Electric Tony Kart


10 mW
Oct 29, 2021
So I decided to start a little build thread for my Winter project but first a little info about myself.

I grew up in Denver Colorado and moved to Europe in 2004. I currently live in the land of the Oktoberfest :mrgreen:

I have been racing Motorsports basically all my life but have little to no experience with EV's (except for my private daily driver)
I am learning a lot while building and will definitely have more questions than answer's :D

My plan is to build a pure racing kart that has absolutely no BLING BLING and that won't look like a spaceship Elon has developed. I want it to be light and what ever it doesn't REALLY need, it won't have. The motor I will be using is a QS 138 90h paired with a Fardriver 96850 controller. Originally I wanted to use a Motoenergy ME1507 motor with a Sevcon or ASI controller but after reading that the ME motor underperforms and can have heat issues I decided to go the cheaper and more, Chinese route. I want to be able to program the controller myself just because I want to learn about the process and clearly because paying for a 30min password in order to change something will not work in the pits at the race track. So I decided to get the Fardriver. We will see how it performs.

I am using a Tony Kart 401 shifter Chassis I got relatively well priced. It has a 50mm axle and front brakes what was very important to me. I had to get a new rear axle in order to run the motor on the outside, rebuilt the brakes and lines and did a big service on the chassis. Everything is straight and nothing is cracked.

I really wanted to build a battery pack myself but might put that on hold until I build a Bambino kart next year. I have a lot of respect with electrics and don't really want to put my garage on fire that I just built :flame: :lol: so I am looking to have a pack or maybe two built. I might have a deal in line for a 84V pack made from eig cells for a decent price, it is a little bit heavier but no solder or weld joints, and it is fairly small.

Here are a few pictures from the beginning:


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Got the new rear axle and sprocket installed, I will be starting with a 15-30 gearing which will give me around 100kph without FW, already thinking this could be too long.

I also installed an adjustable steering wheel mount, definitely a must for someone with short arms like me :eek:


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thanks, i am trying to keep everything clean and well organized. I will try to cover everything up nicely to give it a more 'tidy' look.

I have read that thread, not just one time :eek: Nuxland has a completely different approach to his build than I am going for. I will be trying to keep the Kart as light as possible. No forced air cooling, no water or oil cooling, no contactors or Lipo bricks. I am hoping to keep up with the Rotax Max class, so the 125cc two strokes without a gearbox.

My Motor mount, Motor and Controller have finally arrived. I will be mounting everything to see how it fits. I still need to make a Controller mount and a "cover" for the controller to keep various debris etc off of the controller.
I see several pieces of bodywork it doesn't REALLY need.
Chalo said:
I see several pieces of bodywork it doesn't REALLY need.

well I guess you are right BUT the FIA CIK rules say what bodywork you need and can have, I might be trying a different front section that should be slightly more aerodynamic. I guess the weight you would save removing the bodywork, would be obsolete because of the terrible CV rating a kart without bodywork would have.

I might try to fit a Tony Kart M7 nassau panel, it apparently has a significantly better CV than my current nassau panel.


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Chalo said:
I see several pieces of bodywork it doesn't REALLY need.
The kart doesnt “need” the bodywork, ....but the driver does !
Their primary function is collision protection for the driver by reducing impact forces and preventing wheels interlocking in close racing. There should be one on the rear also when racing .
Their weight is minimal..compared to the “x” kg of battery that will be required to keep up with those 125 two strokes !
Finally found some time to paint the Motor mount and fit the Motor in. I also installed the throttle and cables 👍🏻

I am currently working on the controller mount and a cover for it. Has anyone experience in cutting carbon fiber? I would like to make a top cover for the controller, probably 2mm carbon fiber and I am not sure if a dremel would work adequately. I also need to make a fitting for the steering wheel where I will install a small battery monitor, regen button and the on/off switch.


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Hey Wimbi! Fellow (ex) kart racer here. Looks like a fun project!

I just checked and the Rotax Max are spec'ed at nearly 30hp (22kW). When I try to look for the QS138 90H specs I only see numbers like 4kW and 7.5kW, maybe 12kW peak. You'll keep up out of the tighter corners, but the Rotax will eat you up on a long enough straight. Depending on track configuration you could still win.

Maybe I'm not finding the right specs for your motor?

I think you can cut carbon fiber the same way you cut fiberglass (with a saw). Just be sure not to breathe the dust (as in, use a respirator).
Yeah you're right, the QS motors are very underrated. The 138 90h motor should pull peaks up to 30kw without overheating, I have seen some pull even close to 40kw, I do not intend to push the motor that far though. My target would be to keep up with the 125 TAG karts. On our tight track I think that should be doable ( KZ top speed 125kph, TAG top speed 110kph). I definitely dont want to need forced air, water or oil cooling. I think keeping the weight as low as possible will prevent a lot of other problems.

