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

Picture of How to Convert  a 24V scooter to 36V - Dirty Method
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

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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

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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

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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.
drcrash7 years ago
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.
gmanstl drcrash7 years ago
See Anybody use a desulfator to "restore" old SLAs?
Increasing the voltage by 50 percent will probably smoke your controller before it even gets to the motor.
What motor and controller ar you using?
trebuchet03 (author)  gmanstl7 years ago
A 36v controller from the 36V derelict scooter ;) I used a 24V rated motor - which is still healthy and spinning away :)
K, the motor may take over 24 Volt, but not 36 Volt. Is it a Unite Motor?
trebuchet03 (author)  gmanstl7 years ago
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.
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.

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?

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

Derin6 years ago
how do u dispose the cells
DIY Dave Derin4 years ago
Take them back to the place where you bought the new batteries. I think they are legally required to dispose of them.
Sandisk1duo6 years ago
how would you fix the batteries?
12V Sandisk1duo5 years ago
basically you use a Desulfator (there is one on instructables!) which sends 1ms long 50v pulses.
amando966 years ago
i broke my scootrer's headtube aswell, but fixed it...
ReCreate6 years ago
those batteries look like they need to be cleaned or exchanged for new ones
trebuchet03 (author)  ReCreate6 years ago
Naw, like many things - it's what's on the inside that counts ;)
My friend and I are going to be converting his older-model Razor E300 to a higher voltage. I'm thinking we could get a new controller and a 48 volt battery pack, and probably a new motor. The batteries will still have to fit in the existing cavity, so they'll each have to be half the size, making the scooter have a much shorter range (oh well). I have a Zivan NG-1 48 volt charger from me and my dad's electric bike conversion. Any advice? Thanks
candle3607 years ago
can somone help me find a 32v scooter with charger, I need it to fix my bro's electric chopper, I just want it to go faster, his has no charger, about 50 bucks to replace it... so I'm just looking for the gutted parts, and I can do the rest, because my bro's chopper only went about 20mph when it worked, and with a 32v, I looked it up, will tow more and may go faster...
newkiraj7 years ago
One of my friends and I took a Razor E100 Scooter, and ordered some rather huge NIHM's online. It will do 40 mph w/ his 250 lb dad riding it. WOO HOO!!!!
hey I was just wondering 4 one of my other scooters, could I take a 12 V. , and a switch and just hack those right to the motor just skipping the controller? If so, could it damage it at all? Im not sure about the motor's ratings, but its another E100
trebuchet03 (author)  newkiraj7 years ago
You would lack control -- in that case, you'd be either all go or nothing. Which, on a scooter, can be a bit dangerous (from a control standpoint). Being able to slowly get up to speed ("slow" being relative to immediately all on) is in fact a safety feature on two wheeled vehicles ;)
i might rethink doing that... maybe a potentiometer instead of a switch?
or any type of variable switch for that matter
Okay, I did it today, I think it might fry the motor eventually, because the original controller is toast, the throttle is toast, and it caught fire. But, now that I put in new EVERYTHING it will go about 25 - 30 MPH -- a lot faster than the original 8 MPH! xD hope it dosent start on fire again!!