is this the speed restriction chip in the new emax

aidanworthington's picture
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untitled.JPGiv found a hand soldered chip in my new emax in a out of place place does any one know what it does. the chip says on it 725158 sfh6 156-3 x017 allso there is a small ceramic cap 104 attached.
look at the pic it is at the side of the 6 larg caps look for the small orange ceramic cap

before comments


aidanworthington's picture

iv found out what the part is . it is a oplocoupler it is used to comunicate between two seperate circuts without interferance ie diferent voltages or impeedances. its apps are swichmode power supply'telecom'and battery powerd equipment basicaly its a way of monertering the frequency or power of a circuit so the question is still the same is it a restrictor.i know the speed controler is softwere based for max amp and diffrent mode settings but there is a fuecuency setting on the softweare but its a cut of point . no signal = no cut of point. any ideas of what i should do next or should i just un solder it on the transister side and c what happens.


if you block the signal to the controller logic side, the controller won't run the motor at all.

The controllers processor recieves the signal as 3 x on/off signals, 1 for each phase.
It uses these signals to know when to power each phase and in which direction.
it also uses these signals to calculate motor frequency and rpm.
The two functions are separate able only in software.

The only way to trick the controller into allowing a higher top speed i have seen work is to change the clock crystal.

btw, when you start the bike, what software revision does it display?

if you are lucky, and it is the same one my programming device is designed for, i could lend it to you to change the max speed setting.


Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah in July 2010. Done 194'000km

What max speed are you getting now Matt? And how's the range when you've modded it.

I've a 110s. Not sure of which revision. Will check.

aidanworthington's picture

thanks for the reply. when i turn it on it says V1.11. Bowowing that reprograming box of tricks would help alot if its the right version for my scooter. If u did il send u a check to cover all postal costs and so on. Thanks for your help (aidanworthington [at]


Hi guys,

I can't remember which revision my programming box was made for, i will have to double check. This might take a while, as i no longer run the original motor and controller.

when running the original controller, programmed with no speed limit, it would top out around 47kmh at 48v.
when i bumped the voltage up to 60v, top speed increased to 55kmh.
i brought it back to 48v, however, the hall sensors developed a problem, and now that motor/controller combination no longer works (controller reports hall sensor failure).

Emax actually have a second line of scooters that will do 60kmh, intended for the US and Australian markets.
These have a slightly different controller, and motor (fewer windings of thicker wire).
My (strictly speaking the distributors) 90s now has these.

As far as range goes, i never did measure it.
however, back when it was completely stock, it did run out of juice at 40km, however, i didn't have any instrumentation on it at the time.

With the new motor and controller, i will be using a TS 48v (16 cells) 90Ah pack.
I will use a cycle analyst to measure actual energy usage, and will report back when that is done.
Although it wont be quite the same setup, it will give you an idea of how much energy going 60kmh requires.


Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah in July 2010. Done 194'000km

aidanworthington's picture

sounds like good honist fun to me. I was thinking of a simular idea myselth but my involved adding a dc to dc converter and wiring all the lights and stuff to work separetly and a new frount wheel with a good old speedo so i can plug and play with speed controlers with out worry the only thing the original motor up to the job iv read it can easly handle over 7kw and i think it will cos at the moment doing 30mph on a steady incline only makes it 5 dec warmer at a guess. but i gave it a proper test the other day by going up a 1 in 4 (500 meters worth) and it was'nt happy but it did it(16 mph:{ ).It didnt get to hot thow only 25 deg at a guess.I think that it was a lack of ampage what caused the slow speed but hopefully that will be sorted soon.the controler i was thinking of using is a programable kelly 200amp 48v .

But at the moment il only wire the lights up to the dc to dc converter till i save the penies for the messing with the original one is the only option at the moment.

obviously you know your stuff what do you think


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