Brilliant Bikes (in the UK) sell a standard front wheel Brompton double walled rim for £28. Rims from Aliexpress are around the same price.

 

I would be confident that Brilliant Bikes will supply the geniune article, I would not be sure about a dealer on Aliexpress.

I managed to avoid buying from AliExpress for years, because nearly every time, I've searched for and found exactly the same item being sold on ebay, shipped from the UK for about the same price. Ebay have never refused me a refund, getting money back from AliExpress isn't easy, as I discovered recently. Trouble is, new products appear on AliExpress first.

Lightest Brompton I've ever seen: 7.1kg

 

https://www.eta.co.uk/2018/04/27/super-lightweight-brompton/

 

 

The same guy's 5.9kg folding bike; custom carbon parts:

 

https://www.eta.co.uk/2019/07/01/brompton-beater-the-worlds-lightest-folding-bicycle-weighs-under-6kg/

 

 

Edited May 20, 20232 yr by guerney

Early trials

 

Fairly often when ordering stuff on eBay if they do ‘Click and Collect’ I will have it delivered to the Argos in Sainsbury's which is about a 5.6km journey each way and about 80m in height of hills to climb, or around 260 feet of climbing in units that most of us grew up with.

 

To give eBrompton a trial, whilst waiting for supplies of 21700 5Ahr cells to turn up, I bought a Hoverboard battery, its 10S2P @ 4.4Ahr of allegedly Samsung 18650 cells and cost £50 delivered, it arrived the next day too. It weighs 965g.

 

 

eBrompton has not been upgraded to shopping trolley mode, so when I arrived at the store I carried the folded eBrompton, with battery still in bag by its built in handle (the saddle nose) to the Argos outlet at the back of the store. I carried eBrompton about 75m. Would not want to carry it much further, but I could manage it. So for local trips such as to small shops if your ebike does not have shopping trolley mode, its quicker to fold up the bike and carry it rather than lock it up outside. I was going to say the same would apply when visiting the doctor or dentist, but most people wont remember what they are.

 

The route home to shop only has a couple of hundred meters of main road, the rest is about 50:50 quiet residential streets and cycle paths. I mostly rode on assist level 2, but on a couple of the steep bits I put it up to level 5. The motor and battery seemed to cope with this well enough.

 

When I got back to my house, I waited 60 seconds and made a note of the battery volts, it was 36.2V. When I get some ‘better’ batteries I can use this 11km hilly route as a standard to compare batteries against. If I get a battery that would do the route twice, that would be enough for my needs, for longer trips just carry another battery.

Hi nice thread my standard Brompton with Swytch kit with modified battery mount and cadence sensor mount must weigh it to see the total weight

Neat conversion.

 

I have an old style Swytch conversion on a 3 speed Brompton, it weighs around 18kg.

 

Yours looks like the newer Swytch, if so is that the 5Ahr battery and how far do you get with it ?

used it a few times has throttle as well been getting around 18 miles to a full charge

Something worrying discovered whilst in Hospital

 

I was visiting someone in the local Hospital and rather than do the 20minute walk from home, I rode there on eBrompton. Of course I left the battery behind so this was a simulation of riding the bike as if the battery or electrics had failed. The cycle was OK.

 

I arrived at casualty, folded eBrompton up and carried it in. No-one said anything, folded it hardly looked like an eBike anyway.

 

It was whilst I was sitting down in the ward that I noticed a problem with folded eBrompton. The PAS sensor disk on the left side interferes and is bent outward by the Brompton rear frame triangle, when its folded underneath the bottom bracket, see picture below;

 

 

That issue probably explains why the Swytch kit uses a PAS disk that attaches to the crank arm and not the bottom bracket axle, see below;

 

 

Fortunately there looks to be plenty of room out on the right side, using the type of PAS sensor that fits between the frame and the bottom bracket securing sleeve.

