In April, I convinced Fictiv to give me $500 to hack an electric Power Wheels car for the 2016 Maker Faire Bay Area. The faire hosts an annual Power Wheels Racing Series, which challenges makers, builders, and hardware enthusiasts to take those tiny cars for kids, and hack them until grown adults are squeezing in to fly around a track at 20+ MPH.
The result is a mix of great engineering, ingenious hacks, and absurd creativity — all blended in with a little road rage.
While I was able to get Fictiv to fund the car, I still didn’t have a proper build location, so we partnered up with our friends at Mindtribe, who have a small machine shop and a lot of engineering talent.
For those of you crazy enough to enter next year’s race, here are 3 tips we learned from our first year racing to help you get a jump start.
Plan ahead to focus on what’s important
With only 4 weeks (8 build days) till race day, we definitely needed to make the most of our time in the shop.
In order to keep everyone focused on what was most important, we created a basic Product Requirements Doc (PRD), which outlined the following most important features:
Acceleration is more important than top speed
48” turning radius
Batteries must last 40 minutes before replacing
Batteries must take less than 1 minute to change
Car must stop within 18’
Teamwork makes the dream-work
In order to successfully build all the components of the car in such a short build time, we separated into three teams:
Team #1: Drivetrain
Drivetrain team was responsible for selecting the motor, connecting it to the drive axle, and getting the best blend of acceleration and top speed out of our vehicle.
Pro-Tip: Selecting the right components becomes challenging when there are so many options. In order to help single out which motor would work best for our needs, we created this nifty vehicle acceleration and velocity calculator tool to help calculate expected results from the different components we researched online.
Team #2: Braking + Powertrain
Breaking + Powertrain team was responsible for supplying power to the motor, motor controller, throttle, kill switch, and most importantly, stopping the vehicle.
After you have the motor selected, you’ll need something to power the motor and make sure it’s running long enough. Battery capacity becomes a major concern here, so we created another calculator to help pinpoint the exact capacity we needed to keep the motor running for 30 minutes without having to make a pit stop.
Team #3: Steering
Steering team was responsible for designing the car for best possible turning radius, weight distribution, wheels, and driver posture.
We opted to change our wheels for something that would be better suited for a long race on asphalt. The issue then became getting all the components made from the original wheels to fit the new wheels.
We used some makeshift aluminum shims and manually bent steering rods in order to get the new tires to fit.
Have fun, take notes, and repeat
After 4 weeks of dedicating our evenings to building a tiny Power Wheels electric car, we ended up doing pretty well for our first year:
Qualifying Lap: 7th out of 13
45 Lap Race: 5th out of 13
35 Lap Race: 6th out of 13
Endurance Race: 8th out of 13
Moxie: 4th of out 13
Overall: 5th out of 13
While we had some significant snafus during the race (like flat tires and a smoking engine), the best part of the entire race weekend was getting to meet the other teams, checking out the amazing engineering behind these tiny cars, and taking back a tip or two to help improve your car for next year. So do your best and don’t take yourself too seriously!
For more specifics on the challenges we faced in the race and insights, check out our blog post here and see you on the track next year!