Other builds have far more strong motors (Zero 75-5 etc) and run at the absolute limit, they get hot so a lot of active cooling is needed. If a kart has close to 60w peaks, weighs over 40kg more than I dont think that will make it much faster laptime wise.
I see. Looking at the 125 TAG karts, I see no gearbox, so yeah, if you can get close on power/weight, you should be able to easily beat them with your 'way more area under the power curve'. But getting close on weight means some amount of compromise on runtime. Getting enough battery capacity without weighing the kart down too much feels like one of your larger challenges.
I agree, the battery capacity is definitely a compromise. The cells I will be using are slightly heavier (eig cells) but 26kg for 3,2kwh is ok. I am hoping to get around 15min of tracktime (fairly tight track, longest straight is only around 250m)
There are multiple TAG 125 classes with various weight, and age requirements, etc .. ranging from 155kg,..to 200+ kg (kart and driver) ,..so depending on what class you pick, (and how much you weigh ?) you could be competitive.
However, as you probably know, regs are a minefield ( EG.. are front brakes allowed in your chosen class ?), especially for “official” race events, but even for just practice days, some tracks can be “A’holes “. over minor details like tyre choice, electrical safety, etc etc.... so its best to know a friendly club to run with
So I had some spare time and finally got some work done. I got my battery built and wired up the BMS, I had some issues with the app at first but was able to sort things out. Now I just need to start on the battery mount and some sort of stainless case. Does anyone know of someone who can build a case in Europe?


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I also fabricated a small instrument panel for the steering wheel. It is 1,5mm carbon fiber and was pretty easy to cut and sand. I think I might build another one that looks a little "cleaner".

On the right side is a momentary button for the regenerative braking, a on/off switch for the controller and a 3 speed switch. On the left side is a momentary push button for reverse.

On the bottom is a simple shunt type battery monitor.


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I also started to do the wiring for the controller and actually got my first "beep" from the controller. I am not sure if I will route the battery wires through the front, or maybe behind the seat. I wanted to keep them as far away from the phase wires as possible.

I still need to fabricate a mount and cover for the controller, I will be doing this next.


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Have you weighted your stuff?
1. motor with mount
2. controller with mount
3. battery + batterymount
If you are building a very light build then you should use aluminium and not steel for mounts :)
You are absolutely right Nuxland, and originally I did want to have a motor mount custom made of CNC aluminum, I put that on hold because of the crazy amount the person wanted that could have built it. I got my mount from MightE in the UK, he makes them in bulk for the 90h motor. It was an easy and cheaper way to start. I am gaining about 800 grams with that mount, everything else is aluminum or carbon fiber. I would like to have a mount machined out if magnesium, I will finish the kart first though :lol:

I want to protect the battery, so I need some sort of casing. I don't want to just shrink wrap it and hope nothing happings. I still don't know if SS or aluminum would be more adequate. Maybe a frame with aluminum angles and walls out of carbon fiber? I would like to fit the E stop button and on/off switch for the BMS in the battery case.
"My plan is to build a pure racing kart that has absolutely no BLING BLING and that won't look like a spaceship Elon has developed."

LOL. Subscribed.
Sweet build so far, exactly the kind of thing I'd like to do someday :bigthumb:

If you have troubles to find someone to build you a battery box, maybe you can try to search for some kind of toolbox. Either plastic or metal ones exist, they are relatively cheap and some of them can be waterproof. You just need to make sure you can fit the battery in it.
Amazing Project !

I've got the exact same motor and the exact same mount from mightE ! I am building an off road go kart !!

I'm planning on using an ASI BAC2000 controller as I have programming experience, but looking forward to your build.

Please do share 0-60 times !
Thanks guys,

things have been coming along. I fabricated a mount for the controller and Battery out of Carbon fiber to keep the weight down. I also ditched the original plan of wiring the discharge wires through the front and on top of the floor tray. I will be routing them behing the seat, seems to be neater and less cluttered.

I was thinking about making a case for my battery, I searched almost every page on the internet and couldn't find anything that would fit the c020 cells so I decided to make one out of 10mm ABS sheets. It seemed like a good and clean idea until the sheets arrived. The box would have been way to bulky and looked out of place on the Kart. I got myself some 2mm Aluminum sheets and will be making something next week. Most probably not a box but a ''cover mount'' thing that is fastened with four bolts to the Carbon fiber battery mounting plate.

If i decide to build a second battery, I am guessing I would want it with 21700 cells, just because of the overall volume these pouch cells take up. I just didnt want to spotweld or solder my own pack. Maybe I can find someone in my region that can spotweld safely.

I also finally got the Motor running and was able to dial it in (well as far as I could without load) My brake regen button seems to be working great with little to no delay, also 3 speed and my momentary switch for reverse work great.

I will be uploading some pics of the current progress tonight! I am hoping to test drive it within the next week if all goes good.
Here are some new pictures of the current progress. You can see how bulky the battery casing is, I cut everything so it would be a tight fit on the inside, but I just felt as if it didn't look right or wasn't in place.

I made the battery mount out of a 5mm carbon fiber sheet, it was fairly easy to cut and drill, I just need to countersunk the holes so it will have a nice flat surface.


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