 

 

So I removed the right crank and put the sensor in place. Spinning the PAS disk did make the front hub motor rotate the correct way, so I put the chainwheel back on.

 

The PAS disk was not as close to the PAS sensor as I would like, the gap was around 5.6mm.

 

 

With the chainwheel removed again I found that the sensor stopped working at around 6.5mm spacing, so its within 1mm of failing, not good. For potentially more reliable operation, I bent the sensor disk a bit and added a 2mm spacer to the bottom bracket mount to move the PAS disc out. With the chainwheel and crank back on it looks quite neat, works too.

 

 

Only annoying problem was that the cable on the right side PAS sensor was quite short, so there was a connector visible outside of the battery\controller bag.

 

I like to have spares to hand, so I now needed to buy another right side PAS sensor as a spare. I found an el-Cheapo one (£5), which had a long cable. Yes it had a JST-SM connector but it should be easy enough to wire a Julet to the end, see below.

 

 

What is maybe convenient about this sensor is that if the sensor part fails, you can easily access the single screw fixing it to the metal bracket and replace the sensor without removing the chainwheel and crank. I have had a PAS sensor fail on another eBike.

Edited June 3, 20232 yr by StuartsProjects

Portable repair stand

 

There is the problem that when out and about and you need to repair a puncture. Its easier, particularly if its the rear wheel to turn the bike over and prop it upside down on the ground. There is a problem with all bikes in that the stuff on the handlebar can get damaged, particularly in the case of an eBike which has a display to worry about. Break the display and the eBike goes no more.

 

I had seen the ‘Handlebar Jack’

 

https://www.handlebarjack.com/

 

Which is a pair of small tripods that you fit with elastics to each of the bar grips and then turn the bike over. You can buy them on eBay £40 and the pair is light at 90g. Neat idea.

 

However 90g is a lot to carry around all the time, so I had a think.

 

Expanded Polypropylene foam (EPP) is a foam I have used for making radio controlled planes. The foam is light and springy but stiff for the weight. It does not fall to bits like polystyrene. It sticks very well indeed with contact adhesive too.

 

I had a cut block about the right size so I cut a circular hole in it and then cut the block in half.

 

 

eBrompton is only around 12kg, so for a real test I placed the blocks on the handlebars of my much heavier eMountainBike, I held them in place with a bit of PVC tape.

 

 

I turned the bike over and it was quite stable and firm resting on the foam blocks with everything on the bars well clear of the ground.

 

 

Weight of the foam blocks, 6g plus 2g for the tape. Cost of foam, around £2.

Hi, enjoyed your very interesting build on your Brompton. Regarding the PAS sensor and the fitting possibilities. Have you considered fitting the Brompton bottom bracket torque sensor instead? .The part is quite expensive at £95 from SJS but I guess it would also give an improved "feel" from the electrical assistance. Is this possible or is the part too proprietary to the Brompton controller / system.?

The part is quite expensive at £95 from SJS but I guess it would also give an improved "feel" from the electrical assistance. Is this possible or is the part too proprietary to the Brompton controller / system.?

 

My understanding is that the KT contoller being used expects a 3 wire PAS only.

 

I have seen the Brompton torque sensor (5 wires) but assumed it was propriatry to the Brompton controller.

 

I am happy enough with the way the PAS responds and I already had an Aceoffix Titanium bottom bracket (lighter) so thats the one I used.

Edited June 6, 20232 yr by StuartsProjects

One needs a special controller to work with the SJS TS, it isn't compatible with a generic PAS /cadence type controller.

Taking control of charging

The 10S1P of Samsung 21700 50S 5Ahr is on order, so with a test and comparison to be made with super el-cheapo hover board batteries, it was time to take control of charging. I wanted to be able to more closely monitor the charging process and add a bit of extra safety too. Later on I wanted to be able to measure the amount of charge applied to a battery and to be able to measure the batteries Ahr capacity in a controlled way.

