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Petrol kart conversion to electric

Hi , long story short i bought my eight year old son a petrol kart to try get him into the sport, problem is he hates the noise, so i am thinking of scraping the motor and converting to electric, now its currently a 60cc 2 stroke and should reach 40 mph or so, possibly more (never used it) , question is what sort of watt moter and battery should i use to get decent results? I do work with batteries as a job so should be able to build whatever size battery pack, there are 1000w moter kits on ebay but would this be enough to do the job, thanks in advance, here is a pick of the kart as it sits20210221_111451.jpg
 
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A 60cc two stroke engine is possibly in the vicinity of 8hp given the power pipe in the photo.

8 hp is approximately 746 x 8 is approx = 6Kw.
So six of your choice motors and batteries to suit.
This in itself adds extra requirements for power, bit like the space shuttle.
Impracticle I would think.
 
What about a small car starter motor. They will produce several Kw of power. Suitably geared down of course.
 

Harald Kapp

Moderator
Moderator
I can also use the gearing to gain power and ecceleration
gain power? No. Where would that additional power come from. Any gear will reduce the power available at the wheels. Gearing is used to have the motor work in its optimum range of power generation and adapt the motor speed to the wheel rpm.
An electric motor has a wide range of operating speeds and creates torque at very low pm. Therefore electric drives are usually not geared or use only a low number of gears.
What about a small car starter motor. They will produce several Kw of power.
Would a starter motor work for 30 minutes or so? I think, but I'm by no means an expert here, starter motors are designed for short term operation only and will overheat easily when operated constantly for a longer time.

At ~ 6kW you will need a 3 kWh battery for 30 minutes operation. Plus some spare kWh as you don't want to drain the battery completely and you'll also want to account for ageing. At 12 V that amounts to 250+ Ah. Quite some battery.
Have you given thought to an electric bicycle conversion kit? You get the motor, the controller and a suitable sprocket to drive a chain. These kits come with or without battery, so you can use your own custom battery. The thing you'll have to watch out for is that you get a kit with manual speed control. What are the regulations in GB? In Germany electric bikes are required to support only while the rider is pedaling. You don't want that kind of controller. You'll want one where speed can be adjusted manually. On a bike that would be a grip on the handlebar. You'll have to adapt that to a foot operated pedal, I think.
 
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