Young n00b wanting in the go kart action!

[Thesciman]

Hello all, this is my first post here on these forums, so I apologize for any mistakes. I am a young builder and I would love to build an electric go kart. My original idea was to use a cordless drill as a motor, bu after reading a few posts on here, some people said it's not a good idea. I was looking around for other motors and I thought I could use a big RC motor like this: https://www.hobbyking.com/hobbyking/store/__17707__XK5692_540KV_Brushless_Inrunner.html or this: https://www.hobbyking.com/hobbyking...r_1_5th_Sensorless_Brushless_Motor_760KV.html
I would also get a 200 amp speed controller and could run it of two car batteries in series. It would most likely be a birthday present but I would like to keep the price below $600 for the electronics. As for tools I have:
An angle grinder
A hack saw
And a MIG welder

To wrap it up, will a big brush less motor have sufficient torque? And if not, what does?

Thanks very much
-Thesciman

 

[Poboy kartman]

Welcome to the forum. Glad to have you. Now for all the stuff you're doing wrong. ..there is a section for electric karts. ...no biggie- but better posted there.
A bigger peave of mine- fill out your profile- at least let us know where you are from. We have people from all over the world here.....

 

[Thesciman]

Alright, thanks. I've filled out my profile and I'll move it to the appropriate forum. Who is the admin here?

 

[dcastillo]

your links didnt work for me.....
Ive got a treadmill motor on mine right now, pushes the cart and 275lbs of people at 12mph no problem (motor is around 800W)

 

[Thesciman]

Sorry about the links, I'll fix them when I get home. The motors were 4800 watt and 18000rpm @24 volts. Is the treadmill motor AC or DC? What voltage are you running?

 

[itsid]

links from his other thread

https://www.hobbyking.com/hobbyking/store/__17707__XK5692_540KV_Brushless_Inrunner.html
https://www.hobbyking.com/hobbyking...r_1_5th_Sensorless_Brushless_Motor_760KV.html

Well, I wouldn't say that RC motors will stand the load on a go kart.
And, although I've never tried, I doubt they can provide the torque without one heck of a gear ratio, since they're made for revs not to move heavy objects

'sid

 

[Thesciman]

I read through the stickied thread again and I saw a few other options. Would this 500 watt, 24 volt motor work?
http://tncscooters.com/index.php?route=product/product&path=52_55&product_id=59
And maybe a 30 or 40 amp controller like this?
http://tncscooters.com/index.php?route=product/product&path=41_73&product_id=495
Again, two car batteries in series plus 40 Kg rider

 

[Thesciman]

Let's start with the basics

Hi again, the other thread of mine was not letting me post.
How much would an electric go kart cost? I would want at least 20km/h with a 40kg rider. Would this 1000 watt motor and controller work?
http://www.monsterscooterparts.com/48v-1000w-motor-controller-throttle-kit.html
And how much would I need for the frame? And I would like around 1-2 hours of runtime. Thank you all!

 

[ML-TOYS]

I would say anywhere between $1.00 and $1000.00

You can build a basic kart or go all out with suspension and a cage. You need to say what you want to build. How big you are, weight capacity. Dirt or street use etc etc etc

 

[dcastillo]

agreed, way to many variables, as Ive learned in the past 2 months with mine...
the batteries needed for that motor and your desired runtime will probably cost you the most....
I run about 900W on mine at 12mph and can squeeze out 25min of runtime from 9ah batteries, buts that mostly on the road, not offroad which would be much less...

-Danny

 

[Thesciman]

Sorry for the lack of info, no cage and maybe a suspended rear axle. I am 160 cm and 40kg. Mainly street use, but it may see some dirt.

 

[Thesciman]

I was thinking about it, and I thought that I would need to buy 4 batteries online and shipping must cost a fortune. Could I get away with a cheap 24 v starter motor from ebay? And I could use my 2 12v deep cycle RV batteries?

 

[itsid]

Well, the 1000W my1020 will work, although I would try and find a set with a throttle-pedal, not grip.

Other than that it's pretty much want you want for a convenient start building an e-kart.

You can get cheap batteries almost everywhere (larger motorcycle batteries for example, or smaller car batteries will do for a while)

Yes, with some modification a truck starter motor will do nicely,
BUT be aware, since they come in various poweroutputs (1.6kW up to 10kW)
you may want to be on the lower end, since a 10kW motor wants to draw 420Amps ,
you need one beefy controller to achieve that and if you find one, that thing will be expensive ($500++)
So, before you buy a startermotor check it's powerdrain (wattage) and see if you can find a controller for that first.