 

Monitoring the charge process

I wanted to be able to control the charge cut off voltage for three reasons;

 

First there are indications if you mostly charge to 41V (for a 10S battery) then you may extend battery life.

 

Second if your not going to use the battery for a while it can be a good idea to charge only to say 38V for storage.

 

Third, if you could set a charge cut off voltage of say, 42.5V, you would have some protection against a charger failure potentially causing a battery fire.

 

However most all eBike chargers have a fixed charge limit of close to 42V, they are not normally adjustable, which in itself is maybe is a good idea for safety reasons.

 

There is a low cost device (£8.50) that will monitor the battery voltage with settable low and high voltage limits. This device is the XH-M602. It has a mains relay which allows it to turn on or off a connected battery charger according to the set limits.

 

 

So if you set an upper limit of 42.5V and something went wrong with the charger then the XH-M602 will detect the over voltage and remove the mains power to the charger, thus maybe preventing a battery overcharge and\or fire. If you do only want to charge the battery to 41V, then just set that as the upper limit.

 

The XH-M602 is a bare PCB with mains connections and it would not be safe to use it on the bench uncased. So a simple box was needed.

 

Clip top food containers, the good ones, are fairly solid, easy to work as project boxes and cheap. I decided to use a 680ml one from Tesco.

 

The switched mains output is connected to a twin mains socket, one socket for the charger and another for a timer light, etc. I suggest that only those with experience of working with and building mains equipment attempt such a build.

 

The mains leads are fixed in place with grommets from TLC Electrical and there is a pair of shrouded multimeter style sockets to tap into the battery voltage. The matching plugs are shrouded, since using bare plugs would be a considerable hazard, all too easy to accidentality short something out and many many amps could flow from our battery.

 

The XH-M602 was mounted on hex threaded nylon pillars to bring the display and switches closer to the lid. The switches were extended outside of the box by gluing and heat shrinking some short rods to the top of the switches on the PCB. The assembled charger controller is shown below. Easy to secure the lid with self tapping screws if you wish.

 

 

I needed a lead set to go between the battery and the charger which would allow the charger controller to monitor the battery voltage. The shrouded multimeter plugs in the picture above go in the sockets on the charger controller. There is a fuse in-line with the battery positive. If you wanted to check the accuracy of the XH-M602 voltage display then the shrouded plugs used have a 4mm socket on them allowing you to daisy chain and plug in additional leads such as for a separate multimeter. The battery leads are on the bottom left and the charger connects to the anderson powerpole connectors on the bottom right.

 

I discovered a problem however, the Swytch battery\controller pack does not appear to connect the battery to the charge socket unless there is a voltage present on the socket from the charger. So the XH-M602 does not see a battery voltage and leaves the charger mains off. To correct this problem you need to force the charger to initially switch on so its output voltage then turns on the battery and the XH-M602 is happy.

 

The circuit of the XH-M602 looks straightforward there is a 12V relay switching the mains for the charger with one end of its coil connected to +12V and the other end grounded by an open drain or open collector transistor. So all we need is a push to make switch with one wire to the open drain or open collector transistor (or the anode of the diode across the relay coil) and the other end to circuit ground.

 

I made the change and the charger, if needed, can now be forced on at the beginning of the charge cycle, hold the button down for a few seconds, release it and the charger should now stay powered, assuming the battery is not equal or higher than the stop voltage.

 

The XH-M602 is a low cost option that allows you to take control of the charging process and you can charge your batteries to the voltage you choose as long as its within the chargers limits.

 

 

Edited June 12, 20232 yr by StuartsProjects

There is a low cost device (£8.50) that will monitor the battery voltage with settable low and high voltage limits. This device is the XH-M602. It has a mains relay which allows it to turn on or off a connected battery charger according to the set limits.

 

If a charger goes haywire for some reason, and starts providing higher than it's normal charging voltage - risking your house and all it contains - this could switch it off, if the upper limit is set slightly higher than the charger's normal output.

