Help With New Kart Build

[JokerBen321]

Help With New Electric Go Kart Build

Hey everybody, I am new to this whole thing but need help with my new go kart build... I am looking at buying a used frame off of eBay or building a simple wooden one this summer. I need help with my motor choice for this kart... I have toyed around with the idea of getting a golf kart motor but at 400-500 dollars, it is way out of my price range... I am hoping to keep this entire project under 500. I have looked on eBay at the 800w 36v motors and I want to run 2 of them but don't know how to wire them or install them on the live axel(I would overvolt them to 48v). I have also looked at the Turnigy SK3 brushless motors from hobbyking, but don't know what controller I would use... Is there another motor that someone recommends around $100? I want the highest possible wattage... And if there is, what controller would I need to then overvolt that motor to get extra juice out of it?
Thanks,
Ben

 

[chancer]

Don't build a wooden Go kart.
Also check your local Craigslist for used frames and Karts Rather than ebay.
Welcome and good luck.

Sorry I do not know about electric motors and such.

 

[JokerBen321]

Thank you for the quick reply... Ill go check out craigslist. And sorry everybody I didnt realize there was an "Electric" categorey when I posted this...

---------- Post added at 11:56 PM ---------- Previous post was at 11:50 PM ----------

What about the Razor ground force? ...throw some bigger tires on that with a new power system... I should be able to fit in it (I am quite small). Someone on craigslist is selling one for 175$ which is pretty steep but oh well...

---------- Post added 04-17-2016 at 12:32 AM ---------- Previous post was 04-16-2016 at 11:56 PM ----------

If anyone on here knows of any cheap, lightweight go kart frames please let me know!!!
Ben

 

[JokerBen321]

Hey guys so I originally posted a thread on the "All Things Go Karts" section because I was stupid... And I didn't really get an answer over there so I am literally going to copy and paste what I typed up in here:

"Hey everybody, I am new to this whole thing but need help with my new go kart build... I am looking at buying a used frame off of eBay or building a simple wooden one this summer. I need help with my motor choice for this kart... I have toyed around with the idea of getting a golf kart motor but at 400-500 dollars, it is way out of my price range... I am hoping to keep this entire project under 500. I have looked on eBay at the 800w 36v motors and I want to run 2 of them but don't know how to wire them or install them on the live axel(I would overvolt them to 48v). I have also looked at the Turnigy SK3 brushless motors from hobbyking, but don't know what controller I would use... Is there another motor that someone recommends around $100? I want the highest possible wattage... And if there is, what controller would I need to then overvolt that motor to get extra juice out of it?
Thanks,
Ben"

Someone told me to not build a wooden kart and to look on Craigslist. I did and found a couple 100-150$ karts that I could pick up. So basically I just need to know:
-what motor system everybody reccomends (~200 total for motor and esc)
-what batteries to buy (most likely some 12Ah SLA packs)

I want to hit around 25-30mph and have pretty solid acceleration.

Thanks,
Ben

 

[landuse]

Unfortunately your expectations are a little above what is possible in the price range you are looking. With $200 for engine and all that goes with it, you are just not going to make it. There are not too many electric guys n this forum

Sid is quite knowledgeable with electric....hopefully he replies soon

 

[itsid]

I'm here Paul

First Ben, please read this
500 is a tight budget and you'll barely be able to build an electric kart with that;
the motor itself isn't the problem either,
sometimes (if you're lucky enough) you can find a nice big one for just a few bucks..
but that controller you'll need to power it rips a giant hole in your pocket, and even if you're lucky enough to find that as well..
just think about how many batteries you'll have to carry around (and what they will cost)

A set of batteries alone can easily set you back a few hundred dollars alone.
(especially for high power motors)

Aanyways, read the thread I linked above, it tells you how to estimate the motorpower you'll need, and it gives you a hint, why RC motors are just not what you want.

With that, come back here and we'll talk about that in more detail

"around 100 dollar motor suggestion":
Find a unite motor my1020 with 1000W (either 36 or 48Volts)
100-130 is a good pricerange for that.. take care, some idiots sell them for 300 or more.
and yes that will easily outperform a turnigy from hobbyking with triple that powerrating

'sid

 

[JokerBen321]

Thanks for your replies. Okay so I read that thread... So I don't over volt the motor... So you think that a 36v 1000w motor is my best option? What ratio for the gearing would I want then to get fun acceleration and solid top speed? And what is the difference between getting a 36v motor and giving it 36v, and getting a 48v motor and giving it 48v? With the currently selected motor, what would the performance be like? I read that forum's math but it was pretty complicated... (I weigh 100lbs but idk what the cart weight would be).

