Go cart build thread (in support of controller build)

I've been posting some questions about various things and was suggested to make a build thread, so this is what it's all about:
I want to build a brushless controller.
I will be building a go cart as a test platform for my controller.
The motor I have in mind is the ME0907, so I will be building the controller to meet the needs of that motor (or maybe I will build it overkill to work with bigger motors)
so, here's the cart I bought (50$):

The only upgrades I have planned for the cart is to cut it in half and add a couple of feet to make it human size, and install a live axle (and brakes I suppose).
The plan is to use heavy, crappy, inefficient lead acid batteries from walmart because they're cheap. If the controller works out, I will redesign this whole thing using sleeker technology, maybe a new cart, or a bike, or quad, or car. don't know yet.
So, opinions? am I wasting my time trying to make a high power brushless controller?
is my cart too shitty to make a viable electric vehicle?


EDIT: liveforphysics bitch-slapped my brushless idea, so I am now leaning towards making a brushed controller
http://endless-sphere.com/forums/viewtopic.php?f=14&t=32199&start=15

Are you wasting your time building stuff like this? Never.

Go for the cheap lead acid to test your controllers - this is a good move economically. As you say, once it shows promise, go for something more powerful and lightweight.

OK, brushless controllers - there is a huge market for these things. One of the biggest gaps I can see a need for filling, is high power, lightweight electronically commutated motor controllers. I say electronically commutated, because brushless motors are really just AC motors - three phase AC motors in 99% of cases. I'm shopping around for a decent three phase, high power, medium voltage (300 to 500 V) permanent magnet AC motor controller in the 100 to 160 kW range, that weighs less than 10 kg and isn't the size of the bike it's being fitted to. Seems there is a lot of stuff well below, and well above, or system voltages of 24-100 V or 500-700 V, but not much in between. There are exceptions, but these are all in the development stage. So yeah, this is a big development area.

Brushed DC motor controllers are a bit easier, but again, they don't seem to exist after about 120 V. If you want to run a ~100 kW motor or pair of motors, you will have some seriously high currents in the leads. So a brushed motor controller capable of system voltages 300-400 V would be ace too.

So that's my wish list :lol:

All the best with it mate! And make that $50 POS frame wince with the power it will soon experience!

jonescg said:

So a brushed motor controller capable of system voltages 300-400 V would be ace too.

Click to expand...

http://www.evnetics.com/index.php/products
http://www.cafeelectric.com/shop/index.php?main_page=index&cPath=1
Maybe others.

Well, looks like I'm committed to brushed DC for now. just bought a motor:
http://www.ebay.com/itm/280741777753?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649#ht_500wt_959

Mars ME0709 slightly used 380$

PS. Many thanks to liveforphysics & amberwolf for probably saving me a bunch of heartache trying to design a high power brushless controller without sufficient experience.

When you do move up to the brushless type, I'd recommed first working out higher power variations of something very simple, like Jeremy Harris' version based around the MC3303x chips. There's a thread around here somewhere with all that stuff in it. (FWIW, that's one of the chips I tried working with, and failed to even get a bench version of the appnote circuit going of, because of layout problems).

amberwolf said:

When you do move up to the brushless type, I'd recommed first working out higher power variations of something very simple, like Jeremy Harris' version based around the MC3303x chips. There's a thread around here somewhere with all that stuff in it. (FWIW, that's one of the chips I tried working with, and failed to even get a bench version of the appnote circuit going of, because of layout problems).

Click to expand...

Sounds like a plan; will do, when the time comes.

Got my motor in the mail today. I think I believe the ebay seller when he says he only ran it for 30min total. zero groove in the stator, zero dust in the motor, and the brushes are not even broken in. came in the original packaging. I tried testing it with a 12V 5A power supply but it didn't do anything, which is to be expected, but I wish I had something to test it so I could see it turn. The terminal resistance is .06 - .12 ohms depending on position, but the average is .09 ohms

strantor said:

I tried testing it with a 12V 5A power supply but it didn't do anything, which is to be expected

Click to expand...

I agree it is to be expected for most motors. Even a little RC-model motor may need more than 5A to be able to start.

I read the Agni can be run on two R6 batteries, so you could try that, but I think that may be something that only an efficient motor like the Agni can do.

strantor said:

... I wish I had something to test it so I could see it turn.

Click to expand...

Car battery?...

Just don't let it overspeed - a quick spin and that's it, or connect it to a fan or some other mechanical load.