Introduction: How to Convert a 24V Scooter to 36V - Dirty Method

By
About: Engineer making renewable energy products for African entrepreneurs.

It's a quest for E-speed... And I don't mean a dot com bubble "E." These instructions are proof of concept for, hopefully, bigger plans.

Step 1: Source Parts

Two scooters were used for this project. Both of which were found deralict and to be thrown away at Standford University. Dumpster diving may, or may not, be illegal. But better to ask forgiveness later.

The first scooter has rusted away and is completely un-ridable. It is a 36V machine.
The second is a 24V model, with heavily sulfated battery packs. Ridable, if you can get it power

Charger: I picked up a battery charger from harbor freight for other projects -- it cost me $10

That's all that's really needed -- lets get to it.

Step 2: Gut Scooters

This is really a more careful operation that it sounds. You'll want to mark everything, to make sure you can put it back together at a later date.

Important things to mark on the motor controller

  • Motor
  • Battery
  • Power Switch
  • Charger
  • Brake Switch (to kill motor while braking)
  • Hall effect sensor (throttle) -- this has three wires B-R-Gr
  • Any other accessories (such as a horn or running lights)

Also, keep track of your connectors. From what I've seen in the 6 or so scooters I've come by, disassembled and hacked together - everyone uses the same set of connectors - but they don't always use the same connector for the same task.

Step 3: Charge Batteries

I used the 3 12 volt gel cells from the 36V scooter for this hack - the 24V sulfated pack will be desulfated at a later date. These need to be charged. I charged them on a 1.5A "smart" charger using a multimeter and an ammeter to monitor progress. This is a proof of concept, and a rather dirty hack -- so things are twisted and clamped together.

Step 4: Wire Up Good Scooter

Here is where it gets tricky... It's highly likely that your connectors will not match -- mine didn't. The best way to go about this is to start with one connector. See if both sides mate. If they do, more on.

If Not - check the other side of the connector on the other scooter. Then remove the pins from the connector and do a Frankenstein swap. The pins usually have a small tap inside - push it to the side with a small screw driver, then pull the wire/pin out.

Sometimes, there's no remedying it. In cases like these -- you can jam the pin on the wire into the connector, then secure with tape. Be sure they won't short inside the tape as these motor controllers are rather sensitive :/

You absolutely need to connect the following items

1. Hall Effect Throttle
2. Motor
3. Battery

For safety you should also connect the brake switch.

Step 5: The Power Switch

I couldn't get the pins out of my power switch -- nor did I want to as I'd need to move 4 different connectors around.

The power switch is open while off, and closed when on. My solution was to stick a metal screwdriver inside, short the pins and tape it on. Not elegant at all - but utility is the idea.

Step 6: Motor

This was a big question mark.

The 36V motor did in fact mate with the motor mount on the scooter. However, the shaft offset is different throwing the chain out of alignment.

Solution -- make an adapter plate....
Dirty Solution -- use the 24V spec'd motor

The big question was weather or not the 24V motor would handle the new voltage and amperage....

Step 7: Power on and Fly!

I used my ammeter between the batteries and the controller -- this way I could monitor draw. It also served as a handy power indicator. .01A draw means the controller is on (the switch circuit is closed).

When you wire everything together -- connect the battery second to last, and the power switch last. It's also probably a good idea to do a "dry run"-- without the motor connected to the rear wheel (VIA chain).

Before powering on, make sure all connections are tight -- and insulated. The last thing you want is to accidentally short something.

Once your dry run is successful -- load everything into the scooter. I taped on my ammeter so I could monitor current flow

Results? Yes.

It's faster -- but it was a little slow to accelerate. My front tire has a leak, that keeps getting bigger. So that didn't help. But truly, much faster than the 24V variant I was running before :D

Proof of concept:
1. 24V motor appear to take the extra strain - likely shortening their expected lifetime
2. Gel Cells aren't too sensitive to Charging at 1.5A (just make sure the temps stay low)
3. This can be done within a few hours (except charge time - you'll want a bit longer)

Yes, I've been bit by eFever... I've always liked it, it's just reaching critical mass methinks.