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Older Razor E100 replacing obsolete controller

I've got a version 1.0 E100 and the controller is no longer available.  I've bought a controller and throttle for a newer version and am wondering if anyone can provide a diagram of how this should be connected.  The parts I have bought are:

controller: SPD-24250

throttle: THR-35WG

Thank you for requesting this Razor E100 version 1 throttle and controller conversion wiring diagram. I have started working on it, and should have it finished in a couple of days. I will post it here as soon as it is completed.

Thanks.  Looking forward to it!

Here is the conversion wiring diagram for the Razor E100 version 1 electric scooter using a SPD-24250 controller and THR-35 throttle.

I also attached a PDF copy of this wiring diagram it can be easily printed.

Please let me know if you have any questions.


Sorry for the delay but I finally had time with the kids to try out these new parts along with the diagram.  The two scooters are working again!  Thanks again!  I did have a bit of an issue with the wiring on the switch as I assumed the switch on the drawing was oriented the same way as on the scooter with the off on the botton and the on at the top which resulted in me wiring it backwards with the ground on the wrong side which was causing a dead short.  If anyone else is doing this, get the multi meter and measure the contacts on the switch and you want the switching contacts to switch the two red wires on the dwg above.  The other is for the light.  On my switch, which I believe is the oem switch, the black goes on the top which is the "on" side.  The two reds are on the bottom.

That is great!  Thanks!  I appreciate all your help.

Hello ESP Support,

Your diagram is most informative and exactly what I want to do - change the stock e100 single speed control to variable speed control and remove the kick-start (minimum speed to activate) feature.


1) Will this work with Controller SPD-24120? I prefer this vs the 250W because the motor is only 100W and this 120W controller is smaller and thus more likely to fit in the enclosure area.

2) If it is OK to use SPD-24120, please recommend suitable Connectors to mate with that controller. Hard to tell from the controller picture.

3) The OP chose throttle THR-35. Is this a direct replacement for the e100 or a very easy swap?

Thank you.

This Razor E100 modification will work with the SPD-24120 controller however the SPD-24120 requires unique wire connectors that we do not have and have so far not been able to find. So the SPD-24120 is better suited as a direct replacement controller for a scooter that already has wire connectors which fit onto it.

However upgrading to a 250 Watt controller will increase the lifespan of the controller over using a 120 Watt controller because the controller is usually the weak link of the electrical system and the first part to burn out. A 250 Watt controller will not make the scooter go any faster than a 120 Watt controller would, it will provide slightly faster acceleration and will allow the scooter to climb steeper hills though.

The THR-35 throttle is a direct replacement for the original E100 throttle as far as fitting onto the handlebars, however it is a full length twist throttle instead of a half length twist throttle like the original. We have half length twist throttles available that are closer to the original throttle such as our item # THR-93 which is available on this page:

If you have any further questions about this modification please let me know.

Wow, thanks for the fantastically fast and detailed responses!

One last question, any chance you can list the dimensions for the SPD-24120 and SPD-24250? The space left in the internal box for the controller is tiny.

Thank you again very much!

You are welcome. SPD-24120 is 2-5/8" Long x 1-7/8" Wide x 3/4" High and SPD-24250 is 3" Long x 2-3/8" Wide x 1-1/2" High (not including its wires).

I just added the dimensions for the SPD-24120 and SPD-24250 controllers to their wiring directions pages. Here are the links to the pages:

SPD-24120 -

SPD-24250 -

I installed the new controller and everything seems to work pretty well with one exception.  The brake handle function is reversed.  That is, I can only get the throttle to work if the brake handle is activated. If the brake lever is not activated, the motor will not turn when the throttle is engaged.  I installed the plug according to the schematic above: yellow to red, black to black. How can I get the behavior switched to the way it supposed to be?

I have recently heard of some Razor E100 electric scooter brake levers having normally on switches instead of normally off switches. This must be the case with your E100 scooter. You could either disconnect the brake lever switch from the controller to disable it, or replace the original brake lever with a new brake lever that has a normally off switch.

I can confirm that mine has the normally on switch.  Using a tester, I can see voltage going to the controller until I engage the brake lever.  This is the opposite of what the controller needs.  Can you recommend an easily replaceable brake lever assembly?  

BTW: This was a really fun project and I highly recommend it.  The scooter runs beautifully (and I believe more safely) now.

The item # LEV-24 brake lever has a normally off switch plus a connector that fits the SPD-24250 controller. Here is a link to it:

I am finding a Razor E100 for my son. I searched and found some reviews of it. Should I buy it? 

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