Go kart project advice

[tome]

I have a chassis (see pic) and want to turn it into an electric kart over the winter. I am just getting started, have read a bunch and talked with friends but am looking for as much input as possible. I would like it to be switch selectable to go at a slower speed (<15, say) for my 10 yr old, but be fun for older kids (my 20ish nephew and myself), looking for a speed of at least 30-ish at the high end. I was thinking of putting a Golden Motor 5kw bldc motor and controller on it and perhaps a lipo battery pack. What kind of speed could I expect from a motor like this? Also, is it possible to have the controller limit the speed with a switch?

I may buy or build a lipo battery pack. If I build one I want to have a bms on the cells so charging, etc., is less manual - don't want to disassemble things for charging/balancing as I see some people do. Any suggestions of bms options would be appreciated. I have read many(most?) of the threads on battery builds on the forum. Any other links to building lipo battery packs? One thing I was curious about is that I see most people solder to the battery. Are there tutorials on how to spot weld to batteries? It looks like tabs are sometimes spot welded on but I am not sure how one would do that. I have access to a spot welder though I don't know if this one is capable of doing it (depending on settings and how it is actually done).

I also found this differential axle that I was thinking would be nice vs the single piece that is on there now, though I am not really sure how to mount it yet. http://www.northerntool.com/shop/tools/product_35768_35768

Thanks,
Tom

 

[SlyCayer]

Good choice of a project...

The speed is a factor you asked about, but didn't mention "torque" do you want crushing and tire burning torque or want it to accelerate like 5hp honda motor would?

The controllers normally accepts tuning, you could always set yourself a half throttle switch that would cut the throttles inputs of ohms in half only giving half speed and half torque to your younger drivers...

 

[Arlo1]

Here is mine. [youtube]Mvm6WN7DWY8[/youtube]
And a one handed video with my old shity iphone [youtube]rQOZrGdRtOU[/youtube]
If you want any good power you will need to use a brused motor. You can go brushless but for big power it is huge money!
Im running a 500 amp 50v controller and 3 4s packs in series and 6 in parallel of 5ah lipo for a total of 1332 wh of energy with 900 amps and ~45000 watts available from the battery.

 

[tome]

Good choice of a project...

The speed is a factor you asked about, but didn't mention "torque" do you want crushing and tire burning torque or want it to accelerate like 5hp honda motor would?

The controllers normally accepts tuning, you could always set yourself a half throttle switch that would cut the throttles inputs of ohms in half only giving half speed and half torque to your younger drivers...

I want somewhere in between. I don't want to burn the wheels off or pull wheelies but do want zippy accel.
Thanks for the,response.
Tom

 

[tome]

If you want any good power you will need to use a brused motor. You can go brushless but for big power it is huge money!
Im running a 500 amp 50v controller and 3 4s packs in series and 6 in parallel of 5ah lipo for a total of 1332 wh of energy with 900 amps and ~45000 watts available from the battery.

Arlo1, I had seen your thread in the forum and your cart looks like fun. I don't want/need torque to tip mine over though What motor are you using?

Thanks for the info,
Tom

 

[Arlo1]

Thats a 6.7inch series wound brushed motor from a golf cart. They are pretty common. They can be found in golf carts and forklifts. The youtube video with the 70,000 watt kart has the same motor. It weighs 43lbs
You can find lighter permant magent brushed motors which will make about the same power as my video. I can put about 3x the power I am into my motor and I plan to eventualy. You can look for a agni 95r or something smaller and lighter if you dont want the power I have.

 

[tome]

Thats a 6.7inch series wound brushed motor from a golf cart. They are pretty common. They can be found in golf carts and forklifts. The youtube video with the 70,000 watt kart has the same motor. It weighs 43lbs
You can find lighter permant magent brushed motors which will make about the same power as my video. I can put about 3x the power I am into my motor and I plant to eventualy. You can look for a agni 95r or something smaller and lighter if you dont want the power I have.

Yikes, that is crazy fast. Definitely don't need that kind of acceleration/torque. The Agni 95r seems to be quite pricey, $1500-ish. I much prefer $450
Thanks again,

Tom

 

[Arlo1]

Thats a 6.7inch series wound brushed motor from a golf cart. They are pretty common. They can be found in golf carts and forklifts. The youtube video with the 70,000 watt kart has the same motor. It weighs 43lbs
You can find lighter permant magent brushed motors which will make about the same power as my video. I can put about 3x the power I am into my motor and I plant to eventualy. You can look for a agni 95r or something smaller and lighter if you dont want the power I have.

