|Location||Jamison, Pennsylvania US map|
|Vehicle||1997 Kettler Kettcar |
This kart started out as my friend's Kettcar, but after we had the idea of converting it to an electric go kart, it went from pedal car to fully-functional kart in about a year.
|Motor||Ramsey 21H Winch Motor Permanent Magnet DC|
Most electric motors commonly available for EV's are rated between 3600 and 6000 RPM, with relatively high HP. Normally, winch motors have high torque, but are not capable of high speed. But this motor is rated at 8000 RPM, with 8 HP max. I found it on Ebay for $200. Paired with the 4:1 gear ratio, acceleration and top speed are decent.
|Drivetrain||4:1 Chain Drive.|
Just an average Kelly 24-36 volt controller.
|Batteries||2 Everstart Generic Marine, 12.00 Volt, Lead-Acid, AGM|
When it came to buying the batteries, I considered Optima Yellow Tops, Sealed Lead-Acid, and even cheap lithium batteries. I singled them out one by one; Optimas were way overpriced, sealed lead-acids are usually too low amperage, and I had no way to charge lithium. So I high tailed it over to Walmart where I heard they were selling generic marine batteries on the cheap. And so they were. At 69 bucks a pop these were the best option I had. Very heavy duty, as well. They hold up well, although heavy, and produce what I need.
Had to change batteries due to size restrictions. I really didn't realize how little space I had to work with...Instead, I bought two of their smaller marines, which are rated at 70ah/hours each.
|System Voltage||24 Volts|
|Charger|| Diehard Platinum Battery Charger|
Bought this Diehard Platinum Battery charger from Sears a couple of years back for my dad's car. It was less than a hundred bucks—I think $69.99, or something like that. It will do AGM/Gel Cells, Marine Deep Cycles, Regular lead-acid, and it has a special setting for their Diehard Platinum Battery. What's great is that it has a 40 amp rate setting, which speeds up charging massively.
|Heater||The sun. Otherwise, put your hand on the motor after running.|
|Instrumentation||Rigged an aging Cat Eye bicycle speedo to it. Had it running for about 5 minutes before it totally died on me. Indicated somewhere around 25 mph.|
|Top Speed||30 MPH (48 KPH)|
Decent. 30 mph feels like a hell of a lot faster when you're sitting 3 1/2 inches off the ground.
I needed to downgrade on batteries due to size restrictions. Top speed (revised) is about 30 mph from my previous (generous) estimate of 63...as if I would have EVER ridden the thing at 63mph.
|Acceleration||Decent. Like top speed I over estimated the capabilities of the kart not taking into consideration the extra weight of the batteries. It will get from 0 to top speed in 7.5 seconds. This also has to do with the fact that I downgraded on battery power.|
|Range||10 Miles (16 Kilometers)|
Unknown, as of now. I'm prepared for the worst, but I'm expecting somewhere between 10 and 20 miles. With generous, half-or-less accelerator driving, it should be higher, maybe 25-30, but no higher, mostly because I'm only using 2 batteries when I could have used at least 4.
Revision. I'm expecting a range of maybe 10 miles. I did drive it hard for 3 days on end without recharge, and had only depleted the batteries to about 20% DOD, so that was some good news.
|Seating Capacity||1 Regular-Sized Adult|
I'm 5' 10", which is a somewhat average height, and I don't have too much of an issue getting in, riding, or getting out of it. Even though my friend complains about his knees hitting the wheel, it isn't that much of an issue. That's what go karts are about.
|Curb Weight||150 Pounds (68 Kilograms)|
Not too heavy, but again it isn't built like a steamboat. I can, with the help of two people, or even just barely by myself, haul it into the back of my VW Passat.
|Tires||Azusa Engineering 410/350x5 Studded Tires on the rear|
Some Harbor Freight generic hand truck wheels on the front
|Conversion Time||Longer than I'd have liked. The entire process, from pedal car to electric go kart (and one small conversion in between using a Razor electric scooter system) took about a year, with intermittent periods of rest. If I had been diligent about it, I could have hammered the entire thing out in 3-5 months. I'll keep that in mind for next time.|
|Conversion Cost||As of now, $753.78. Electrical (not including motor): $415.00, Chassis upgrades: $120.78, and Motor: $218.00|
|Additional Features||A rear axle that's about 1 foot longer on each side of the kart than the steering linkage (although performance is not affected).|
Genuine Kettler Kettcar Plastic Seat
No brakes (as of now, YEAH!)
