Just got one of these this week. http://www.7dayshop.com/products/7dayshop-waterproof-rechargeable-intelligent-rear-indicator-bike-light-WH2-CM-002 . Rechargeable, auto shuts off after 3 minutes of the bike standing still, comes on automatically at night and has indicators as well! Pretty good...
This would do the same, just have it configured for 10s 36v (42v) https://bmsbattery.com/ebike-charger-ev-charger/24-alloy-shell-120w-lifepo4-li-ion-lead-acid-battery-ebike-charger-ecitypower-charger.html
Just an update on how the cells are performing. Very well indeed. I made a 6p10s pack for my A2B Metro and very little sag, great power delivery, nothing to complain about. Build was a PITA though, serves me right for wanting to recreate the original rear pack. Frame pack to rebuild next!!
Thats how the original pack looks. I'm rebuilding by soldering to the tabs of my new cells in the same configuration 10s 6p. I'm using thick 32A solid copper wire to connect the cells together.
I designed it myself as there's no pedal assist on the gen 1 or any kind of dashboard. Next job is to move from simple pedal assist to building an actual torque sensor. i.e. if you're having to push harder the throttle will ramp up to meet you so to speak. Still working out the how to detect though!
I'm currently building a new rear pack from cells from Tumich on here. See the for sale section. Samsung 29e in a 6p10s config. I'll let you know how I get on. Could do with an empty rear case if anyone's got one!,
If you look below the gap about an inch, there's the transistor! not sure of this design, but checking all the other one they sell, they all have a missing (or relocated) cell one transistor.