Electric Kart - First Build need your guidance please

[Driftking]

Hello everybody!

I want to make my first electric vehicle - a drift go kart.

I will use a typical kart frame (modified) and use some PVC piping on the tyres to aid in drifting. I would like your help selecting the right components to avoid unnecessary pain.

From my understanding the main things are the motor, controler and battery so lets start there.

Option 1 - Kunray 1020 but I have heard some nightmare stories about it with the fardriver controller. Also 3Kw might be a bit on the short side.

Option 2 - Kunray KR5V + fardriver controller - seems like a good option maybe up to 8Kw is possible?

Option 3 - You tell me

Battery I'm thinking 72V 20AH. Should get me some nice running time

Sorry for the noob questions and thanks for any help!
Drift King

 

[amberwolf]

Some thoughts:
How much power do you need to go the speed you want to go under the riding condtions you have?
How much torque do you need to accelerate at the rate you want?
(and if necessary to break loose the traction on the wheels to drift?)
How much power does it take to get that torque with the drivetrain you want to use?
How many Wh does it take to get the range you want? Meaning, how many Wh will it take per mile to run the kart the way you want to, under your riding conditions?
How much weight can you add to the kart? Meaning, how much does the gas engine and drivetrain weigh, vs the electric one, vs the weight limits of the kart itself in regards to performance?


If you haven't already, you may want to look around at the other kart builds (some in this subforum, some in Large EV General Discussion ).

 

[Driftking]

Most of those answers are very hard or impossible without previous experience.

Equivalent Gas powered karts are around 6/7KW so I think this is a good target.

The KR5V motor by Kunray should supply this along with a suitable 100A controller...

Can I get this sort of power from a 24AH 72V battery or am I pushing too much C Rate?

 

[Chalo]

Equivalent Gas powered karts are around 6/7KW so I think this is a good target.

EVs because of their more immediate power delivery and wide power band, typically need less peak output to do the same job. Paradoxically, if top speed is a key factor then they may need more peak power than an ICE vehicle, because of naturally diminishing output as they approach maximum motor RPM.

Electric motors are rated for the continuous power they can produce, which is contrary to the way liquid fueled engines are rated. Usually electric motors can produce a multiple of their rated power for short bursts, or with active cooling. That's contingent on the battery and speed controller being about able to deliver enough electrical power.

This is to say, you probably can use a 3kW rated motor and expect to support power peaks of 2-3 times as much, within the limits of your other components and the thermal management of the motor.

 

[Driftking]

Thanks... I understand but I prefer to have some spare power. Man Math I guess

So far the specification I am looking at is:

Battery: 72V 24AH
Controller: ND 72360
Motor: Kunray KR5V

Max System Amps: 100A

Will this work? I'm worried the battery will be under too much strain at 100A but I guess the motor will not be pulling that much all the time.

Thanks!

 

[E-HP]

Will this work? I'm worried the battery will be under too much strain at 100A but I guess the motor will not be pulling that much all the time.

Depends on the cells you choose for making the pack. The Molicel P50B 21700 can output 60A, so a 5P pack (25Ah) could do 300A. A Samsung 50S will do 25A, so 125A for the pack, but still some headroom over 100A.

 

[Driftking]

Thanks E-HP, do you think that I need a BMS with bluetooth communication or not?

I can always 'tune' the battery on the motor controller... as long as the BMS supplies enough juice.

Another part I need is a TPS (throttle position sensor) for a metal throttle cable - basically a 'throttle cam' TPS.
I imagine something like this:


Where can I find such an object?

 

[Chalo]

Thanks... I understand but I prefer to have some spare power. Man Math I guess

So far the specification I am looking at is:

Battery: 72V 24AH
Controller: ND 72360
Motor: Kunray KR5V

Max System Amps: 100A

Note that after efficiency losses, nominally 7.2kW electrical power will be less than 6kW power to the wheel, and that much only near peak efficiency. The breadth of the electric powerband might make it competitive with more powerful gas motor karts, but you can't have 7kW out if you only put 7kW in.

 

[E-HP]

Note that after efficiency losses, nominally 7.2kW electrical power will be less than 6kW power to the wheel, and that much only near peak efficiency. The breadth of the electric powerband might make it competitive with more powerful gas motor karts, but you can't have 7kW out if you only put 7kW in.

I watched a few videos of kart drifting and ekart drifting. Because of the peak torque being at the lowest speeds, the electric motor seemed to be able to break traction and drift pretty easily. Seems like higher speeds aren’t really achieved in this type of racing, like with regular karting.

 

[Ciclon]

I was going to post a new thread and the new thread bot said my intended post was already being discussed so I will join here with both my thoughts and questions.

FIrst as to the OP.

IMO that Kunray bottom of the barrel stuff isnt going to get you anywhere near a true drifting kart. Simply not enough power and it is almost guaranteed to overheat. Drifting is not a gradual and sentimental stepping on the gas pedal. Its balls in pedal to the metal almost all the time. Going above the rated power output of an electric motor will just not work for anything longer than a few minutes. Spend a bit more money and use a QS135 28KW based kit such as the one from electro and company or a Siacom SIA 155-64 Hairpin motor kit and then throttel the output down to keep temps in check. As a disclaimer, this is just my uneducated guess as I am personally not an e-kart drifter but I do have years under my belt of road racing experience with decomposed bone based fuel burning engines.

EMX® QS138 90H Kit

The "4kW" 90H model of the qs138 family is the most powerful of the bunch. Sporting a longer overall length means a longer rotor which in turn means more torque. This motor is well suited for larger power sports applications or high duty cycle situations like Karting that require that extra...

electroandcompany.com

https://www.aliexpress.us/item/3256806567519386.html?pdp_npi=4%40dis%21USD%21US%20%241%2C236.60%21US%20%241%2C162.40%21%21%211236.60%211162.40%21%402103244417374294914313065e86f1%2112000038193819545%21sh%21US%212708511766%21X&spm=a2g0o.store_pc_allItems_or_groupList.new_all_items_2007550890687.1005006753834138&gatewayAdapt=glo2usa

There is/was an older dude here from Estonia that IRRC has gotten his motor to run over to over 50KW. The thread below can teach you a lot about e-karts.

Electric kart

Took a Tony kart without motor and installed batterys and electric motor. Motor: GM 10kw 48V and 100kv I think. Battery: 16x 60Ah Winston Controller: GM VEC500 48V Motor speed with wheels of ground was 4700rpm. Rear wheel size is 11" :) and theoretically top speed should be 81km/h. First day...

endless-sphere.com

Now to my own questions.

Are there any complete kits (motor + controller + throtte etc) besides the two I mentioned above that are at, or over, 30KW suitable for a shifter kart retrofit? I have a Tony shifter kart with a Fireball engine (28.5 HP / 15,580 RPM) that decided to go BOOM while doing donuts and instead of replacing the engine which runs at about $2500+ I am looking to go electric. You know. To safe the trees and shit.

Carnage here: