For Sale DIY project folding ebike - Merc (Brompton clone) - 250W 36V (no battery)

daniel.weck

Esteemed Pedelecer
Aug 8, 2009
1,213
1
£350
(also advertised in Facebook marketplace)

This Brompton clone built by Merc has a frame made of aluminium. The rear wheel hub is a 3-speed Sturmey Archer. This model has the luggage rack with mini wheels, and the M-type handlebar.

The front wheel is cross-laced with a barely-used (low stress) Bafang / 8-Fun 250W 36V hub motor which delivers a ton of reliable torque (especially noticeable with the small 16" wheel!)
Low-mileage Schwalbe Marathon tyre.

The programmable ebike controller handles 10A, which is plenty of power for this application.

There is a brake cut off, and a pedal sensor. There is a 3-position power selector on the handle bar, as well as a rotary throttle control on the other side (which overrides the pedal sensor).

One of the spokes in the rear wheel snapped (nothing to do with the ebike conversion, it broke before that). The wheel works but of course it is not as safe as it should be.

Note that the 36V battery is not supplied, but I am selling parts separately for (very) keen DIY-ers ;) (i.e. cells and BMS)

Reason for selling: I built this as a fun backup for my main project: a Brompton with a 250W Tongxin (in practice, a less powerful but more fragile setup compared with the Bafang). I ended up riding the Brompton a lot, and it never failed ... so the spare Merc remained folded in my garage most all of the time. It is now time to let it go.

I took photos quickly to post this listing, and I didn't even take the time to clean the dust off the frame. I will of course give the bike a good wipe before selling :)

I tested the motor and its various controls, just before taking the pictures (using my 36V DIY e-Brompton battery)

Note that if you already own a "real" Brompton, you could use this Merc as a donor bike to DIY your very own e-Brompton (i.e. swap the widened fork + wheel). This is a reversible operation if you hold onto your original fork and wheel.

Collection only, Crowborough (East Sussex, South East England)
 

daniel.weck

Esteemed Pedelecer
Aug 8, 2009
1,213
1
...and if you are comfortable building battery packs, I also have this 36V LiFePO4 Battery Management System rated 40A (Li Ping BMS v2.5)

This is the BMS v2.5 from Li-Ping, which came with my LifePO4 battery pack (10Ah, 24 cells, 12s2p layout, each prismatic cell is 3.2v 5000mah).

This BMS is rated for 40A maximum continuous discharge current. It features the usual protection against over charge and discharge, etc. More importantly, this BMS automatically balances the cells during the charge phase.

I have the original pouch cells, but unfortunately two of them "died" (low voltage), thus why I decided to sell the BMS separately so it doesn't go to waste.

I also have the 36V charger dedicated to this BMS, with the original connectors. I will consider offers for this too :)

I will not ship the battery cells, but I will consider selling for cash on collection. This would be an interesting project, actually: reduce the capacity from 10Ah to 5Ah by keeping the best 12 cells out of the 24 (12S1P instead of 12S2P layout). Throw the 2 bad cells away, but keep the remaining 10 for backup or other projects ;)
 

daniel.weck

Esteemed Pedelecer
Aug 8, 2009
1,213
1
I created a separate listing for the BMS and battery cells (+ charger)
 

daniel.weck

Esteemed Pedelecer
Aug 8, 2009
1,213
1
Re-posting photos, sorry.
 

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