So I found one of those motors for about 100, and a controller for 40ish. If it is worth it, I can stretch my budget and get two of those motors/controllers, but how much would that help? Is it worth buying extra batteries? Or is there a way to wire both of them from the same packs (and just get higher Ah rated batteries)?

 

[itsid]

I can't tell the total weight of the kart either, nor can I tell what you want to do with it.
it's on you to find out.

estimate the length of steel tube you need to make it, find out what it'll weigh per foot..
the weight of a battery can be pulled off the internet as well..
but you'll have to do some research.

And that's already needed to estimate the gear ratio in the end.
and what you think of at "solid top speed" is what I think of as "length of rope"
So you need to be more precise.
Or again, do the math...

A second motor and controller will pop open a whole new can of worms to be honest;
since you have to amke sure they're perfectly synced and that's much more difficult than you might imagine.
if you play with that idea make sure to buy two motors from the exact same batch (consecutive serial numbers if possible) and the same for the controller;
that way you have at least the best possible starting point to tackle that problem
but yes, it'll double your motor power and half your mileage.
(or double the weight of the batteries... of course)

'sid

 

[NotSoMasterMind]

Let me just say, never build a wooden kart. They are heavy and fragile (not to mention they are hard to use with materials and stuff he have today) and they just look god**** awfull. I would suggest getting a washing machine motor, sounds funny right now but they work. Also try to get on craigslist and find a frame. I found one for $100 and only thing i need to do to it is paint it, and just weld things on to it. *note: not to mention it is harder to attach modern things to a wooden go kart than a metal without the help with a welder

---------- Post added at 06:32 PM ---------- Previous post was at 06:27 PM ----------

Thank you for the quick reply... Ill go check out craigslist. And sorry everybody I didnt realize there was an "Electric" categorey when I posted this...

---------- Post added at 11:56 PM ---------- Previous post was at 11:50 PM ----------

What about the Razor ground force? ...throw some bigger tires on that with a new power system... I should be able to fit in it (I am quite small). Someone on craigslist is selling one for 175$ which is pretty steep but oh well...

---------- Post added 04-17-2016 at 12:32 AM ---------- Previous post was 04-16-2016 at 11:56 PM ----------



If anyone on here knows of any cheap, lightweight go kart frames please let me know!!!
Ben

To the fact that you can get razor motors on amazon for around $70-$200, that is overpriced. Not to mention that razor motors are not good in general

 

[JokerBen321]

Alright. Thank you everybody. So Ill look into washing machine motors, but aren't they AC? Or is there an AC/DC(hehe) converter inside the washing machine? I have a new budget ~$700, so if I could get yalls advice on what to do with that (assuming I get a rolling chassis from craigslist for around $150). I want to have good acceleration and around 25-30 mph.

Thanks again,
Ben.

 

[itsid]

washing machine motors are universal motors (can be powered by ac or dc)
since they're cheap to make.. they're also too weak to power a go kart!
yeah ... I know he said that... it's still BS!

the belt drive on a typical wahing machine has a reduction ratio of roughly 23:1
to move maybe 20lbs at 1400 rpms...
to get down to the rotational speed of a kart axle you need ~54:1 .. and that'd only move ~50lbs

Sorry NotSoMasterMind;
but basically all you said in regards to motors is just misleading (not to say plain wrong)..
washing machine motors these days are generally incapable of powering a go kart;
and razor motors (razor DO NOT make motors at all... IIRC they use UNITE motors)
Unite motors are good, in fact for the price they're great!
a hundred bucks for a kW of reliable mechanical power is yet to be beaten.
but truth is.. if you stick a 120W version on a 200lbs anything it just won't do and fry on the spot.
And if a chubby adult is trying to get going on a KIDS TOY (that what most razor scooters and karts are in fact) they will be disappointed to say the least.
For what they are they're good...


'sid

 

[JokerBen321]

Okay then, so i dont get a washing machine motor... For a final budget of $700 what motor/esc should i get? I weigh 100 lbs, 30lbs in batteries, 50lbs of metal kart.... Top speed of 25-30mph and i want the back tires to chirp when i floor it (not a requirement i just want this thing to scoot)...

---------- Post added at 01:33 PM ---------- Previous post was at 01:30 PM ----------

I am trying to find a cheap 5000w motor, but I just can't find any, if someone finds a place that sells cheap high wattage motors, please let me know!!