Lots of other things that are special.
|Well, it was a lot of fun building this thing. If I had had the option at the time, I would have welded the axle mounts to the frame, let alone everything, but I didn't, and the bolts are quite sturdy. The 5/16" steel bolts I used are really doing the job. |
Instead of 1/2" aluminum plating, I decided to use some angle steel from Sears Hardware for the motor mount. This worked out quite well, and I will post some pictures. I have also considered mounting two pieces of steel angle on either side of the wheel (near the floor) to reinforce the frame in the case that I can't afford an entire new floor. I'm still trying to decide.
The rear wheels are smaller than I had planned, although it sounds unreasonable. I was actually hoping to purchase 2 live axle hubs with a step in them, and some almost trailer-sized wheels (about 18.5 inches in diameter), which would have given better overall power transfer to the pavement and increased top speed. The steering linkage is unacceptable, and the only proper work that has really been done so far is the mounting of the rear axle, and I honestly didn't put that much forethought into it. If I ever want to achieve higher speeds, I will definitely build my frame, use a proper steering linkage, and other non duct-tape-and-glue-type building methods.
The brake situation; I'm not really sure where to go with it. It definitely NEEDS brakes, but I can't find an efficient way of mounting the caliper onto the frame. The motor has very high resistance, which helps the situation. But I will definitely have brakes on it eventually. Bad things without them.
I'm glad I didn't settle for a Scott 1HP Permanent Magnet Motor, since that's what I was looking at. 1 HP is obviously more than enough for good top speed, as long as you use a corresponding gear ratio, but I found this great 8HP 8000 RPM motor on Ebay for $200 as opposed to $500, so I'm happy that I saved a nice chunk of money.
*Update, July 3, 2009*
I have finally managed to mount all of the electronics and the motor, and I have done some speed and acceleration tests. Because I had to downgrade my batteries from the Everstart MAXX to Walmart's generic marine (due to size restrictions), the amperage is less, thus acceleration is reduced, as well as top speed. Top speed at this point is somewhere around 30 MPH and acceleration from 0-Top Speed is around 7.7 seconds.
*Update, July 17, 2009*
After returning from vacation, I took the kart on a couple of speed runs. The motor gets really warm really fast, but the normal operating temperature is 150 degrees C+, which is odd for such as tiny motor. The throttle is finicky, with the wires coming undone every few feet. I constantly need to stop, reattach the wires, and cycle the power. It's a real pain; I'll need figure out a permanent solution soon. I've reconfigured the controller for torque and not speed, improving the acceleration from 0 to top speed to about 5.9 seconds. With these settings, top speed is reduced to about 23 MPH.
*Update, August 7, 2009*
I was driving the kart the other day, when I heard a funny noise coming from the front-right wheel (oriented in the driver's seat). I took a couple spins around my neighborhood, and everything was working well; the throttle wires were holding, but then the worst. I heard a slight wah-wah-wah sound from the wheel, so I stopped and took a look. Everything seemed in order, so I continued. I began driving slightly uphill, and the wheel started complaining again, but this time I completely disregarded it. My foot was only halfway down, so I floored the accelerator. Suddenly, the wheel launched off to the right. My right side crashed to the ground and the kart skidded for a good 100 yards before coming to an abrupt halt. I was completely confused as to what had happened, so I climbed out to check out the damage. The electronics had survived; the wheel, not so much. It turns out that at some point, the hub of the wheel had somehow separated from the rim, not by the bolts, and because my fudged system was only holding the hub on, the rim and tire shot off in another direction. Afterward, I realized that the hub was still on the spindle. After all of this, I have realized that the duct-tape-and-glue approach that I used to modify the kart was unacceptable, and that I should have built or bought a use-specific frame. I will be soon starting construction on a use-built frame. Details soon.
*Update, August 14, 2009*
I ran out to Tractor Supply yesterday and bought some new wheels. I just couldn't stand to let it sit in the garage with no use...it was a heart breaker. I fixed the wheels so this time they will last a while longer before giving out...or total other failure.
*Update, September 7, 2009*
I took some time during my last real weekend of vacation and fixed all of the faulty wiring on the kart. I reduced the number of overall wires for complexity's sake, and bought some new lugs that will be able to take the heat from the high current being sent thorough the controller. When I drive the kart hard for even a few minutes (the least I have driven it for hard is about 15 minutes), the motor gives out as well. I could call it saturation, or maybe even a duty cycle. Whichever it is, the motor is terrible about it. About 2 days ago I took it for a speed run in the parking lot of the elementary school right across the street from my neighborhood. The ride only took about 10 minutes. When I returned home, and attempted to ride up my driveway, the kart just wouldn't do it. The motor was hot as hell, hotter than normal. I don't mean that it was casing-melt hot, but warmer than it is on average. I don't know why the motor performs this way, but I can only ride the kart for so long before it needs to cool down. It could have something to do with the fact that the motor has really no cooling mechanism whatsoever; no fans, no vents, just the case.