The non-converted Brompton weighs around 8.4Kg.

 

Wow that's light! Their lightest weighs 7.45kg. Is yours a fixie? I hope you'll post pics of your bike and conversion.

36V 10S1P into alliexpress, and heck its amazing the bargains to be had.

 

You can get, for a mere £26.44, with free shipping, get an alleged 36V 30Ahr battery, what a bargain.

 

 

Post a link to the AliExp battery.

I doubt though it woul dbe a good buy even at £26 for your usage.

 

???

 

https://www.aliexpress.com/item/1005004968506548.html?spm=

Is yours a fixie? I hope you'll post pics of your bike and conversion.

 

Not a fixie, a 2 speed, but no mudguards or rear rack, so the same features as the 7.45Kg T-Line but with 2 gears and at around half the price. However, so popular is the Brompton that there are mods for just about everything and someone does make a 3 speed rear cog set that will fit on my standard rear Brompton wheel.

 

One of the biggest weight savings was to get rid of the 3 speed rear Sturmey hub gear and swap for a standard 2 speed rear wheel, a saving of 600g.

 

2 Speed is enough on an electric Brompton, for my use pattern, and I rarely change gear on the current 3 speed Swytch one anyway.

 

I will write it up, although its rideable at the mo I am waiting for the carbon handle bars (costing £12 and a weight saving of 132g) which will be a starting point for a conversion thread.

???

 

https://www.aliexpress.com/item/1005004968506548.html?spm=

 

Yep, thats the type.

 

There is a simular one that has 30000mAhr printed in big letters on the battery. I guess its a printing error though, and the m ought to be a u, 30000uAhr looks a more likely capacity.

 

 

Edited April 11, 20233 yr by StuartsProjects

Any of those you will be a numbskull to even consider buying and a retard if you think any one will work safely on an ebike.

Both examples will likely use very poor cells or dangerous ones.

 

A seller who claims 30000mah can't be trusted if they can't even get the spec right and 4400mah 18650 simply don't exist.

 

We saw what can happen with the E-rider episode and the 30ah £90 battery, it simply failed in short time with poor duff cells.

 

A decent 1s pack will be a min of £50 /£60 using decent cells, a decent cell for a 1s will need to be at least 20a rated .

 

 

The cells will be something like those aweful Ultrafires that will guarantee a fire with an ebike and which have proved to be very low quality with less then 1000mah per cell.

Edited April 11, 20233 yr by Nealh

Any of those you will be a numbskull to even consider buying and a retard if you think any one will work safely on an ebike.

Both examples will likely use very poor cells or dangerous ones.

 

Indeed so.

 

I was tempted for a microsecond or so to buy one just to see haw bad they really were, but could not thing of a safe way to try one in an eBike, even if you were in a quarry with nothing flamable around, you could still set fire to the bike.

 

But I bet people are buying and using them, if only for a short while, after all they are a bargain.................

Yep, thats the type.

 

There is a simular one that has 30000mAhr printed in big letters on the battery. I guess its a printing error though, and the m ought to be a u, 30000uAhr looks a more likely capacity.

 

 

[ATTACH type=full" alt="51075]51075[/ATTACH]

 

Does that even have a BMS? Looks like plain shrink wrapped cells.

 

In my very early days of messing about with ebikes, I made a 10S 1P pack from cells I had lying around while I was waiting for the pack I'd ordered to arrive. I dutifully put a BMS on it and connected it up the the bike. It worked perfectly for less than 100 m, then the BMS cut in as the voltage sagged below 30V. I was not very happy and I removed the BMS and connected it directly. I did about another 100m before smoke started coming off of some of the cells. I quickly cut the power and stood well back. It cooled down, but the shrink warp on several of the cells had melted and peeled off. If hadn't spotted the issue, it could have been nasty.

 

So that's what will happen with a badly constructed 10S 1P pack with cells that are poorly matched and not designed for 15 A current draw. If there is a BMS and it does it's job, you won't get far. No BMS or a faulty BMS and you are likely to end up with a bike fire.

For a light weight bike with 1s how far do you want to ride ?

12 - 15 miles if you are lucky using a quality 21700 cell.

 

Good call, the Samsung 21700 40T is 4Ahr and has a very high discharge current capability. Might be a way to go, 10S1P for light weight and local, 10S2P for long distance mode.

Yep, thats the type.

 

There is a simular one that has 30000mAhr printed in big letters on the battery. I guess its a printing error though, and the m ought to be a u, 30000uAhr looks a more likely capacity.

 

 

[ATTACH type=full" alt="51075]51075[/ATTACH]

 

 

My guess is what they have done is use 3000mAh cells, then there are 10 of them, so they came to the conclusion it must be 30000mAh

https://www.aliexpress.com/item/1005004968506548.html?spm=

 

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I could get one similar to the UK, £14 plus £6 shipping:

 

 

This is the claimed spec:

 

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Make sure you have the UK set as your location, it often defaults to Afganistan.

 

I could get one similar to the UK, £14 plus £6 shipping:

 

Amazing.

 

Someone could buy 10, put them in parallel, paying £140 for a '30Ahr' battery or is it 300Ahr ?

 

(I recommend you dont try this).

Amazing.

 

Someone would buy 10, put them in parallel, paying £140 for a '44Ahr' battery (dont try this).

 

 

The listings are different for the 4.4Ah and the 3Ah models, hence the difference in price, but yes, someone might try and put a lot of these in parallel, <£140 (as they do a bulk discount) would still be cheap for a 30Ah pack. Probably would need 10 Schottky diodes though to ensure some level of safety!

If you have a mini spot welder then one can make up a cell pack using quality cells like the 40t or p42a/p45b's . All rated for 25/30a and genuine high current cells, they still though need a 1s protection board for safety.

 

Problem is with buying 10 cells is the price at least a fiver a cell.

 

I have one of those cheap ultrafire cells , it cam with a torch I bought. The cell wrapper is an amazing one and indicates 9800mah which some unknowing gullible person would believe. The cell is amazing I charge it and the torch gives out amazing light and is super bright but after about 10- 15 mins use, it is as much use a chocolate fire guard.

I tested it from a lowly 3.15v and got about 810mah to a full charge, like all cheap over rated cells the chinese simply add a 0 to the mah rating to big them up. 980mah I likley the most it can ever see from 2.5v.

 

As with these AliExp bargains , if it looks to good a deal then it is and one shold pass GO without stopping.

I would never mess with the electrics on either my bike or any other, as I freely admit I just don't have the technical knowledge or expertise to do so. If anything needed doing I'd take it to a professional to do.

I would never mess with the electrics on either my bike or any other, as I freely admit I just don't have the technical knowledge or expertise to do so. If anything needed doing I'd take it to a professional to do.

 

Sage words, the problem is though that there are too many people who know enough to get in to a fight and are keen however don't have the requisite knowledge to do it safely.

 

I did my degree decades ago in E&E Eng, did nothing with it in life bar DIY however past 7 yrs have got back in to it Raspeberry PIs for 3D printer and Arduinos for with slot cars making start light gantrys, timing boxes and addressable LEDs for track calls etc. - so much fun!

 

However I would baulk at doing any maintenance on my 52V 17.5Ah LG Hailong as I just don't have the experience and one mistake could be end up being fatal, just like I wouldn't try and fix the mains electricity board in flat or resolder a leaking gas pipe ;-)