My Mofa electric: How I used DIY to convert a regular bike to an e-bike

Though the next logical step was to hunt for an engine to get this one running, I was a bit reluctant to get into a restoration project.

BHPian ilangop recently shared this with other enthusiasts.

Hi folks. Been a long time since I started a new thread. In this era of migration towards electric mobility, I just wanted to share an interesting DIY project I undertook in the last 6 months. Through Olx, I was able to grab a Mofa frame, mudguard and fork with a handlebar alone for Rs. 4,000. I had no idea what I wanted to do with it when I brought the frame home.

Though the next logical step was to hunt for an engine to get this one running, I was a bit reluctant to get into a restoration project. I thought, why not try making an e-bike with this frame? Did some quick calculations, browsed the net and finalised the specs. I wanted the Mofa usable for at least 2 hours of riding. Load capacity could be similar to a bicycle. As such, the vehicle construction allows only one person to commute. Cost - as less as possible.

Somewhere at the beginning of this year, I took the plunge, placed the order for an e-bike motor and controller kit. For Rs. 12,000 I got a hub motor with disc brakes, brake levers with switches, accelerator with key switch module and battery level indicator, and the motor controller. It took about a month of searching to find a person interested in setting up the motor onto the rim of an XL Super. With some adaptation to the frame, the motor with the rim was mounted to the frame.

Likewise, some minor improvisations were made to install an XL Super front wheel assembly. Along with this, a speedometer from a TVS 50 moped was also installed. The vehicle has done 200+ km so far. It gives a range of roughly 60 km per charge. I will share some details about the battery and electricals in the upcoming posts.

The motor and controller together was a 600W, 48V system. The number of spokes in the hub motor perfectly matched the rim of the XL Super. I had to hunt for a spokes expert to install the hub motor onto the rim. You see, we are in the era of alloy wheels and tubeless tyres. So this skill is also getting rarer.

A rough calculation of power = voltage x current gives 600/48 = 12.5A. This means a 48V battery with a capacity of 12.5Ah would roughly last for 1 hour. But this being the peak load requirement, we would notice that the current consumption under normal running scenarios would not exceed 10A.

Though the max rpm capability of the motor was not available, I assumed that it would be able to touch speeds up to 35 km/h. For higher top speed, a larger tyre and rim would be needed. However, due to space constraints and as the XL rim was already available, I went ahead with that combo.

Battery pack sizing:

To cater to the peak current requirement for 1 hour (assuming we would like to run the e-bike for 1 hour after a full charge), the system would need a 12.5Ah battery back. Considering the space and budget constraints, I settled down for a 10Ah pack (13S-1P) with BMS for current limiting and cell balancing. I purchased it online. It reached me after a week as it is not allowed to ship battery packs by air. I used the engine area for mounting the battery over a steel tray on the left-hand side. Parallelly, I purchased a Lithium-ion battery charger. Put the battery pack for charge with some loose temporary wiring and did the maiden ride on our terrace.

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