Friday, August 24, 2012

DIY ebike conversion with MPIII Goldenmotor

I bought a  used  Merida Cruise bicycle and converted it to an electric bicycle with the Magic Pie 3 from Goldenmotor. This is how I did it and a test of the finished ebike.

My initial picture after assembling the Magic Pie 3 and performing my first test run. 
I try to bike to work using my regular bike as often as possible, and then showering when getting there. But some days I have to meet customers, with no option to shower. Then there is also the case when I wake up and just do not feel like pedaling at all. In both these cases I often end up taking the car. My goal now is to keep the car parked, and enjoy life with this amazing ebike.

Since we have many hills in Norway I wanted the bike to have a powerful motor. I found the 1000W 48V MagicPie 3 (MP3) from  GoldenMotor in China. I like the simplicity of the front wheel motor, but decided to go for the rear wheel motor. It gives a better grip and perhaps better handling. I also liked the idea that the controller was integrated in the hub motor. The performance can be tuned by connecting the MP3 to a PC with a special USB cable. A legal limited power motor or a full power bike? You decide by programming.

After about two weeks I got the delivery. There are some special bike tools needed to take off the 6 gear cassette so I went to the local bike shop and got some assistance.
Cassette before adding washer to MPIII Goldenmotor
Cassette before adding washer
Cassette with needed washer for MPIII rear wheel
Cassette with needed washer
MPIII can be used with most 3 to 6 gear bikes. Mine is 6. Take the cassette off the old rear wheel and move it to the MPIII rear wheel. First we forgot the washer and ended up with a cassette that did not free wheel. It was not easy to get off again! So make sure you remember to add a washer that will make the cassette free wheel.
Showing mounting order of washer and cassette on to the MP3 wheel
Mounting the washer , then the cassette
After this I fitted the rear wheel with the motor to my bike and tightened the nuts on each side firmly.The first week I used a twist throttle for adjusting the power to the motor. I did not like it much as I found it too easy to twist. It was also tricky to avoid twisting while breaking. So I changed to a thumb throttle that I like much better.

So on the right side I now have the thumb throttle. It moves nicely with my thumb. I also have the rear hand break from Goldenmotor which includes a switch  that detects when breaking. This signals to the controller inside the MPIII to cut off the motor and activate the regen breaking. The factory setting in my controller was set to 50% regen which gives a good portion of extra breaking power. I have adjusted this to 15% to minimize the risk of slipping. The hand break also activates the original mechanical rear breaks of the bike.

I moved my gear shift from right to left side. That is why the numbers are upside down, but it works just fine. I also decided to not install the hand break with regen breaking on this side. I have kept the original front wheel hand break here, then I can use this for very light breaking with out the powerful regen breaking cutting in. The red button is cruise control. Use the  thumb throttle to achieve desired speed, then hit the red button to maintain that speed. Power to the motor is cut off when hitting the red button again or when breaking with my rear hand break.

The power connector to the battery broke when I was on my first bike trip in March 2013. I fell on my bike when making a turn. I was just barely moving, but the black power connector broke when the bike hit the road. This was at +2C, so it was rather cold. The plastic housing just broke up in many pieces. Seems to be a cold weather problem with this. I replaced it with a original Anderson housing SB50 P/N 992G2-BK. It can be bought several places, such as where it has P/N: 879-992G2-BK
The + and - metal pins from Golden Motor snaps right in to this housing, so it is easy to replace. No resoldering required. If you do cold weather biking it might be good to get a spare now.

Twice I had a flat before understanding the problem. The last time it was obvious. The pressure of the tire was a bit low and when breaking hard the tire and inner tube must have moved slightly. Inside the rim there was a very sharp aluminum edge that corresponded to the razor sharp cut in the inner tube.  In the picture to the left I have sanded it down. Please check for this before putting your tire on the Golden Motor rim.

The performance of the MPIII can be adjusted by connecting a USB cable to a PC and running the free PD-280 software. This is the setting I got when pushing the "factory setting" and then "get config".

GoldenMotor PD-280 software for tuning the MagicPie 3
Factory setting on my MPIII rear wheel motor controller.

I have not been able to find a good guide on how to use this program, so I give you my experience with it in my post Programming the MPIII electric bike controller


ScotiStavanger said...

Nice one Svein. I should have a MP3 in Stavanger in a week or so and look forward to hearing your experiences. Sounds good so far.

Svein* said...

Hi, Good to see that someone in oil city Stavanger is interested in electrical bikes :-) Very encouraging. I have almost forgot what color my car has, I am now using my ebike everywhere...

Unknown said...

I actually got to try this bike a few days ago and I love it! It can pull you up some pretty steep hills without a hitch.

ScotiStavanger said...

Just got back and put the kit on my old bike.......excellent result. Very well pleased.

Anonymous said...

What about waterproof and snowproof. Is the controller still working?
Volker Oslo

Svein* said...

My first controller lasted only about a week. Two of the MOSFETs inside were short circuited. Possibly a combination of wires with broken insulation, a very rainy day, and me giving full power while the bike was going backwards. I got a new controller for free (except shipping) that I replaced myself. This one has worked just fine. No problems, but I have been more careful not driving in more water than necessary, and also making sure not to give full power when not moving. I have also reduced the max power in the software settings.

ScotiStavanger said...

I have had trouble with two Anderson plugs just disintegrating, most probably because of the cold as my bike is kept in a shed. When the weather stops freezing I will try the aftermarket Anderson plugs I bought from eBay and see how long they last for. Apart from that no trouble at all with the bike.

Anonymous said...

Great post! I also fell in the same trap regarding the washer.

John A Davis said...

So that is what the washer is for. I guess I didn't need it haha.
I found out the lock on the Lipo battery is a Honda lock and you can get the keys duplicated at any key shop. It is great to find out what connector is used. I have bookmarked this page. I can get 30mph out of the box on flat on my dual suspension mt bike.

Anonymous said...

Very interesting to read about the golden motor.
I have been thinking about buying one myself.
Are you still using it ,is it still working.
Where did you buy yours from?
Would you recommend it or would you choose something else today?

Erik- Gothenburg

Svein* said...

Hi Erik,

I have 4000 km on this bike now. It does not like rainy weather. Once my kids let it outside in the rain one weekend, and I had to leave it in the sun for to days before it started to work again. The bearings are probably getting a bit worn too, judging from the increased noise of the motor. I bought mine direct from China I would only recommend it to someone with some electrical and mechanical knowledge. But it is very powerful, and get you going at the speed you like.

Anonymous said...

Thanks much Svein; I got my MP3 here at home from a Canadian distributer; Strong hint to anyone wanting to provide a domestic service/sales for GMotor products. Great blog, in particular, I appreciated the well presented information on setting up the software and the controller parameters. Happy Riding.

Gary Salo said...

Hi, I just stumbled across this post. Nice job. If anyone needs any assistance we have a ton of information, videos, parts and accessories at