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

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.

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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.

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    43 Discussions


    Question 5 months ago on Step 6

    What is the answer you got for the question of using 36v battery for 24v motor?

    I took a 250 watts 24 volt go-bowen atv and a electric mini bike 1000 watts 36 volt. I took the motor off the mini bike and the control box and put it on the small atv the only thing I had to change was the back sprocket because the 1000 watt motor had a bigger sprocket than the atv motor had I had a sprocket and I centered it up on the sprocket that was on the atv and welded it and it worked perfect this thing will fly I weigh about 210 lbs. it pulls me good I did have to cut the frame just a little to fit the 3 batteries in it I turned one side ways and the other two laid straight in side by side. I am thinking about putting bigger tires on it


    Question 1 year ago

    Sorry that's 2 brushed motors


    Question 1 year ago on Step 7

    Can I dual connect 2/ 24 volt motors and. Use one controller. And get better performance.


    3 years ago

    I have a 500w 24v electric scooter, I'm using 2 12v 10ah ub12100-s batteries. I want to add a 3rd battery wired to a button mounted on the handlebars to use the extra power when I need to. My question is how would I go about wiring this and able to use the 24v constantly and able to use the button for 34v?

    1 reply

    12 years ago on Introduction

    Does increasing the voltage by 50 percent roughly double the power? For resistive circuits, it generally does---the power is proportional to the square of the voltage, so 3/2 the voltage gives 9/4 the watts. I'm not clear on inductance in electric motors, though. I'd think that if you saturate the flux capacity of the electromagnet cores, the excess power would be converted straight to heat. Does your motor get very hot? I'm wondering if there's a simple test you could do with your multimeters to tell when you're saturating the cores, and limit the power to what actually boosts speed, without wasting more as heat. (BTW, those meters look familiar... and really cheap... I have a yellow one and a red one from Harbor Freight, too.) Also, do you have any links to good instructions for de-sulfating the 12V sealed batteries? I have a couple that need help.

    13 replies

    Reply 12 years ago on Introduction

    A 36v controller from the 36V derelict scooter ;) I used a 24V rated motor - which is still healthy and spinning away :)


    Reply 12 years ago on Introduction

    Yep, it's a United Motor - it's been taking the 36V and hasn't had a problem yet. On paper, 36V would be bad for it. In reality, it's a hunk of copper, aluminum, steel and plastic. Remember, for this we care what it can do, not what it was intended to do ;) The wire inside is too big for the loads at 24V - so I'm not concerned about a fire or anything of that sort. Switching over to the 36V motor would yield a bit more speed, as it was wound for 36V, but that added complexity to this very short project.


    Reply 8 years ago on Introduction

    I tried this... adding 1 more battery to two scooters, one a Razor (250w motor) and the other a cheap Chinese made knock-off (200w motor), both being 24v original to 36v modified. I did not change the controller or anything else. I believe that the permanent magnet scooter motors are more robust than you would expect. Even the controllers rated at 24v running 36v do not get hot. The heavy Razor would go about 13 to 14mph max at 24v, with new SLA's running at 36v it will max out at 19mpg (gps tested). The Chinese knock off is lighter and the 200w motor reacts very well to the additional 12v and this scooter will top out around 22mph. In each scooter, I used 4 dpdt, Bosch relays to make a series/parallel switch, so when the relays are off, all three batteries are in series making 36v. When the relays are energized, The batteries are put in parallel and I can use a common 12v charger. There maybe some resistance in the relay contacts, but they are rated at 40amps at 12v, they too do not seem to mind the additional voltage. I do think think running 48v will fry something, but I have not tried that.


    Reply 2 years ago

    I have a razor e200 got it running on 250w24v motor & a 350w 24v motor on top . With standard 24v controller . It's the razor e200 version 36. Same controller as the E300. But when I start it in 36v it clicks on me . So I put a SPDT switch a ( on off on ) so as its moving I overvoult it to 36v 600w to 36v is like 1100w it's cool . But I charge it by 2 chargers 24v & a 12v u sed u out them in parallel snd charge them with one . Can I do that snd charge it off a 36v charger .


    Reply 4 years ago on Introduction

    can you please post the wiring schematic you used to mod up your 24v Razor to 36v using the stock motor and controller?? this is precisely what im looking to do and the idea of switching between parallel and series battery configuration is brilliiant


    Reply 2 years ago

    I made may razor e200 go from 24v to 36v by using a switch. If u try to start it on 36v it clicks. But run it on 24v then switch it to 36v and wow . Overvolting is fun. I have a 250w & 350w 24v & on 36v it flys


    Reply 4 years ago on Introduction

    check this vid out...would you recommend doing what this guy did? with either the original 24v configuratuion or the modded 36v plan with stock motor and controller?


    Reply 2 years ago

    Will not work . U will still get a clicking sound when trying to switch to 36v if that's what u r try to pull away with. I say with as u can pull away with 24v then switch a switch like I have when your moving to 36v to overvolt your 24v motors . Iv got a 250w 24v & a 350w 24v motor on my E200 on top of each other . It's flys on 36v . Overvoulting is cool& fun . But don't go more then 36v . U can take the limiter off & the voult strip behind u can put a wire down it then go to ground with it. Now that's how u take off the 24v relay that makes it click . I have not done it yet . I did the strip on the out side that's how I no it don't work . But this will . There is a man called TK on utube he Nos his stuff & shows u how to remove this . & more


    Reply 2 years ago

    Will not work and it will still make your controller click when going from 36v

    KaiPeylan rob_fed

    Reply 3 years ago

    How long did your battery upgrades last? Did anything burn up?