Left side
LocationWarsaw, Mazowieckie Poland map
Vehicle Magnum 16' frame bicycle
My old bicycle, bit too small for me, but that's what I had
MotorMY MY1016 250W Permanent Magnet DC
Motor taken from Chinese electric scooter
Drivetrain18 speed chain drive, what can you expect from MTB? Power from engine is transmitted directly on rear wheel using 53mm rubber covered roller.
Custom build - simple three relays switching batteries between series and parallel. Throttle control: one (on)-off-(on) switch attached to brake handle operated with one finger. 12V for starting, 24V for full speed.
Batteries2 other 17Ah, 12.00 Volt, Lead-Acid, Gel
Two different 17Ah lead acid batteries, one having around 12Ah left, second one about 6Ah. Free!
Recently tested with 22Ah GreenSaver batteries taken from my UPS to show this bike on EV meet in Poland :)
System Voltage24 Volts
Charger BSL 12/6
"Stef-Pol" 6A car battery charger. Charging with batteries connected parallel, initial current 4A, 0,5-1A when fully charged (200mA taken by two relays)
InstrumentationNone. Voltmeter for weaker battery will be used.
Top Speed15 MPH (24 KPH)
7mph at 12V mode
Acceleration12V mode - poor acceleration
24V mode - great acceleration
Range5 Miles ( 8 Kilometers)
about 4 miles of 24V range, then you have to switch between 12V and 24V to equalize battery voltages. Probably you can go as far as 6-7 miles on that but 12V speed is bit too low. Simply use your muscle power when in 12V mode to go around 10 mph with minimal effort.
Should do about 25 with GreenSavers :)
Watt Hours/Mile30 Wh/Mile
Estimated from battery capacity and range
EV Miles
Current:20 Miles (32 Kilometers)
Seating Capacity1 adult
Curb Weight60 Pounds (27 Kilograms)
20 lbs batteries, 30 lbs bike 10 lbs motor with support. Weights are estimated.
Conversion Time3 days?
Conversion CostMotor: One beer, say 2$
Bike: Alredy had one
Batteries: Free
Fuse: 5$
Relays, wires: 8$
Roller: 10$ + 3$ shipping
Switch: 1$
Other parts: 5$
TOTAL: 34$ yay!
The idea was to build electric bike from parts I already had, or could get as cheap as possible. It's the simplest EV bike you can build: power transmitted by roller onto rear wheel, no controller (three relays used to switch batteries series-parallel with automatic 32A fuse are bit too simple to call it "controller"), no welding, only roller was made by other EV guy.

As for now it is almost finished - Needs some final tweaks, batteries and "controller" will end up in a bag for example.

This EV was build only for fun and to get some practice - I have some plans for something bigger but everything depends on money I (don't) have ;)

As for now (2012) bike is unused since batteries has died completly. Also, maximum speed of 15mph is bit too low to justify having an electric bike - Maybe 36V would be enough?

Bike got temporary ressurected in 2014 as I've reassembled it and fed with UPS batteries taken from my UPS that I use at home. It has ben driven few kilometers at EV meet and city of Zyrardow and shoveled back into storage. It was nice to see this project bike running again :)

code by jerry