Space Kart - Project Updates

Automotive
#1

We are in week 2 of our 8 week group project to build an electric flat pack plywood gokart. A large part of the project is teaching everyone how to use Inventor, here is Frank leading the class today:

After evaluating the safe option of buying an off the shelf 1000 watt brushed motor with SLA batteries (which would be cheaper but much heavier and slower) or doubling up on motors, we decided to go for the more technically interesting brushless approach.

So far we have ordered 1 set of LiPo batteries(4x 10s 4000mah) and a brushless motor(120A 5kw peak) and controller from HobbyKing for a drivetrain cost of $581 w/ shipping. Here is a movie of what the motor looks like relative to a kart

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Remember that one time at Makerspace? A fill in the blank game
For sale, complete electric gokart, $400
#2

Wish circumstances had aligned for me to take this class.

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#3

Starting to rethink our use of airplane RC brushless motors / controllers for this application, they were really not designed for this application and I’m starting to think that we will just end up frying either the controller or motor when we try to propel a 300-400 pound gokart. A more appropriate motor controller (but 3x the cost) would be something from Kelly Controller

Turns out making an electric gokart for less than $1,000 will mean adjusting some expectations of what you would think of for a gokart, if we were shooting for for $2,500 we could have a decently performing kart, for example we could get the a Kelly kit and 5 kilowatt motor for $1,289 and then spend another 500-1000 on batteries. Or this brushed motor kit for $930

#4

Do you really even need $1k? Make magazine had a perfectly fun build of a gokart type vehicle that used cordless electric drills for motors.

#5

Ha, that is interesting but I think we want something more gokarty (more power!)


http://makezine.com/projects/drill-kart/

Part of the problem is defining a goal, the point of the class isn’t to build a racing kart, but to learn to use Inventor along with building the kart we design in Inventor to make things interesting.

#6

I was at the meeting last Saturday for just a few minutes. I have a 15,000 Watt Motor Controller that I am willing to donate to the Kart project. I plan to bring it to the space on Tuesday, 6/9, and leave it with one of you guys. It is currently mounted to a Traxxas XO-1 car chassis and has a Castle 1717 motor plugged in, so I will plug in a Spektrum radio receiver so that you can do some testing of the controller. Here’s a pic of the controller I am talking about.

Turnigy_Dlux_250A_60V_ESC.png572Ă—826 512 KB

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#7

Quick question about the LiPo batteries you have ordered. Did you also order a battery charger that is capable of balance charging a 10s LiPo battery?

#8

The lowest cost, 10S capable Lipo charger on the market is the iCharger 3010B.

A-Main Hobbies has them for $189.99 with free shipping. You can also use discount code “JUNE1250” to get $12.50 off.
http://www.amain.com/rc-cars/junsi-icharger-3010b-lilo-lipo-life-nimh-nicd-dc-battery-charger-10s-30a-1000w-jun-3010b/p195151

#9

treadmill motor?
https://goo.gl/bAlfNv

#10

Don’t have a charger on order yet, will need lots of accessories, I’m still on the fence on if we should return what I already ordered and go with a brushed dc motor setup

This looks like a potentially good route: http://evhelp.com/Electric_Go_Kart.htm also interesting because I just picked up the exact same tires from northern tool for $5 a piece

What would be the effect of running a treadmill motor that says its rated for 90 volts dc at only 48 volts? Would it just cut power output in half?

#11

Before you decide to go with a brushed DC motor setup, consider the power loss due to how inefficient a bushed motor is compared to a brushless motor. Here is a chart comparing the two motors…

#12

I am teaching a class on how brushless motors work on Sunday, June 21.

Here’s a link… RC101 - A class on How Brushless Motors Work - Sunday, June 21

#13

Well apparently the cult of the brushless :smile: has started its proselytizing for small children s ride-on toys.

Kid’s electric mini goes brushless, pops wheelies

Sad, that he does’t apparently trust his kids with throttle control…

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#14

I hope the tires you buy for the Space Kart are rated for 100+ miles per hour! This kart is going to need them.

#15

And that, friends, is “throttle on understeer”, in case anyone needs a good demo.

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#16

That car definitely needed a differential on the rear axle. If you go with a solid axle the car will push like a dump-truck throughout the turn. Another alternative is to put drifting tires on the kart, then it will drive like these tricycles in the video below…

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#17

Does anyone have a 1000w 36v DC powersupply laying around to power the 3010 1000w charger?

http://www.amain.com/rc-cars/junsi-icharger-3010b-lilo-lipo-life-nimh-nicd-dc-battery-charger-10s-30a-1000w-jun-3010b/p195151

I’m thinking of only getting the 10A 300W charger instead so I can just use a pc desktop power supply I have laying around. Has anyone tried parallel charging before? Could only do 0.5c if attempted to parallel charge all 4 lipos

http://www.hobbyking.com/hobbyking/store/__6609__iCharger_1010Bplus_300W_10s_Balance_Charger.html

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#18

Sorry. All the DC power supplies I have are 12V. I have a 12V 60A power supply pulled from a HP Server that I use when I need to pump more than 10 Amps through a battery charger.

#19

Well here is another possibility, with plans available from my favorite maker store; United Nuclear

The plans are between $20 and $40 depending upon which size engine you pick. They also have a nice video of the engine on a home made go cart:

#20

@artg_dms This is the meter I was telling you about during the Brushless Motor Class on Sunday. One end will plug into the LiPo battery and the other end plugs into the ESC. Then it will give you all the power diagnostics while you run.

http://www.powerwerx.com/_images/products/Watt-Meter-PP_lrg.jpg