Off-Road Electric Build

AndyW

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My 13 year old niece and I started our build of an off-road 2 seat electric go kart today. It was originally going to be an electric build of a Spider Carts Grandaddy and then we decided to create our own plans. Our build takes inspiration from the Tao Arrow kart. I purchased the a-arms and spindles for the Arrow kart online. The kart is going to be powered by a Motenergy ME1507 with a Kelly controller. The kart will have 22” rear wheels so with the motor spinning at 3800 rpm the plan as of now is to install a jack shaft to get a gear ratio of 8:1 or 9:1. I want to limit the top end speed and have good acceleration. The battery will be constructed of 32650 cells in a 24S14P configuration for 72V and 70A. The plan is to build a metal battery box under the seats. We got a little bit of the frame base completed today. My niece today learned how to use a tube roller, a metal chop saw, a hole saw to notch tubing, and tack weld tubing. We are mostly only going to work on this on Saturdays so we expect this project will not be completed until late Summer.40025C52-73D9-4A75-A1E4-AC91AD67D714.jpegEAB7431B-E1AF-4041-9149-A7C229AF8B0E.jpeg086B35B4-850A-479C-912F-9D7593C66DE1.jpeg97981D7C-F953-4178-BAEA-B8025410ADFA.jpegC0E862B0-24CE-42AE-8208-2CA6ADD94B8A.jpeg
 

EpsilonZero

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That's a lot of kart and a lot of motor power! How much is it going to weight total?
 

AndyW

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That's a lot of kart and a lot of motor power! How much is it going to weight total?
It will be lots of kart so it needs lots of motor power. I estimated a 650 lb. gross weight. It will be the size of a 200cc or 250cc adult 2 seat off road go kart. My calculations for power based on weight, speed, and acceleration showed me I needed a peak power around 8kw. 200cc is 13HP or 9.75kw. Calculating for motor efficiency puts that down to just under 9kw. Smaller motors would get me to the peak power, but their efficiencies sucked when pushing them beyond their continuous power ratings. I also wanted a sealed motor. The ME1718 is limited to 100a so that put it just below the 8kw requirement. The final reason for going with a motor this big was that I wasn’t going to make the mistake of under powering the kart. I have read dozens of posts online of people complaining that they under powered their kart.
 
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I74

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That's going to be a great project & ''a lot of fun'' end result for you & your Niece !!
Very cool that she is getting right into it with welding & fab ect.
Excellent age to learn those skill sets,, & a real rarity with kids these days,, especially for a Girl. :)(y)

Kudos to you !

I
 

AndyW

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Performance curves for the ME1507 sent to me by John at Motenergy.
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AndyW

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Managed to get more of the frame and the seats tacked into place this weekend. Also received the wheels, front hub kits, hydraulic disc brake kit, motor, and more 32650 cells. The Kelly motor controller, DC/DC power supply, and Elcon battery charger are on the way.

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I74

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That's looking fantastic, & also some really nice goodies !!

Are you going to spot weld the batt. tabs,, or do you have some other plan?
 
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AndyW

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That's looking fantastic, & also some really nice goodies !!

Are going to spot weld the batt. tabs,, or do you have some other plan?
Plan on spot welding. Purchased a Malectrics battery spot welder kit. Plan on mounting the battery in a battery box in the floor.
 
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AndyW

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Tack welded more frame in place.
 

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AndyW

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Didn't get much done on the kart this weekend. Just rolled, notched, and tack welded some diagonal supports.
 

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AndyW

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Did more work on the go kart Saturday. We managed to get the a-arm brackets fabricated and welded in place. Also got a good start on the battery box going in the floor.
 

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I74

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Am guessing that you have built race car chassis ect. before ??
Definitely doesn't look like your first rodeo . ;)
 

AndyW

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Worked on the battery box and painted the wheels. My niece has decided on a black and teal paint scheme for the kart.
 

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