Electric go-kart?

[weetsie]

yeah i know this is in the aircraft section but i don't know where else to put it, sorry, feel free to move it.

HXT_80-100-A_180Kv ( http://www.hobbyking.com/hobbycity/store/uh_viewItem.asp?idProduct=5139&Product_Name=HXT_80-100-A_180Kv_Brushless_Outrunner_(eq:_70-55))

i want to put one of these in a go-kart and use as close to the 7kW as possible giving me 5-10HP?

I'm thinking of using 2-4x12V-24V 75A car/deep cycle batteries giving me 48V/150A.

i work that out to be 180kV * 48V = 8640RPM and closer to a 5.5HP go-cart engine than the 130kV version so i can just put it directly in place of the gas engine without replacing the sprocket.

that's also 7200W of power?

obviously that's all @ 100% efficiency of every component, I'm hoping to get 75% efficiency in the end.

so if i use a servo tester linked to the acceleration pedal all that i need to sort out is the speed controller right?

ive seen 150A speed controllers but they they weigh 50-150grams so they could do with being a bit more beefy for a go-cart and they wont work with car batteries will they?

so, if you could tell me how close i am with my calculations/thinkings and what i can do about a speed controller? i can follow schematics so long as its resistors and capacitors not 30 pin IC's.


thanks

[Fluffy Monster]

(Cheap) Speed controllers that have a linear response are a little rare. You may find your Kart has two speeds. On or Off :D

[DeUglyOne]

I'm thinking of using 2-4x12V-24V 75A car/deep cycle batteries giving me 48V/150A.

ive seen 150A speed controllers but they they weigh 50-150grams so they could do with being a bit more beefy for a go-cart and they wont work with car batteries will they?

Volts and Amps is Volts and Amps... the controller could care less where they come from.

You, on the other hand, should. The hazards of using a wet cell battery to power a go-kart far outweigh the benefits you might see, let alone the size and weight problems you'll run into.

The ratings/reviews just under the ad in your link showed that it has been done, with a vid on YouTube: YouTube (http://www.youtube.com/watch?v=vwODx028_Jw)
Looks as if there a quite a few more there as well.

He's using 3 of the motors to power his, and take a good look at his battery pack - less than the size of one wet battery. Your best bet might be to see if you can contact him or one of the others shown and get some pointers from them.

[jeffs555]

You might have startup problems with the typical hobby ESC unless you have some kind of clutch. Most of them won't start with much of a load on the motor.

[weetsie]

You might have startup problems with the typical hobby ESC unless you have some kind of clutch. Most of them won't start with much of a load on the motor.

is that not something i could change with one of those cards that goes before the ESC?

[Chippie]

is that not something i could change with one of those cards that goes before the ESC?
A soft start setting mebbe?

[jeffs555]

The problem is that rc brushless motors and esc's are usually sensorless. The esc gets its feedback from the motor by looking at the current generated in the windings from the turning motor. The motor has to be running at some speed before it generates enough current feedback. At startup it runs open loop with no feedback which is why it is hard to get a smooth start and why they will not run smoothly at low speeds. Depending on the mechanical load on the motor it may not start at all which is why I suggested a clutch.

Most electric vehicles use sensored motors which have hall effect or optical feedback so they can smoothly start and run at low speeds irregardless of mechanical load. For using that motor with any EV, it would be best to add sensors and use a sensored controller.

Here is one place that talks about using the hobby sensorless motors and esc, but it they are talking about a moped where you can use the pedals to get it started. http://visforvoltage.org/forum/4054-holy-smokes-7000-watt-brushless-motor-controller-recommendations

[earlwb]

Since they alreadyt have some higher performance 20hp equivalent go-carts, it ought to be doable:
http://www.k1speed.com/karts.asp
Since they mentioned "dry batteries", I assume they are using large LiFe or LiPo cells.
they have a really nice digital electronics unit inside there for the motor control, including braking to recover energy too.

less powerful version:
http://www.electricgocarts.com/


You can get the parts for an electric scooter and use those in a go-cart. That would be a practical route to go. You can buy the motor and speed control unit with throttle. of course some embed the motor into the wheel, so you might have to research that some to get the external motor versions.

