said I have a factory fitted dynamo hub so when I lose the wheel that contains it the weight penalty will be a tad less when adding in a motor hub.

My thinking doesn't need sorting out,though i think your reading might !

You said, "So it's a front motor and losing the dynamo sadly". That implies that you regret the loss of the dynamo.

I never said that you had any plans of what to do with it. I was merely pointing out the physics of how it works so that you can make the correct choice and avoid being sad by losing it, when you realise that it's a liability rather than an asset for an electric bike.

You clearly need help with pedalling, otherwise you wouldn't be fitting a motor. The motor and battery will give you assistance, and also eliminate the drag from the dynamo when the lights are on, so you get a double whammy. Therefore, the correct thinking should be, "So it's a front motor and losing the dynamo, thankfully".

 

[Peter.Bridge]

I did a front hub conversion a to a 20" wheeled Dahon clone (with 74mm fork size). The motor I used was a TBK-74AD (which I think is a rebadged AKM-75). I used the Woosh 36V 10Ah bag battery with a KT 15A controller. Depending on what assist level I use, I get between 40-50 miles range (which is more than I was expecting)

KT level 2 = 20% of maximum current = 0.2*15= 3 amps - so just over 3 hours of assist at level 2 with a 10Ah battery

(KT level 1 =13% = 0.13*15= 1.95 amps - so 5 hours of assist !)

The motor was 1.6kg and the bag battery was 1.8kg which increased the weight of the bike from around 12kg (including mudgards and pannier rack) to around 16kg. I don't know what weight your battery will be, but is it worth considering a bag battery like the Woosh one for the extra range ?

eta - I stuck the KT controller in the battery bag - was quite neat

 

[spanos]

You said, "So it's a front motor and losing the dynamo sadly". That implies that you regret the loss of the dynamo.

I never said that you had any plans of what to do with it. I was merely pointing out the physics of how it works so that you can make the correct choice and avoid being sad by losing it, when you realise that it's a liability rather than an asset for an electric bike.

You clearly need help with pedalling, otherwise you wouldn't be fitting a motor. The motor and battery will give you assistance, and also eliminate the drag from the dynamo when the lights are on, so you get a double whammy. Therefore, the correct thinking should be, "So it's a front motor and losing the dynamo, thankfully".

I think the phrase you were looking for was oh yes, sorry I misread or misunderstood. Rather than ignoring the cell point which I hadn't made and then trying to needlessly hack around the dynamo point

Its just oddly aggressive and simply odd behaviour to me and 'm reminded why I stopped coming here.

I shall happily crawl back to seaside from whence I came and just carry on riding !

Cheers
Kirstin

 

[spanos]

I did a front hub conversion a to a 20" wheeled Dahon clone (with 74mm fork size). The motor I used was a TBK-74AD (which I think is a rebadged AKM-75). I used the Woosh 36V 10Ah bag battery with a KT 15A controller. Depending on what assist level I use, I get between 40-50 miles range (which is more than I was expecting) The motor was 1.6kg and the bag battery was 1.8kg which increased the weight of the bike from around 12kg (including mudgards and pannier rack) to around 16kg. I don't know what weight your battery will be, but is it worth considering a bag battery like the Woosh one for the extra range ?

eta - I stuck the KT controller in the battery bag - was quite neatView attachment 62009

Thanks, that's very helpful too

Especially the rebadging, I didn't know that

 

[spanos]

Look forward to hearing about your build and results.

That's kind but I'll bow out now

I've decided I'm not going to risk the unknown controller especially as 12a. Going to go with woosh kit so nothing to be learned for the forum there I'm afraid. It's ook like the dahon peter shows

 

[Ghost1951]

I think the phrase you were looking for was oh yes, sorry I misread or misunderstood. Rather than ignoring the cell point which I hadn't made and then trying to needlessly hack around the dynamo point

Its just oddly aggressive and simply odd behaviour to me and 'm reminded why I stopped coming here.

I shall happily crawl back to seaside from whence I came and just carry on riding !

Cheers
Kirstin

Please do let us know how you get on with that project. I for one (and I expect others now and in the future) will want to do a Brompton conversion. I was also interested in your battery making idea.

On the relationships thing - don't take it seriously. Saneagle is a very generous person and he gives a great deal of good advice - if he is at times irascible it is a small fault. Honestly - take no notice of that. No one else does.

 

[Nealh]

Nice to hear you are still going well Kirstin, hope life is good for you , the wife and Four (probably ) not so little ones now.
The Daly BMS has been a bit hit and miss for me , not sure if they have improved reliability or no of late.
I had one drain a 48v battery PF cells to 0v (during one calender month) and one failed on my HG2 bottle battery over night, I caught th HG2 one and replaced it with a Be Much Smarter brand BMS.

 

[Nealh]

Spanos aka Kirstin had been along time poster on the forum well before covid days and is very well versed in battery tech and bike builds .
Those who remember will know that Swizzbee #1 came to me via Kirstin.

As to the battery a small/light 10 cell will work, Moli P45A or P45B would be top of my list.
Hub wise there is the Bafang G370 but is dearer then ther AKM.

 

[Bikes4two]

Please do let us know how you get on with that project.

Yes to that and although I'm not looking at a Brompton for myself, it's always interesting to see what others do.

When I run my carbon framed road bike (similar weight to a steel Brompton I think, (14-15Kg?) on a 10s1p (Molicell M50LT a 5000mAh 21700) on PAS=1 (KT controller) I get around 30 miles range. The same battery on a much heavier bike (23Kg?), maybe 20 miles at a push.

And of course there are now 21700 offerings of a bit more than 5000mAh albeit at quite low maximum continuous current but if you're a 'low 'e' asistance' rider that is likely not a problem.

On the relationships thing - don't take it seriously. Saneagle is a very generous person and he gives a great deal of good advice

True enough

- if he is at times irascible it is a small fault. Honestly - take no notice of that. No one else does.

Now that made me chuckle.

 

[spanos]

Nice to hear you are still going well Kirstin, hope life is good for you , the wife and Four (probably ) not so little ones now.
The Daly BMS has been a bit hit and miss for me , not sure if they have improved reliability or no of late.
I had one drain a 48v battery PF cells to 0v (during one calender month) and one failed on my HG2 bottle battery over night, I caught th HG2 one and replaced it with a Be Much Smarter brand BMS.

Oh, I've never had an issue with daly. Quite the opposite . I've used 3 (4 inc this build) , no issues and been running for years. The oldest pack is a good 6 years old which i gave to a friend amd he uses regularly still.

However a quick check online shows a pretty ropey reputation so i guess I've been lucky and will pay close attention to this new pack in early days. Thanks for the tip

And wife and four kids are all well. Though my eldest is now taller than me!