Heinkel EV

What are the Most Difficult EV Conversion Tasks?

Heinkel EV Swingarm
Early Mockup- Heinkel Kabine EV swingarm

Those EV conversions you see on Instagram and in magazines make it look easy. And it is easy- if all you do is write the check! Actually doing a conversion is more complicated and time consuming than I thought. As I close in on the completion of the build portion of the project, I wanted to share what have been the hardest parts and offer a little advice if you ever decide to do an ICE (EV-speak for “Internal Combustion Engine”) conversion.

Task 1: Where to put the batteries?

Heinkel EV Battery Layout
First Attempt- Heinkel Microcar EV Battery Layout

This applies universally to all EV conversions. Batteries take up a lot of space and planning where they go, then building a container for them is the most important task. You can’t have an EV without a battery, and you can’t have a battery without a safe place to put it! I made a cardboard mockup, then a wooden version and then a final wooden version before I had a battery housing that worked.

Task 2: Where to put the rest of the EV components?

Heinkel Kabine EV Electrical Components
Heinkel Kabine EV Electrical Components

Once I found a battery spot, there’s other components to consider as well (see the link here). These took up more space than I thought. Because I’m running high voltage (72v) the main wires are thick and need space to bend. You also can’t use regular 12v automotive components in the high voltage part of the electric system; these higher voltage components are larger and heavier, and not only require space but ventilation as well.

Task 3: Designing the drivetrain:

Heinkel EV Swingarm
Second Mockup of Heinkel Kabine EV swingarm

You would think using a hub motor would make the whole process much simpler. It did, but it was still complicated. I had to design a swingarm to accommodate the hub motor and work within the confines of the space I had (back to Task 1, where do you put the batteries). I also had to get the swingarm geometry to mimic the range of travel of the existing swingarm (answer is 70mm in case you are interested😊) and approximate the original Heinkel wheelbase version.

Task 4: Learning everything about EV’s:

I really knew nothing about EV’s before I started. Their relative lack of moving parts compare to an ICE vehicle belies the complexity of the design. I got an EdX certificate in EV Technology https://www.edx.org/course/electric-cars-technology. There’s lots to consider, everything from which battery chemistry to choose to the drive system the mounting and even which kind of motor (AC or DC) to use. Once I had a rudimentary understanding of those big picture concepts, I had to apply them to a 60+ year old microcar. I rethought my choices several times, and there’s still things I’d consider changing if I ever did a version 2.0 (no plans at the moment).

I learned a lot from the three other Heinkel EV’s. I’ll have another blog post on those soon.