This guy has some ideas on how to do it here too:
http://www.instructables.com/id/Gas_to_Electric_GoCart_Conversion_150cc_2_seater/
As he did it to his go-cart.
another one here:
http://zedomax.com/blog/2008/09/25/diy-how-to-make-an-electric-go-kart-or-is-it-go-cart/

[Pete P]

Most websites which sell the larger-than-D cells NiMH will offer discounts for bulk purchases... Quite the potent pack can be made on the cheap!

[mjsas]

Here is a link to electric scooter parts:
http://www.electricscooterparts.com/
They have 1000 watt controllers for $55 and matching motors.
You might look at automotive engine cooling fan motors. Some of these are quite large and I have run them at 24 volts. Even at 24 volts they did not get hot or even very warm. Some of the Denso motors look to be in the 1000 watt range, bigger then the well known EV warrior motors, the Mark VIII fans also have very large motors.
Most electric scooters use SLA batteries so they should be safe and powerful.
Two 1000 watt motors should make a reasonable go cart.

[vintage1]

years ago when I were a 'prentice, the boys built one using a car starter motor and battery. Went like heck for about 3 minutes..

[earlwb]

I remember rigging up a mini-bike with a big electric motor. You would take the bare wire and touch it to the frame using a homemade lever on the handlebar. You basically had a go or no go power setup. We used two or three car batteries in series.
If I remember we had the centrifugal mini-bike clutch on it too, as the motor didn't have a good startup from stop torque, so the clutch allowed it to build up some speed first. Yeah there was arc'ing and spark'ing.

[JustinONE]

I think Astro flight sells E-bike ESC's and motors..
http://www.astroflight.com/index.php?main_page=index&cPath=20

[Ron W3FJW]

That stuff must be gold plated....

[Nightz]

Your better off with a Briggs permanent magnet DC motor (Etek) or equivalent. Pick up a golf cart controller. 4QD and Curtis make a controller that will work as well. Don't forget a nice big Mushroom button for an E-STOP. Put a snowmobile clutch/torque converter on it to get some RPM's before busting loose.

-Rocko

[gobigkahuna]

Don't know if this will help, but I ran into these at All Electronics while shopping for something else:

http://www.allelectronics.com/index.php?page=search&search_query=scooter&x=0&y=0

[fizzit]

Most websites which sell the larger-than-D cells NiMH will offer discounts for bulk purchases... Quite the potent pack can be made on the cheap!

Gaaaaah! I have been searching all over the internet! Where do you find these huge NiMH's???

[Ron W3FJW]

http://www.all-battery.com/ni-mhbatteries.aspx

F size batts. Up to 14ah.

[earlwb]

They also have some lower power speed controls for the scooters too.
http://www.allelectronics.com/make-a-store/item/MSP-150/24-VDC-40-A-MOTOR-SPEED-CONTROL/1.html
Uses a 50k ohm potentiometer for the throttle.

[fizzit]

http://www.all-battery.com/ni-mhbatteries.aspx

F size batts. Up to 14ah.

Oh, OK thanks. I was hoping for rectangular batteries. I have seen rectangular NiMH's before, they were small though. Much more efficient space use...

[Pete P]

Yeah, I got mine from all battery some time ago :D But the project wasn't mine, alas :C

Also, massive batteries:
http://www.powerstream.com/Ni-Prism.htm

http://cgi.ebay.com/ebaymotors/Toyota-Prius-7-2V-Nimh-Battery-Module-6-5ah_W0QQcmdZViewItemQQcategoryZ33574QQihZ002QQitem Z120403396485QQrdZ1QQsspagenameZWDVW