Hacky Racers is a new racing league created by a few bored engineers who like the idea of soap box racing, but want more power. The concept is based heavily on the US Powerwheels Racing Series, which takes toy electric cars and crank them up to 11 to compete against each other in races. The rules allow a budget of £500 to build an electric race car to race others around a circuit. Style is as important as speed, ensuring a suitable level of crazy. Each car is fitted with a fuse to keep a level playing field, and there are some safety rules too (see www.hackyracers.co.uk for the full list) but other than that it's pretty open.
This is the story behind my racer, the Dustbin 7. It was built in around 4 days costing about £400, and is both great fun and terrifying, as all good projects should be!
I had been invited to participate at Fully Charged Live at Silverstone, the largest electic vehicle show in the UK to date, with my Hacky Racer to help us spread the word about what we were doing. This was great, except I only had two weekends free before Fully Charged Live, and I hadn't started building yet.. Better get on with it!
As with any good project, I started with some research. This was mainly looking at how things were being done in the US; my racer was one of the first built in the UK so it's still a bit of a blank sheet over here. I found that one of the most common drive systems appeared to be the budget scooter motors available on eBay, either a pair of 1kw brushed ones, or a 2kw brushless one. A lot of people also use water cooled hobby brushless motors and the like, but those require a bit more work to get right, and given I only had a few days to build it, I decided to keep things simple and get myself a 2kw brushless scooter motor.
They're much bigger than a standard hobby brushless motor for its power, but have a lot of thermal mass and are designed for continuous running without additional cooling. At £80 it's not the cheapest solution out there, but it definitely seems to be one of the more reliable.
To control it, I bought a 1.5kW 48v brushless ebike ESC for £30, which while its a little underrated for the motor, it was a lot cheaper than the 2kw version, and I was reliably informed by the PRS lot that it'd work just fine. The instructions were entirely in Chinese, but with the help of a good camera translator app I got it all wired up and working.
The batteries commonly used in the US were Nissan Leaf cells stripped out of scrap cars and sold on cheap. Unfortunately this doesn't appear to be a thing in the UK, so I went for the slighly more volatile lipo packs. Batteries are usually the most expensive part, and as such we allow them to only count %50 towards the total budget. I bought 6 x 16Ah 4S Multistar packs for £260 (they were on offer), which makes 2 full sets so I can charge one set while racing with the other... That was the plan at least, but one of the packs was dodgy on arrival and they had been discontinued and I apparently got the last ones, but anyway, I had batteries.
Now I had most of the electronics covered, I started on the hardware. I decided to go for a classic car theme, as I have a set of shelves filled with old Triumph parts, including an old Herald seat which I wanted to use as it was particularly comfortable! For the wheels and steering I used parts 'borrowed' from an old Formula 24 kit my school was getting rid of many years ago. It just consisted of some electric wheelchair wheels and some really flimsy steering axels, but it had some nicely made hubs to attach everything. Also had a hub for a bike brake disc which saved a lot of work on the brakes. I got a length of 20mm diameter silver steel for the back axel and some bearings to match. I laid all out these parts along with the steering wheel was from an old...Read more »