 

Delivery from (allegedly) within the UK for a few pennies more:

 

https://www.ebay.co.uk/itm/313913320302

If a charger goes haywire for some reason, and starts providing higher than it's normal charging voltage, this could switch it off, if the upper limit is set slightly higher than the charger's normal output.

 

Indeed so, from the post;

 

"if you could set a charge cut off voltage of say, 42.5V, you would have some protection against a charger failure potentially causing a battery fire."

Great project, but a complete waste of time and money. You cannot regularly under-charge a lithium battery that has a normal top-balancing BMS, especially on a 1P battery, where the higher cell current will knock it out of balance. If you wanted to under-charge, all you need is a 10S lithium charger that charges the cells individually through separate channels, or you could use two 6S lipo chargers with an adapter lead. In that case, you don't need a BMS.

 

Most normal 36v chargers are indeed adjustable if you can get them open. if you want to do a storage charge, you just put it on the charger until it reaches the voltage you want. The exact value isn't important as long as it's not full or empty.

 

When you use your system, before drawing any conclusions, you should check whether the balancing is kicking in at whatever voltage you choose to charge to. You can tell by putting your finger over the bleed resistors in the BMS. They become warm when dissipating the charge, and that's why measuring the charge energy isn't accurate, because at some point the bleed resistors open and the power goes out of your charger and heats the environment instead of charging the battery. That's without considering all the other losses.

 

Finally, 5Ah 21700s cost £6 each, so £60 for a 5Ah battery. How long do you expect to extend their life by to claw back the cost of all that special charger you made?

Finally, 5Ah 21700s cost £6 each, so £60 for a 5Ah battery.

 

Do you have a link, where do you get an eBike battery of 10S1P in 5Ahr 21700s for £60 ?

Do you have a link, where do you get an eBike battery of 10S1P in 5Ahr 21700s for £60 ?

https://eu.nkon.nl/samsung-inr21700-50s-5000mah-35a.html?gclid=CjwKCAjwhJukBhBPEiwAniIcNXkYMjGUiQ2d0ltBiU2DkHl8gaD_4uVuhdLQ3GpY66Wfqpi5OCSejhoC4sgQAvD_BwE

https://cellsupply.co.uk/product/samsung-50s-21700-battery/

 

You could have built three batteries for £15 each. So what if they only last for half as long. When the battery gets tired, just swap in the next cell-pack of 10. It's about as close to a free battery as you can get. there are also loads of people selling similar cells at similar prices taken out of crashes Teslas:

https://www.ebay.co.uk/itm/385589411664?_trkparms=amclksrc%3DITM%26aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D250629%26meid%3D3fb2d6d2865540a991028708e5d56050%26pid%3D101195%26rk%3D5%26rkt%3D12%26sd%3D155332751831%26itm%3D385589411664%26pmt%3D1%26noa%3D0%26pg%3D2047675%26algv%3DSimplAMLv11WebTrimmedV3MskuWithLambda85KnnRecallV1V4V6ItemNrtInQueryAndCassiniVisualRankerAndBertRecallAndPBoosterV3a%26brand%3DDyson&_trksid=p2047675.c101195.m1851&amdata=cksum%3A3855894116643fb2d6d2865540a991028708e5d56050%7Cenc%3AAQAIAAABUOF2C1v4PvLuUMt94LTx3USaOPJBiGrcV6%252Fms53nuTmrZ3dyQNOibl5UuvBUL5wYmcuhlieo3faZqx%252BhFc6Ti9XirkkCUJ2LfxVb%252B9nxabunfUYGsMpL1Y%252FxmkjPHNCqMgXo2ECai9wWaAOy6fJOFjQr5NbMX582L%252FNqyS36Il4nr6Vw2txUEGLkSPKNqxb8xgzVW6BhGj6yKBatquGFI4wS%252F8yTdf%252FuiE%252Bh7vfAh0XKK2FTOEM%252FaH5SJrji7qSnimhvXtRc%252F8Q5OXG4sq2kdFi%252BaXZCyDITUCteuTDLBNYlcFT8%252FqKOcHK7UuZ30cWk7NylSEG0LMD%252B3GdAGH0Ua9bGODfcB%252BIdwr5tnwY9OLlcD8QwRRpOkbTcWCryw167DX4aqha2hNv1XSyYJ058e4yHbkYbpJr%252Bcf58NXqZAqRw8o4pAeRBaaDkjA7vqlJilA%253D%253D%7Campid%3APL_CLK%7Cclp%3A2047675

