DIY electric Brompton: Finished.

[templehead]

I've been using one of the pair of old Bromptons I recently acquired to get up to the local train station with little success. The route is all uphill and tackled comfortably on my electric Dawes, but the Dawes is massive and not great for taking on trains. So I have decided to convert one of the Bromptons to run on sparks. The kit arrived from Aliexpress today and looks pretty good, except for them having 'upgraded' me to sensors for the brakes as opposed to the complete levers advertised. The sensors are for use on a modern Brompton, and won't fit mine so they'll have to be changed.

There were no instructions included, but the wiring looks pretty self-explanatory... the only thing I might resort to YouTube for is to see how the crank sensor thing works/should be fitted.

I've also ordered a little case for the controller, and a luggage mounting and L bracket for the front, as that's where the battery (also on its way) is going so it should still fold up OK. I just need a tyre and tube now, then the first job will be to swap the front wheels over. More soon...

 

[Kell]

Interested to see how you get on.

Was it significantly cheaper than the likes of Swytch?

 

[templehead]

Was it significantly cheaper than the likes of Swytch?

The only price I can find for the Swytch kit (they don't seem to be selling them at the moment) is £799 from a review in 2020. I paid a little under half that for the kit pictured, a 36V 30Ah battery, a box for the speed controller, luggage block and L bracket.

 

[Gunk]

Interested to see how you get on.

me too

 

[templehead]

A few more bits have arrived...

The luggage block and the shelf that's going to hold the battery, the little box for the controller (which I think is going to hang under the crossbar) and some velcro straps to keep the cables nice and tidy.

The battery comes with a mounting plate that it slides onto and locks to using the key. I'm going to screw the baseplate to the back of the shelf so the battery can be easily removed as required.

 

[ColinJ]

... a 36V 30Ah battery

That sounds unlikely to be its true capacity. That is 1,080 Wh which is about double the capacity of most large ebike batteries!

How big and heavy is it?!

 

[templehead]

That sounds unlikely to be its true capacity. That is 1,080 Wh which is about double the capacity of most large ebike batteries!

How big and heavy is it?!

Dimensions are 360x90x110mm, weight isn't stated. It's an Aliexpress one, so I factored in it being about a third of the claimed capacity, which will be plenty for what I want.

 

[ColinJ]

Dimensions are 360x90x110mm, weight isn't stated. It's an Aliexpress one, so I factored in it being about a third of the claimed capacity, which will be plenty for what I want.

View attachment 734973

That's what I was thinking... It would have to be 2 or 3 times that big to hold as much energy as they claimed.

I hope that it turns out to be a successful project!

 

[templehead]

That's what I was thinking... It would have to be 2 or 3 times that big to hold as much energy as they claimed.

Yeah, pretty much every rechargeable battery for sale on Aliexpress has its capacity comically overstated. I have some 18650s I bought from there for £1 a go that are labelled 9800mAh... they run my big torch brightly for a decent amount of time though, which is all I ask of them. You just have to apply a pinch of salt!

 

[templehead]

While the battery is on the slow boat, I thought I'd make a start by fitting the handlebar furniture; new brake levers, throttle and instrument panel. This came to an abrupt halt when I discovered, courtesy of my Lidl digital verniers, that the bars on this Brompton are 23.5mm diameter, and the opening on all the new Aliexpress bits is 23mm... the kit is advertised as being for a Brompton, but mine are so old that they could have had the bars changed? Or maybe they're just narrower on the newer ones?

Whatever, a bit of work with the Dremel will save the day... if only I hadn't lent the Dremel to my sister 😬

I will, of course, be raising this with the seller; with a bit of luck a partial refund will be winging its way to me...

Meanwhile, I'm off to retrieve my Dremel

 

[Regular.Cyclist]

Brave buying a battery from Aliexpress. If they are lying about capacity what else are they lying about? Where do you intend to charge it?

 

[templehead]

If they are lying about capacity what else are they lying about?

Probably no more or less than about 75% of the battery vendors out there. It'll be treated with the same levels of suspicion as all the Li-Ion batteries I own.

 

[templehead]

So, Dremel retrieved, I set about fitting the brake levers. With a bit of judicious grinding this went fine, although there were a couple of other considerations for anyone else thinking of trying this... first off, if your cables look like this:

then you'll need to cut off that plastic cover thing for them to fit in the new levers. Also, I found that the nipple was too fat for the slot in the lever here:

so if your cables are like mine, you'll need to give that a tickle with a file. The throttle control included in the kit can't be used, because it's too small to go onto the bars, and I feel sure that attempting to file it out would end in disaster, so I've ordered a different one that will hinge round the bars in the gap between the brake lever and the shifter on the RH bar.

And here are the results of today's labours in full (including the little instrument panel)...

 

[albion]

The only price I can find for the Swytch kit (they don't seem to be selling them at the moment) is £799 from a review in 2020. I paid a little under half that for the kit pictured, a 36V 30Ah battery, a box for the speed controller, luggage block and L bracket.

That is full price. The recent best offer was £299. Sign up for emails.

 

[templehead]

That is full price. The recent best offer was £299. Sign up for emails.

That seems cheap... does it include a battery?

EDIT: even if it does, apparently their standard battery is only good for 9 miles...