 

[itsid]

well Ben, I linked the math thread above..
do it then!

once you figured out the approximate wattage you'll need we can see what options you'll have

'sid

 

[JokerBen321]

After spending about half an hour trying to figure out the math and getting almost a complete understanding of it, my final watts was either 1100 or 3900... On the final equation it said 9m/s^2 and I didnt know if I should square that number or just put my number (I used 13). So 1100 is just using 13 and 3900 is using 169.... 3900 makes more sense IMO because I used 3m/s as my acceleration and 13m/s as my top speed. But since my estimated total weight was only 90kg, it helped bring some figure down .

So I think a 5 hp motor should suffice right? I may occasionally have my sister ride in it which would add a whopping 52lbs so it shouldn't be too bad. a 5 hp motor is only like 3750 watts though right? So... maybe it isnt enough? I found a 4.8hp winch motor on ebay for around $150 which doesnt seem like a bad deal... i just dont know what controller i would use for that...

 

[itsid]

After spending about half an hour trying to figure out the math and getting almost a complete understanding of it, my final watts was either 1100 or 3900... On the final equation it said 9m/s^2 and I didnt know if I should square that number or just put my number (I used 13). So 1100 is just using 13 and 3900 is using 169.... 3900 makes more sense IMO because I used 3m/s as my acceleration and 13m/s as my top speed. But since my estimated total weight was only 90kg, it helped bring some figure down .

So I think a 5 hp motor should suffice right? I may occasionally have my sister ride in it which would add a whopping 52lbs so it shouldn't be too bad. a 5 hp motor is only like 3750 watts though right? So... maybe it isnt enough? I found a 4.8hp winch motor on ebay for around $150 which doesnt seem like a bad deal... i just dont know what controller i would use for that...

Nah it didn't (not if we talk about the same "final" equation...)
that was:
Pm = m * g * Cr * v + 0.5 * Da * Cw * A * v³

and that last part is speed cubed! (i.e 13m/s * 13 m/s * 13 m/s = 2197 m³/s³)

So yeah if that's the equation you played with I think
150 kg * 9.81 m/s² * 0.02 * 13 m/s + 0.5 * 1.2 kg/m³ * 0.7 * 0.9 m² * (13 m/s)³ = 1213 Watts
is closer to a good guess...

if you want somthing in that range.. larrylee is currently selling a capped golf cart motor with ~1500 Watts (old 2hp rating...)

and that should do the trick indeed.
http://holland.craigslist.org/for/5565452591.html

Here is he using a similar motor on his reverse trike
(I'd swap the old mechanical control against a newer electronic control.. it's much safer )

'sid

PS I'm do not know Larry other than from above linked thread,
so keep in mind that you should treat that CL deal as any other CL deal with an unknown seller

 

[JokerBen321]

Alright ill look into that motor. But so you think anything in the 2hp range should give me enough oomph? There is a 2.5hp 2000rpm motor from some surplus website, is 2000rpm enough? Not sure what others are... If i do go for this 2.5hp motor what controller would I use? I am only entertaining other ideas because i live in Florida and dont plan on driving up to holland any time soon . And if i find a steal of a deal on a 5-ish hp electric motor, would it like rip my face off? If i can get one that would add extra fun .

THanks Again

 

[itsid]

First electric motors should be rated in Watts.. NOT hp!
(luckily that got common a few decades ago )
Forget EVERYTHING you read about horse powers if you deal with electric motors.

A 1500Watt (~2hp) electric motor for ev application will outperform EVERY 5hp petrol engine any time!

rated rpms are a piece of string!
Sometimes the lower rpm rating is a gift, sometimes it's nothing but a curse.. depends on the torque rating and the application.

and for the controller.. how can we tell what controller you should use if we know nothing about the motor in question?

Ben, excuse me.. but this is getting a bit tedious....
you throw some random numbers at us, and we should do the guesswork.
It's like talking to a 14 year old with a nasty hunger for speed and no idea what he's up to...

So let's settle some "rules" for further communication, shall we?

If you want to ask about a certain motor, controller or anything.
SHOW US THE PART! Link to the source, so that we can see.. or post it's FULL specs!
Voltage rating, power rating, application, type of motor.. target application .. that sort of stuff.

Do the research.. look for motors MEANT for electric vehicles
since those are indeed rated for constant power output, and not just amperage they drain.
And those are guaranteed to be able to be speedcontrolled with a matching controller (and a matching controller will exist)

Yes, you can DIY a controller for nearly ANY motor out there, but the question is have you got the time, money and skill?
If you doubt that yourself.. stay clear from anything that you cannot positively identify as a motor made for electric vehicles.
(when in doubt.. leave it out!)

