Andis FlitzerThe A sideCase study100 km/hTesting batteriesCooling gridContacted cellsfinished battery packsThe B side
LocationLucerne, Lucerne Switzerland map
Web/EmailWebPage email image
Vehicle1981 Yamaha RS 125 DX
MotorGolden Motors HPM-10KW fan cooled Brushless DC
Very good performance so far. Unfortunately, the
manufacturer did not provide detailed
information about their power measurements which
would be needed for declaring the 30 minutes
maximum power.
DrivetrainChain Drive
ControllerKelly KEB72121E, 24V-72V, 200A
Runs well, easy to set up. Very good acceleration. It's a little bit noisy on low revs, but who cares ;-)
Batteries72.00 Volt, Lithium-Polymer
DIY made of "Graphene Lithium Ion Polymer" cells
from Shenzhen WESTART Technology Co. Ltd. 40
cells, 3.6V, 20Ah, 10C continuous discharge. The
total pack is 2p20s, 2.88kWh and water tight.
Water cooling built in but not used. Hardly ever reaches 45°C.
System Voltage72 Volts
Charger 2x 84V 3.4A
Two XieTong C300, quality budget chargers from
China. On board, 2x300W, they fit nicely under
the old tank. I would not recommend them for EMC reasons.
DC/DC Converter Delta B70SR12424A
12.4V, 300W, water resistant IP67, small and
powerful. But I would not recommend it for EMC reasons.
Top Speed68 MPH (109 KPH)
With a sprocket ratio of 12/45
Acceleration3.5 seconds for 0 - 50 km/h (30 miles)
10 seconds for 0 - 100 km/h (60 miles)
I haven't seen a quicker 125 two stroke motorbike :-)
Range40 Miles (64 Kilometers)
On hilly curvy roads, with max speed of 80 km/h.
50 km is never a problem, I've done up to 76 km.
Watt Hours/Mile46 Wh/Mile
Average over the last 1000 km.
EV Miles
Start:20,525 Miles (33,024 Kilometers)
Current:22,944 Miles (36,916 Kilometers)
Total:2,419 Miles (3,892 Kilometers)
    As of 11/26/2023
Seating Capacity2 adults (155 kg payload)
Curb Weight265 Pounds (120 Kilograms)
Only 10 kg more than the original motorbike.
Tires2.75x18 and 3.0x18
Conversion Time5 years. Started in November 2015, finished in
July 2021.
Conversion CostOver 8000$, I stopped counting.
Plus 4500$ for electric safety tests, EMC and
MOT (required in Switzerland).
The project has given me a lot of fun and a lot to learn. I’m very
pleased with the outcome. The motorbike is really fun to ride, nimble
and light :-)
- Figuring out how to pack the batteries into that little space took me a lot of time.
- Also figuring out the regulations to get it road legal was not easy. In Switzerland electric safety and EMC needs to be tested from
an accredited test lab.
- After the first controller (Kelly KLS7250D) overheated, I replaced it with the KEB72121E and added active cooling with a fan.
- The external charger is very useful for longer trips. With the extra 1kW power (1.6kW total) I can “fast” charge within 1.5 hours.
Things I will improve:
- The LCD SOC display is hard to read in day light. I want to use the old rev gauge to display the battery voltage.
Watch my YouTube playlist for more details and impressions:

code by jerry