Electric Go Kart With R/C Override

[Therealbradholley]

I've spent nearly every free moment over the last few weeks scouring the web for any information related to electric go karts and also radio control.

I've learned about servos, solenoids, actuators, voltage ratings, wattage ratings, ESCs, batteries, out-of-the-box r/c systems, arduino-based systems, live axles, dead axles, gearing, steering and safety.

I feel like I've got a pretty good grasp on the concept I'm going for, but there seem to be a few questions I've not yet found explicit answers for.

GOAL: To build an electric go kart for my son. To equip it with enough potential power that he can grow with it, and for me to be able to "govern" the power based on his experience and skill.

QUESTIONS:

1.) If I were to go with something in the ballpark of a 1500w motor, by what means could I adjust the power delivery so as to limit how fast he can go?

2.) When it comes to steering, I understand the difference between using a giant servo and a linear actuator, and i think i have an understanding of their respective strengths and weaknesses. But what I'm unsure about is whether or not i will be able to manually override either of them without damaging them. For instance, if my son wants to drive it himself, versus me remotely controlling it for him.

Has anyone built a go kart that was both manually operated and radio controlled? If so, would you have any advice for me? Anything you'd do differently?

I appreciate the time that any of you spend reading this and I thoroughly appreciate any helpful feedback.

Thanks guys!

 

[Quinc]

I've spent nearly every free moment over the last few weeks scouring the web for any information related to electric go karts and also radio control.

I've learned about servos, solenoids, actuators, voltage ratings, wattage ratings, ESCs, batteries, out-of-the-box r/c systems, arduino-based systems, live axles, dead axles, gearing, steering and safety.

I feel like I've got a pretty good grasp on the concept I'm going for, but there seem to be a few questions I've not yet found explicit answers for.

GOAL: To build an electric go kart for my son. To equip it with enough potential power that he can grow with it, and for me to be able to "govern" the power based on his experience and skill.

QUESTIONS:

1.) If I were to go with something in the ballpark of a 1500w motor, by what means could I adjust the power delivery so as to limit how fast he can go?

2.) When it comes to steering, I understand the difference between using a giant servo and a linear actuator, and i think i have an understanding of their respective strengths and weaknesses. But what I'm unsure about is whether or not i will be able to manually override either of them without damaging them. For instance, if my son wants to drive it himself, versus me remotely controlling it for him.

Has anyone built a go kart that was both manually operated and radio controlled? If so, would you have any advice for me? Anything you'd do differently?

I appreciate the time that any of you spend reading this and I thoroughly appreciate any helpful feedback.

Thanks guys!

I looked into this a while back. Way too much money and time.. Instead hook up a remote kill switch and call it a day. If you are still set on it check out the powerwheel boards.

 

[Functional Artist]

QUESTIONS:

1.) If I were to go with something in the ballpark of a 1500w motor, by what means could I adjust the power delivery so as to limit how fast he can go?
Thanks guys!

Many of the brushless motors have a (3) speed switch. (low, med & high speeds)

You could mount this switch on or in the rear speed controller area (out of reach of the operator) & adjust it as he grows & skill level improves.

Also keep in mind "gearing" with, lets say an 8:1 gear ratio & the speed controller in "low gear" the kart would probably only do like ~6 - 10 MPH.

* I like the idea of a "remote kill switch" it's a good "safety measure" for learning children.

 

[Therealbradholley]

I'm not opposed to the thought of simply using a remote kill switch. And if that were the case, let's say hes topped it out at 10, or even 20 mph and suddenly I cut it off. Would the cart proceed to coast at that speed (like a combustion engine in neutral), or do electric motors tend to have enough built in friction that they come to a quick
enough stop after power has been cut off? Ideally, he would know to hit the brakes before plowing into something, but it would be convenient if the car slowed down by itself as well.

 

[itsid]

if you'd get a controller with regenerative breaking, you can remote toggle the brake pedal signal
with the kill switch, which then puts battery charging loads on the motor
and it'd has a bit of 'resistance'.. it'd still coast though.

Another idea (probably not exactly a ideal one though) would be to toggle
the controller into low speed reverse, which effectively would act as a motor brake..
it's not very effective and it puts a ton of strain onto the motor, controller and about everything atached to it.
but it should still shorten the the stopping distance considerably.

steering: forget about it..
a rack and pinion setup and a servo-converted geared motor of significant size can make this work of course..
BUT it's a PITA at all times and you might throw enough money at it that you'd rather buy your kid a used car instead

But let me ask you something..
If your kid is too young to drive and steer.. why does he need a kart yet?
is it maybe a "dad wants a kart" situation and your kid is just an excuse?

Then make a kart for yourself and get a powertoy for your son until he grows into the kart.

'sid

 

[Quinc]

powerwheels are great cheap place to start for kids and modding fun for dad. Add an extra 6v-12v battery for more speed. Can upgrade gear boxes and motors etc. I started my kid at 18 months in a powerwheel and now at 5 he can ride everything from stand up jetskis to three wheelers.

 

[sikbrik]

Totally agree on all points leading you to powerwheels. Our kids all start driving them before they're allowed near karts. It sounds crazy but even driving games with a steering wheel have helped.

Then take them to a local rental kart place where safety is really built-in.

In fact, when my oldest finally got his own kart, I was confident enough in his abilities that I'd let him drive my car (I mean, I wouldn't...but you get it...he could if he was big enough.)

---------- Post added at 11:29 AM ---------- Previous post was at 11:24 AM ----------

Could a HD servo be mounted to a brake so that, if he activated the remote kill, it instead relays power to the brakes, eliminating the coasting issue?

 

[itsid]

good point on the servo actuated brake..
yes.. a hydraulic disc (the master cylinder for that matter) could indeed be nicely actuated by a big enough servo.

frankly, I wouldn't bother to find one really.. Instead I'd get a threaded rod and a nut
to build a makeshift linear actuator powered by a simple and cheap dc motor..

power on (with killswitch) and within a few turns the brake's fully engaged with a serious amount of force.

'sid

 

[Therealbradholley]

Haha! No, no. No hidden agenda here. The kart will truly be for my son. He's got a power wheel now, and he's certainly getting the hang of steering as it is. And I've done plenty of reading on "enhancing" those. Sounds to me like an upgraded DC motor and an H block would nearly triple the speed. And perhaps I'll still do that too, because he loves driving that around inside the house.

But my intention with the go kart is to have him experience and learn the feeling of driving an actual kart. Ya know; something more like a true race car, but built to his scale.

Having remote control of everything is probably excessive, but I guess I was looking at it from a safety standpoint. I wanted to be able to avoid injury to him and damage to the kart. But I suppose that may be more expense and trouble than it's worth.

Maybe I'll just stick to a kill switch with a servo operated hydraulic brake caliper. After all, I dont see any reason I couldn't hook up two calipers to the same disc. He can operate one, and the other would only engage along with the kill switch.