Finding a Motor!

[Camn]

Hey everyone,

I'm new here but I've been reading allot of threads lately about electric karts, yet I haven't really been able to figure a few things out.

I just bought an old go kart which is surprisingly electric already! The problem is it has a 24v wheelchair motor on it (0.5HP 3300RPM), and it goes way to slow for me. It is obviously not geared very well either because you need to push it to get it going, and after coasting for awhile it maxes out at about 15 km/h.

So I want to get more power; and reading the many forms on this subject have led me to believe I need a motor in the KW range. I actually found a used golf cart motor and a controller for $150 bucks on craigslist, but it turns out the guy already sold it and just forgot to take the listing off, what a letdown!

I have been searching around for a while since and haven't been able to track any more down. I don't have allot of cash for a motor (like $250 is my max). I have noticed many cheap scooter motors online and tracked this one down:

http://tncscooters.com/index.php?route=product/product&product_id=344

Here are some specs on the cart:
-Solid metal frame (fairly heavy I would guess about 80lbs without the motor)
-Freewheeling back tires (I want to mount the drive sprocket on one of the tires)

So my question is, have any of you guys had any luck with using scooter motors in your karts? Do they have enough torque and power, and what speed can you get out of them? Or should I spend the cash and try to track down a golf cart motor?

I want to be able to cruise around on fairly flat roads at about 40 km/h.

Thanks,

Cameron

 

[landuse]

to the forum Camn. Not too many of us are knowledgeable about electric motors, but someone will give you some info soon. Just hang tight. Why don't you post a pic or two of your kart

 

[Camn]

Yep I was just about to do that actually! Here they are, its not beautiful but i think it's got potential!

 

[Fallenleopard]

Hey just a few tips

That motor is a good size and within your budget. What you need to look at now is the voltage and amp draw that the motor will have on the batteries. I don't know the current condition or voltage of your battery's but you may need to purchase new batteries to suit the motor.

Speed and torque will be Dependant on your gearing as well as the motor. The current gearing may be fine. You can check your speed using the speed calculator on this site.

I hope this helps a little.

 

[Camn]

Thanks for the reply,

I just purchased a 1000w motor from TNC Scooters. I also got a speed controller and appropriate sprockets and gears. I decided to get three different motor sprockets to experiment with the gearing.

Iv'e attached a pic of the options I have in terms of speed. I'm going to try to find a good balance between power and speed.

What is the max speed that I can get out of this motor?

Also I have been eyeing up some 35 amp hour SLA wheelchair batteries so I think I am going to get three of those and hook them up in series. Will this be enough power for a decent driving time (say about an hour)?

 

[Fallenleopard]

Thanks for the reply,

I just purchased a 1000w motor from TNC Scooters. I also got a speed controller and appropriate sprockets and gears. I decided to get three different motor sprockets to experiment with the gearing.

Iv'e attached a pic of the options I have in terms of speed. I'm going to try to find a good balance between power and speed.

What is the max speed that I can get out of this motor?

Also I have been eyeing up some 35 amp hour SLA wheelchair batteries so I think I am going to get three of those and hook them up in series. Will this be enough power for a decent driving time (say about an hour)?

By max speed do you mean have fast will the motor turn? That depends on the power of the motor and the gearing (not enough info to work that out not that I would be able to complete the calculation) the gearing once it is at the 3000rpm then that's the fastest it will go, is this what you mean? (If it even gets to 3000rpm)

You need to work out the amp draw of the motor if it draws 35amps per hour than your battery's will last 1 hour...
With an SLA there is a discharge curve unlike a lipo or other lithium battery. This is something you would need to consider as well.

Any more questions feel free to ask I will help to the best of my ability.

Sent from my Nexus 7 using Tapatalk 2

 

[Camn]

The motor is rated at 3000 RPM and it has a draw of 35.6 amps. These are the specs I got off the sitehttp://tncscooters.com/index.php?route=product/product&path=52_56&product_id=344
(Link above)

I was wondering about the speed of the cart. If anyone uses one of these what is the gear ratio you used and what kind of speeds have you been able to get?

Cameron

 

[Fallenleopard]

The motor is rated at 3000 RPM and it has a draw of 35.6 amps. These are the specs I got off the sitehttp://tncscooters.com/index.php?route=product/product&path=52_56&product_id=344
(Link above)

I was wondering about the speed of the cart. If anyone uses one of these what is the gear ratio you used and what kind of speeds have you been able to get?

Cameron

OK well if the motor has an amp draw of 35.6A then your battery's will not last on full speed for 1 hour, due to the discharge curve of an SLA battery. Maybe after 1/2 an hour you would notice the speed dropping (just an estimate all depends on other factors)

You just put up a table with speeds doesn't that give you a rough idea? Just put one of the sprockets on and run it if its not to your liking then change the sprocket. What you must also be care full of is the stress you put in the motor while taking off.
If your gearing is too high then stress will be placed on the motor and this could lead to more amp draw.

I can offer you an example but it was not a cart. With a group of people from school we created an electric bike the motor was 500w and we had 2 heavy 80amp hour batteries. (SLA) the bike at max speed went about 45km/h (this was in top gear) (total bike weight was about 50kg)

Obviously this is a different project but that I just an example to think about

Sent from my Nexus 7 using Tapatalk 2

 

[Camn]

Thanks for the info,

Ill just have to try it out and see how it works. If I could get 45 min of solid driving time I'd be happy with that, I can always upgrade the batteries down the road or add another set in parallel.

 

[Fallenleopard]

Thanks for the info,

Ill just have to try it out and see how it works. If I could get 45 min of solid driving time I'd be happy with that, I can always upgrade the batteries down the road or add another set in parallel.

Yeah just experiment with it

Make sure you get some photos and videos for us when thou are done!

 

[builder bob]

you might be able to use some large B grade R/C plane lithium batteries and use those. I don't know what the highest mah rating on a B grade aircraft battery is but I think I saw a 10000 mah A grade 4s for $60.

 

[Camn]

Hi all,

Finished this go kart and it runs pretty well! I got a top speed of 28 km/h on flat roads and it has enough power to go up a fairly steep hill. The batteries last for over an hour of driving.

It's still missing a brake which I am installing now. I blew two tires already on corners so I am trying to find some thicker ply tires. Maybe wheelchair tires?

Here are some pics of the finished product. I added checker plate and battery boxes so I think its quite an improvement over the before kart.

Cameron