E-Kart

[jkv357]

My son and I have been working on an electric racing kart for a high school competition.

We got it going the other day for the first time and hit 34 mph on our 35 mph gearing. For the competition it will be geared closer to 45 mph.

It uses a Mars ME0909 motor, Alltrax SPM 48400 controller and 3) 12V batteries in series for 36V. 75# of batteries and 25' of cable.

Still need to finish a roll cage for it.












Jay

[ecomodded]

What blast (on a closed course) your cart must be.
It looks very professional, is it made from a modified gas sucking go-cart ?

[jkv357]

Originally Posted by ecomodded

What blast (on a closed course) your cart must be.
It looks very professional, is it made from a modified gas sucking go-cart?

Yes. The frame is a "Trick" (now "Trick Olympic") brand 4-cycle kart. The chassis and fairings were donated for the project.

Our work so far involved designing and fabricating a mount for the motor and a system to securely support 75 pounds of batteries.

A roll cage of 4130 chrome moly tubing still needs to be completed.


Jay

[sendler]

Excellent! Are there races? Formula class for the electrics?

[jkv357]

Originally Posted by sendler

Excellent! Are there races? Formula class for the electrics?

The Electrathon (Welcome to Electrathon America) is a national competition with regional events.

Although we tried, we couldn't complete our vehicle for this year's final competition at Road America, held today. The 4130 chrome moly tubing we ordered for the roll cage was delayed, and I still don't have it...

Here's a photo of the start of today's Electrathon competition - (attachment below)

[sendler]

Originally Posted by jkv357

Here's a photo of the start of today's Electrathon competition - (attachment below)

Oh yeah. Electrathon. Modern soap box derby. I studied the art form when my daughter's high school bought a chassis. They never found the money to do anything more than look at it.
.
To Bad the electrathons got totally rained out from even showing up on the Saturday I was competing at Watkins Glen. I was looking forward to checking them out. World champ C. Michael Lewis was there navigating in a diesel engine swap Insight. He didn't bring his electric.
.
How much loss is there in a wide open controller? One idea I had would be to set your wide open gearing to the predicted average speed and have a boost button actuate a starter solenoid which would by-pass the controller whenever there was no traffic to eliminate the heat loss.

[jkv357]

Originally Posted by sendler

How much loss is there in a wide open controller? One idea I had would be to set your wide open gearing to the predicted average speed and have a boost button actuate a starter solenoid which would by-pass the controller whenever there was no traffic to eliminate the heat loss.

Thanks. My son is going to look into that.


Jay

[sendler]

The live axle and sticky tires are also a little less than efficient in the turns but it will still be a blast to run and get it dialed in as good as it can be.

[Daox]

Looks like great fun there. Too bad you don't get to compete. Next year?

[jkv357]

The kart set-up does have a few drawback, which we have tried to address. The solid axle does scrub when turning, but we have thinner tires at a higher PSI to help reduce it as much as possible. It's very noticeable when turning tightly, but the steering geometry is designed to pick-up the inside rear tire to let it scrub less, and we've moved the rear wheels in as far as we can as well. Fortunately the turns are huge and it shouldn't be too big of a handicap. We fitted the motor with a custom clutch so it will coast freely, and it seems to coast very well. There were only 2 cars that carried any amount of cornering speed - the overall winner and the fastest car. Most were very slow in the corners, but with spoked bicycle front wheels you couldn't push too hard. I did see a car in the pits with one of its front wheels folded over. Our theory is to keep corner speeds way up in order to help conserve energy - that's the theory...

The other plan is to P&G on the straights. Bringing it up to max speed (45 MPH @3000 RPMs) and coast down from there. Not sure how far would be the best to coast down to though before full power back up to 45 - maybe 35 MPH?

He really just wants it to be one of the faster cars and not compete for overall honors. Overall honors includes the quality of your monthly and final reports and also requires we add 60 pounds of ballast to compete in class. We will most likely just run Exhibition Class and not worry about some of the overbearing rules.

They have 2 other events besides the RA one. Pretty sure they are both at stockcar tracks. Some of the Electrathon cars have suspension, which would be nice at at least one of the tracks because of the bumpy surface.

I just picked up the roll cage tubing today, and we will continue to work on getting the car completed for the first event after school starts later this year.

Thanks for the compliments and tips.


Jay