Chinese 125cc + Honda IMA motor

Starting a conversion of a Chinese 125

Main Components are,
Direct Bikes 125cc Enduro
Two 48V 60Ah 2.8kWh 13s20p 18650 server backup battery packs.
Two 2kW Eltek Flatpack2 48V battery chargers.
Honda IMA IPU motor controler
Honda IMA flywheel motor, approx 20hp

I'm working to a very limited budget so almost all parts are used and some even come from the scrap pile.

The battery packs are very well built so I'm going to keep them as they are unless it is simply not possible to mount them sensibly. I'm hoping the batteries are actually good and give a fair proportion of their marked 2.8kWh (5.6kWh total). The batteries will be in series making a 96V 26s20p pack which leaves limited options for BMS systems. I've been experimenting with the diyBMS system https://github.com/stuartpittaway/diyBMSv4 which is really intended for power wall applications but is expandable and fully open source which I like. As the batteries will be in parallel and producing around 100V I will also have to be more careful with weather protection and insulation so will probably make an aluminium housing for the battery pack and power electronics.

I'm intending to use the Honda IMA power unit + motor with a Field Oriented Control FOC module / code developed by Johannes Hubner and Damien Maguire over at https://openinverter.org/forum/ which is also an open source project.

The biggest task at the moment is to make up some end plates for the motor as it comes without them.

As the chargers are capable of charging at 4kW which on a 5.6kWh battery is in the realms of fast charging so the end goal is to also have a Type 2 EV charge socket so I can travel further than the return range will allow and use roadside charge points.

Might be worth adding the budget so far is...
£75 Donor bike with log book (3 years and 8 months old!)
£300 Batteries
£100 Chargers
£50 Honda IMA power unit
£40 Honda IMA motor
Total £565

I'd like to get it running and on the road for less than £800 which leaves me with about £235 for all the other bits + maintenance to get it through a MOT test and on the road.

That will be a very interesting budget build :thumb:
Especially using the Honda IMA motor. Good luck and enjoy building, I'll be following your updates on this.

Me too
I guess that is low voltage for that motor and controller?

Yea, kind of, the original nominal voltage is 144V and the nominal pack voltage I have is 96V which is 2/3 of its original spec. But despite this it should produce the same torque up to the max RPM so it's a matter of final drive gear ratio.

I can always rewind it of it's if it's wildly underpowered or similar but I wont know that until I've finished it.

What does the motor rotor look like? I though it was part of the engine flywheel.

Yea it is part of the flywheel assembly so I'll have to make a shaft and end plates. I have a small hobby workshop and lathe so it's within my grasp and I enjoy a bit of that sort of thing one and a while.
My hobby is both making things and riding motorcycles so the engineering side of things is as much a hobby to me as just assembling parts or going for a blast in the country.


It's some sort of IPM Embedded Permanent Magnet rotor that has a resolver sensor on it.


Covered in tape to help keep the swarf and debris out.


The resolver.

Mouse said:

Yea, kind of, the original nominal voltage is 144V and the nominal pack voltage I have is 96V which is 2/3 of its original spec. But despite this it should produce the same torque up to the max RPM so it's a matter of final drive gear ratio.

I can always rewind it of it's if it's wildly underpowered or similar but I wont know that until I've finished it.

Click to expand...

Oh, I see. I though it would be in the 400v range like other ev:s, interesting.
What kind of phase amps do you think you can get out of the controller?

Where did you pick up the batteries from?

j bjork said:

What kind of phase amps do you think you can get out of the controller?

Click to expand...

The power IGBT module in the Honda IMA unit are rated at something like 300A, the batteries are rated at 220A max discharge so I think the phase amps to the motor can go right up to the limit if I push it. Although I'll not be operating it right up at the limit when it's in use to make everything last longer.
Just bought a second stator in case I burn the first one up experimenting. :wink:

Shazzy said:

Where did you pick up the batteries from?

Click to expand...

A one-off and badly worded ebay ad from someone who just wanted them gone for a reasonable price after finding them unsuitable for his off-grid needs. The seller was also hopeful to pass them on to someone who was going to do something useful with them which happened and as we chatted about mad projects when I picked them up as he not only lived off grid but also on a boat.
I've tried looking them up but cant find anything on the internet about them at all from the info on the manufacturer label. Other than that they're 18650 cells and I'm not intending breaking the case apart just to see who made them.

Mouse said:

I'm intending to use the Honda IMA power unit + motor with a Field Oriented Control FOC module / code developed by Johannes Hubner and Damien Maguire over at https://openinverter.org/forum/ which is also an open source project.

Click to expand...

When you're done getting the controller built/setup, I'd be interested to compare with this project
https://endless-sphere.com/forums/viewtopic.php?f=30&t=105711
once I complete at least one of them.

amberwolf said:

When you're done getting the controller built/setup, I'd be interested to compare with this project

Click to expand...

Oh yea I'll be sure to do that. I'd also like to see the comparison between projects and techniques for re-appropriating Hybrid power inverters.