Sorry.. that might sound mean, but it's simple:
I might be able to tell if a particular motor can be used or not (or at least make an educated guess)
but it's immensively time consuming to find the necessary informations for any given motor to do so.
So you need to do your own legwork helping us to help you.

Maybe you should start googling for complete sets for now..
kellycontroller.com has some motors listed and is a great source for controllers as well.
There are dozens of "ebike" websites offering sets up to 20kW (~27 hp)
Google around, and see what's out there (and what the pricetags are...)
Pick what suits you best, and we can maybe go from there.

But personally.. I will not answer any question about "is that piece of string long enough"
without it's specs and a picture of it.

'sid

 

[JokerBen321]

https://www.surpluscenter.com/Elect...-MOTOR-IMPERIAL-ELECTRIC-P66SR274-10-2357.axd

That is the "2.5hp 2000rpm" motor I was talking about... My bad, I made the assumption that 1hp ~700-ish watts and that I didn't need to convert to watts whenever I commented on this forum. I understand that electric motors are measured in watts but going from hp -> watts seems easy to do so I didn't feel it was necessary...

My comment on "will a 5hp electric motor rip my face off" was about electric motors... I know electric will out preform gas to some extent, at least in the torque department(I own en electric car...).

I will look into kellycontroller.com and pursue this 2.5hp...whoops...1864w motor.

 

[itsid]

Ah see. a motor that's only rated in hp today ... fishy inconsistent BS I say...
Anyways, it seems to have a plausible rating at least
(36V 65Amp ~80% efficiency.. 1872 watts ... so far so good)
unfortunately I don't see a datasheet on the manufacturers home page...
that's too bad.. I can't tell if that's MAX power or continuous power (biiig difference)
it says it's also made for electric vehicles.. that's a good sign!
a 3/4" keyed straight shaft is also a very neat addition (you can get nice sprockets from any minibike/kart shelf)
PMDC controller with ~100 Amps is easy to find
http://kellycontroller.com/kds36100e100a24v-36v-mini-brushed-controller-p-270.html
(see that easy )

So, yeah haven't seen that motor in action, cannot find the datasheet.. sooooo it's a wild guess but it SHOULD work fine!

But if that's the max rating (it shouldn't.. but then it should be a watt rating as well)
you'll be extremely disappointed.
(and the old 2hp cart motor is the better option with a continous rating of 55Amps or ~1.5kW of continous mechanical output power)

Oh.. watt is real world.. hp is fictional!
german hp are different from bhp are different from (gasoline-)hp are different from (electric-)hp...
there are at least five different ways to define a horse power...
to be on the same page, let's stick with non fiction wherever possible

That being said.. a ~7kW truck starter does this to a go kart:
http://www.youtube.com/watch?v=C5lp3fP1WKo



'sid

 

[Poboy kartman]

Ah see. a motor that's only rated in hp today ... fishy inconsistent BS I say...
Anyways, it seems to have a plausible rating at least
(36V 65Amp ~80% efficiency.. 1872 watts ... so far so good)
unfortunately I don't see a datasheet on the manufacturers home page...
that's too bad.. I can't tell if that's MAX power or continuous power (biiig difference)
it says it's also made for electric vehicles.. that's a good sign!
a 3/4" keyed straight shaft is also a very neat addition (you can get nice sprockets from any minibike/kart shelf)
PMDC controller with ~100 Amps is easy to find
http://kellycontroller.com/kds36100e100a24v-36v-mini-brushed-controller-p-270.html
(see that easy )

So, yeah haven't seen that motor in action, cannot find the datasheet.. sooooo it's a wild guess but it SHOULD work fine!

But if that's the max rating (it shouldn't.. but then it should be a watt rating as well)
you'll be extremely disappointed.
(and the old 2hp cart motor is the better option with a continous rating of 55Amps or ~1.5kW of continous mechanical output power)

Oh.. watt is real world.. hp is fictional!
german hp are different from bhp are different from (gasoline-)hp are different from (electric-)hp...
there are at least five different ways to define a horse power...
to be on the same page, let's stick with non fiction wherever possible

That being said.. a ~7kW truck starter does this to a go kart:
http://www.youtube.com/watch?v=C5lp3fP1WKo



'sid

Close.....American BHP is Brake Horse Power. In Germany, it's BPH....Beers Per Hour....not to be nitpicky....