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Christian's Go Kart
He has upgraded his Mattel "Power Wheels" for a 48V High Power Electric Go Cart. Yahoo! Christian was barely four when we bought him a Mattel Power Wheels truck. That little motorized truck had trouble climbing a slight grade. And each time he drove it into the park basin near our home, it had to be pushed to get out. He's seven now, and so we spent some time assembling the E-Cart he really wanted.
The Cart project gave me an opportunity to use some of the tools at my disposal. Lathe, CNC, jig bender, and a nifty wire feed welder. The experience will be handy for assembling an electric K-1 Attack roadster that has been sitting as a huge pile of parts, taking up precious space in my company's prototyping shop.
This thing is fast. Really fast. I had the foresight to use a programmable controller, and have set some very conservative limits on both the acceleration and the top speed. Otherwise it would lift the front wheels on full power acceleration when punched. He has a helmet, and always wears it.
The controls are arranged as usual. Accelerator on the right, Brake on the left. Note the cables. There are dual disc brakes, with individual cables for each caliper. The accelerator cable connects to a remote mounted control pot in the drive section.
A single three-position key switch is arranged as Reverse, Off, Forward The key does remove in the center Off position. Steering axles are fully ball bearing supported, and swivel bearings for coupling to the wheel. Very smooth, with no slop.
Top view of the 48V electric drive. Showing the AllTrax AXE Controller, main Contactor, and reversing Contactor. The four 12V 18aH Panasonic VRLA batteries can deliver nearly 200 amps to the motor on full power acceleration. The power electronics section is enclosed by a thermally formed clear Lexan cover. A 250A fuse protects the system.
Underside view from the rear. Note the dual disc brakes, and the full differential drive system. This is the real deal. The drive system came from a scooter that had been designed to transport the equivalent of "Jabba The Hut" around Mal Wart. It has a large PM motor, originally running 24v, with a top speed of around 7mph. The motor armature was rewound with larger gauge wire and fewer turns to deliver considerably more power. Yes, the motor does get very hot. A "hitch" was included so that he could pull his two sisters around in a wagon. Charger plug is to the right of the hitch.
An intelligent 5 amp 48VDC charger keeps the batteries ready to go. This model is amazing, and it will not overcharge the series string VRLA batteries. Surprisingly, the batteries stay in perfect balance. This is the second charger I used. The first charger bought off ebay severely overcharged the VRLA batteries, and the batteries had to be relaced after a few months. Beware of cheaply designed chargers.
Note the gray rubber rear tires. No more skid marks and "burn out" patches on the driveway. They actually tend to "erase" any other marks off the driveway surface too!
Side view showing the accelerator pot box mounted below the AllTrax AXE controller.
The disc brake rotors and calipers were originally used on Pocket Bikes. They were an easy adaption to use them in a Go Cart application, and include precision adjustments to maintain good braking pressure balance.
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