'sid

 

[Thesciman]

Thank you sid, that's some great help. Appreciate the advice. With the starter motor, how long could I run it for before it needs to cool down? Let's say on a perfectly flat and straight sidewalk. And how would these SLA's perform?
http://www.ecomelectronics.com/prodinfo.phtml?id=3300031&ref=shopbot
Again, thanks. This is a great help.

 

[itsid]

how long.. depends those starter motors are pretty solid, so they can stand a lot of heat without any issues, I'd say as long as your motor doesn't hit the 80°C mark you should be good (that is if you don't touch it, otherwise yor fingers will be toast).
To be on the safe side I'd say run them at 60°C max to have them last almost forever,
except for the brushes that need to be changed every once in a while

dcastillo posted some thermometer stickers a while ago, I think you might find those useful too
(I see if I can find the link later)

For the batteries, that depends on the wattage of your motor of course.

Basically you can estimate the endurance of a batpack like this:

batteries in series only add up voltage, NOT capacity, so 2 12v 18AH batteries in series are one 24V 18Ah batpack.
2series 2 parallel (ie 4 batteries) on the other hand make one 24V 36Ah batpack... you get the idea.

The motor draws a certain amount say 2000Watts (or Volt Ampere) meaning at 24V it draws ~84Amps (24Volts x 83.333Amps = 2000Watts) at full power;
a bit more, but since the motor will not be at full power all the time you should be okay with 84.
Now the 4 batteries batpack provides 36Amphours at full power that is 0.43 hours of fun or about 25 minutes.

Now thats the theoretical value, it very much depends on the actual power draw, which depends on weight, road angle, motor temperature and things like that, so assume 20mins of fun with a four batterie pack of 12V 18Ah and a 24V 2kW motor.

'sid

 

[Thesciman]

How about this setup:
My1020 1000watt 48 volt motor
http://www.monsterscooterparts.com/...t-11-tooth-8mm-05t-chain-sprocket-my1020.html
Generic 48 volt 25 amp controller
http://www.monsterscooterparts.com/48vo12unscco.html
This random pedal
http://tncscooters.com/index.php?route=product/product&path=65_79_83&product_id=88
A 40 amp fuse
http://tncscooters.com/index.php?route=product/product&path=46&product_id=209
4 pack of 12 volt 18Ah batteries
http://www.ecomelectronics.com/prodinfo.phtml?id=3300033
My estimated runtime was ~40 mins.
That My1020 had an 11 tooth 8mm chain. Which size sprocket if I'm using ~10 inch wheels and tires.
Thanks so much, you guys are a great help.

 

[itsid]

look around I've seen the 48V 1000W my1020 for under $100.
example:
http://www.motiondynamics.com.au/unite-my1020-1000w-3000-rpm-48v-dc-motor.html

I'm not sure what the peak amperage of the my1020 is atm..
and if they say 25Amps max, that could also mean 25A for max 10sec then 8Amps *shrugs*
So I'd suggest this one:
http://kellycontroller.com/kds48050e50a24v-48v-p-282.html
double the amount of peak Amps at basically the same price.

the pedal looks flimsy being all plastic so;
and since I don't know what type it is (poti hall voltage etc) I don't know if it fits the controller I just mentioned,
so here's a pedal (5v hall effect - metal) that matches the kelly controller
http://kellycontroller.com/simplified-5v-throttle-pedal-p-1028.html

The 40Amp fuse should be great here, it's more than enough to handle all possible draws, it blows sooner than the controller reaching it's peak...

keep in mind, that at 48V your four batteries batpack only provides 18Ah!
for a 1000W (~21Amps) motor that's roughly 40-45 minutes of driving (theoretically up to 51).
If that's enough, then you're good to go

For the gear ratio, that thing is rated at 3000 rpm so I think an axle sprocket should have 48Teeth at least (55 maybe) giving you a ratio of 1:4.4 to 1:5, that should get a lighter kart with small (10") wheels going with no problems.
that'd be something about 18-20mph btw

'sid

 

[Thesciman]

Thank you soooo much sid, that's the best post ever! That is the ideal kart for me! Would steel be ok to build it out of? Again, thanks I really appreciate it.

 

[itsid]

Steel is perfect.

1" round or square tube, thin wall (1.6mm, 1/16", 0.0625", 16 ga) will be fine

And if he says so, I'd bet my left foot on that

Just make sure you have really good welds, and know enough about the kart geometry
(Ackermann steering, optimal trackwidth - wheelbase ratio etc.)
to make a frame yourself, otherwise it might be a wise decision to just go and buy a commercial rear engine kart frame off of ebay or CL or something.
You can always make your own frame afterwards when you have all the experience and info you need to do so

'sid

 

[Thesciman]

Could I use a frame like this instead of making my own?
http://www.bmikarts.com/Azusa-Go-Kart-Kit-with-5-Nylon-Wheels-AZ3557_p_1865.html