Edited June 12, 20232 yr by saneagle

Not at all intersted in the price of individual cells.

 

Where can I buy an eBike battery consisting of 10S1P in 5Ahr 21700s for £60 ?

Edited June 12, 20232 yr by StuartsProjects

Not at all intersted in the price of individual cells.

 

Where can I buy an eBike battery consisting of 10S1P in 5Ahr 21700s for £60 ?

If you want to charge them to less than 42v, you need a battery without BMS.

Finally, 5Ah 21700s cost £6 each, so £60 for a 5Ah battery. How long do you expect to extend their life by to claw back the cost of all that special charger you made?

 

The cost of some 5Ah 21700s might well be £6 each, but then of course it has to be built with a BMS.

 

The cost of the 10S1P I ordered was £225, so slightly different to £60.

 

The 'special charger' cost maybe £25 to build.

https://www.ebay.co.uk/itm/385589411664?_trkparms=amclksrc%3DITM%26aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D250629%26meid%3D3fb2d6d2865540a991028708e5d56050%26pid%3D101195%26rk%3D5%26rkt%3D12%26sd%3D155332751831%26itm%3D385589411664%26pmt%3D1%26noa%3D0%26pg%3D2047675%26algv%3DSimplAMLv11WebTrimmedV3MskuWithLambda85KnnRecallV1V4V6ItemNrtInQueryAndCassiniVisualRankerAndBertRecallAndPBoosterV3a%26brand%3DDyson&_trksid=p2047675.c101195.m1851&amdata=cksum%3A3855894116643fb2d6d2865540a991028708e5d56050%7Cenc%3AAQAIAAABUOF2C1v4PvLuUMt94LTx3USaOPJBiGrcV6%252Fms53nuTmrZ3dyQNOibl5UuvBUL5wYmcuhlieo3faZqx%252BhFc6Ti9XirkkCUJ2LfxVb%252B9nxabunfUYGsMpL1Y%252FxmkjPHNCqMgXo2ECai9wWaAOy6fJOFjQr5NbMX582L%252FNqyS36Il4nr6Vw2txUEGLkSPKNqxb8xgzVW6BhGj6yKBatquGFI4wS%252F8yTdf%252FuiE%252Bh7vfAh0XKK2FTOEM%252FaH5SJrji7qSnimhvXtRc%252F8Q5OXG4sq2kdFi%252BaXZCyDITUCteuTDLBNYlcFT8%252FqKOcHK7UuZ30cWk7NylSEG0LMD%252B3GdAGH0Ua9bGODfcB%252BIdwr5tnwY9OLlcD8QwRRpOkbTcWCryw167DX4aqha2hNv1XSyYJ058e4yHbkYbpJr%252Bcf58NXqZAqRw8o4pAeRBaaDkjA7vqlJilA%253D%253D%7Campid%3APL_CLK%7Cclp%3A2047675

 

There is no possibility of me have a battery built from alledged used Dyson cells bought on eBay.

 

Far too risky in my view, although there may be some who consider the considerable cost savings worth the risk.

My 12s2p of Molicel p42a cost me < £100 to build, I prefer to build all mine so that I can use cells of my choice.

My 12s2p drinks bottle battery of HG2 cells was less < £80 I think.

A good arduino spot welder soon pays for it self.

A good arduino spot welder soon pays for it self.

 

Cost ?

 

Arduinos I understand .....................