Yikes, that is crazy fast. Definitely don't need that kind of acceleration/torque. The Agni 95r seems to be quite pricey, $1500-ish. I much prefer $450
Thanks again,

Tom

Yeh there is a lot of good motors you can find ~$450 im not up to the current good deals. I know the motor I got cost me ~$20 and thats just because i have to replace the bearings. When buying a motor make sure you know what controller you need and the price of it!

 

[whatever]

there are 48v brushed motors ( with magnets) and gear reduction drive can bought in china very cheaply ( $30 to $40 usd)
some use motorbike size chain, you would have to search aliexpress to find them, can run on a $20usd brushed 500watt controller
( keywin) would zip you around cheaply

 

[whatever]

something like this
http://www.aliexpress.com/product-fm/395846835-Promotion-Gift-in-free-Tricycle-Motor-and-Controller-brushless-motor-48VDC-350W-wholesalers.html

that one is 350watt a 500watt would be better, its a little overpriced but not too bad

 

[whatever]

try this page its got a good list of suitable motors,
it has 500watt and larger ones
http://www.aliexpress.com/store/group/Tricycle-Motor-Controller-other-Parts/601157_209920937.html

 

[whatever]

those motors in link above have planetary gear drive in one end of motor,
so torque on take off would be pretty good,
they are commonly used in smaller trikes in china which you can carry goods or a couple of people
I had a couple of those trikes, they are quite good not too fast but torque is good,
your wheels are pretty small so you might not require a reduction drive.........not sure

 

[whatever]

this one has no reduction drive
http://www.aliexpress.com/store/product/Dirt-Bike-Motor-48VDC-750W-DC-Motor-with-CE-appliance/601157_318726192.html

 

[whatever]

or go brushless
http://www.aliexpress.com/store/209533

 

[whatever]

this one is cool, whole rear diff with motor
http://www.aliexpress.com/store/product/72V-1500w-electric-tricycle-conversion-kit/209533_511215265.html

enough from me

 

[tome]

Hey whatever ( heh, I said "whatever"), Thanks for the suggestions and links! I'll take a look.
Tom

 

[whatever]

no probs I was surprised how easy it was to find so many different motors in short time

 

[Arlo1]

no probs I was surprised how easy it was to find so many different motors in short time

Can you find any bldc without gear drives on them?
And has anyone tested these motors? I would like to get something thats been tested a bit.

 

[whatever]

that is a bit harder! brief search really only came up with goldenmotor has some,
successmotor also does them but too pricey, will post if I find cheap source

 

[winchmeup]

have you thought about running a torque converter. This could allow you to run a slightly smaller motor (contoller etc) and still get good acceleration. i just put a post in ebike general discussion about this. (dont know how to place link)

I have been stuffing around with a turnigy setup for my kids. Still havent got anything great to report but i have been keenly following the ebikers quest.

I recon if we can get 5kw with one of these in a light frame it should go pretty well.

 

[Arlo1]

have you thought about running a torque converter. This could allow you to run a slightly smaller motor (contoller etc) and still get good acceleration. i just put a post in ebike general discussion about this. (dont know how to place link)

I have been stuffing around with a turnigy setup for my kids. Still havent got anything great to report but i have been keenly following the ebikers quest.

I recon if we can get 5kw with one of these in a light frame it should go pretty well.

Torque converters add complexity and reduce efficiency, As a rule with electrics any weight added to a drive system for somehting like a tranny could be replaced with a bigger motor for the same performance and less complexity and less stuff to break.

 

[winchmeup]

Thanks Arlo
Jeremy had said pretty miuch the same thing in the general section
Oh well just a thought
Steve

 

[2moto]

this one is cool, whole rear diff with motor
http://www.aliexpress.com/store/product/72V-1500w-electric-tricycle-conversion-kit/209533_511215265.html

enough from me

40kg! Yikes!

No need for a diff in a Kart.

 

[Arlo1]

Thanks Arlo
Jeremy had said pretty miuch the same thing in the general section
Oh well just a thought
Steve

I have a few 6.7inch brushed series wound motors now and 4 controllers to run them it is amazing what 500 amps and 50 volts can do with one of these.
If I was you I would use a motor like that because they are easy to install and easy to find and controllers are cheep! Then if you want more later you can just up the power most of the 6.7 inch brushed motors I seen are good for over 100v and ~600 amps thats huge power!

 

[winchmeup]

Good advice arlo
maybe for my next project. it would be a bit OTT for my little cart. Its just over a metre long and weighs about 10kg if that. Basically a mini quad bike chopped, stretched and a plastic school seat fitted.

steve