[Will] is on the electric vehicle team at Duke, and this year they’re trying to finally beat a high school team. This year they’re going all out with a monocoque carbon fiber body, and since [Will] is on the electronics team, he’s trying his best by building a new brushless DC motor controller.
Last year, a rule change required the Duke team to build a custom controller, and this time around they’re refining their earlier controller by making it smaller and putting a more beginner-friendly microcontroller on board. Last years used an STM32, but this time around they’re using a Teensy 3.1. The driver itself is a TI DRV8301, a somewhat magical 3 phase 2A gate driver.
The most efficient strategy of driving a motor is to pulse the throttle a little bit and coast the rest of the time. It’s the strategy most of the other teams in the competition use, but this driver is over-engineered by a large margin. [Will] put up a video of the motor controller in action, you can check that out below.
Continue reading “BLDC Controller With The Teensy 3.1″
Raise your hand if you have designed and built a full size car…. Nobody? Doing so would be a huge task considering car manufactures have thousands of people involved with designing and building a car model. Eager beaver [Neil] has stepped up and taken on that challenge. He’s started an open source project he’s calling the CarBEN.
The plan is for the car to hold 5 people comfortably while being just a tad larger than a Scion xA. The body is made of foam and will be covered with fiberglass. The car is designed in a shape that tapers in towards the rear of the car and has features like a smooth underside and covered wheels to create a low coefficient of drag. The goal is for this beauty to get 300-400 miles per charge with an Miles Per Gallon Equivalent of over 224.
Continue reading “Open Source Electric Car, CarBEN, Produces No Carbon”
If you’re building an electric car nowadays, you’re probably looking at taking a normal, gas-powered car and replacing the engine and transmission with an electric motor and batteries. [Gahaar] thought this is a rather dumb idea; all the excesses of an internal combustion-powered car, such as exhaust, cooling, differential, and fuel storage is completely unnecessary. Building a new electric car from the frame up is a vastly more efficient means of having your own electric car. So that’s what he did.
[Gahaar] build his new chassis around a single box made of 3mm aluminum sheet. Attached to this box are two AC induction motors at the rear of the car, negating the need for a differential, with 45 lithium cells stuffed into the middle of the box. There’s no gearbox here, greatly reducing the complexity of the build, and with the batteries providing 145V and 100Ah, this simple car has more than enough power for a lot of fun.
The suspension and steering were taken from a wrecked car, in this case a Mazda MX5, or Miata for those of us in North America. The Miata suspension easily unbolts from the frame of the wrecked car, and with just a little bit of welding can easily be attached to the new electric chassis.
Even though [Gahaar]’s car is basically just a bit of aluminum, motors, suspension, and batteries, he’s getting some awesome performance out of it; he estimates a top speed of 100mph with about 60 miles per charge. It’s an awesome way to get around the farm, and with a custom fiberglass body, we can easily see this being one of the coolest electric vehicles ever made.
[Kurt] wanted an electric car, and always wanted to drive a Porsche. Killing two birds with one stone, he decided to combine these wishes and convert a 2002 Porsche 911 into an electric vehicle.
After removing the engine, fuel tank, exhaust, radiator, and all the other things that make an internal combustion engine work, [Kurt] installed a high power motor, controller and 72 lithium phosphate batteries weighing in at over 500 pounds. He’s put over 300 miles on the car in the last few months while working out the kinks, but now he’s finally gotten the bugs out of the system allowing him to take it up to some relatively high speeds.
Already [Kurt] has taken his new ride to 100 mph and done a little bit of range testing that told him he should expect around 40 miles per charge in his new ride. It’s not exactly what he hoped, but more than enough for a few trips around town while riding in style.
After the break is a video [Kurt]’s first test drive of his electric Porsche.
Continue reading “Porsche 911 made electric”
[Juan] dropped us a note to let us know about a little project he’s working on. A few years ago, he bought a Honda S2000. It served him well, but now he’s converting it to electric power, and it’s going to be a beast.
[Juan] is using 104 battery packs each containing 4 cells in parallel. The total output of his battery assemblage is 686 kilowatts, or 920 horsepower. [Juan] is assuming his drive train will be 85% efficient, meaning his wheels will be getting 782 horsepower and 1500 ft/lbs of torque at 0 rpm. Yes, this thing is going to scream.
A project of this caliber is usually undertaken by gear heads with decades of experience, but that’s not the case for [Juan]; he’s still a senior in High School. A build this awesome can only portend a very bright future as an engineer and certainly a few drag race wins. This car is going to be a monster, and we can’t wait to see it on the track.
[Mikey] got a real deal on some A123 Pouch Cells. These are large Lithium cells that tolerate 100A discharge and 50A recharge currents, with 20 AH of life off of one charge. He’s been doing a bunch of testing to find out if the cells can go into an expandable battery pack and be made for use with hybrid cars.
We just looked in on a battery tester used for solar power car arrays. This is a similar situation except [Mikey] is focusing on the test data, rather than the apparatus. The link above is a collection of his notes from testing. Start reading at the bottom of the page up to get the chronology right. He starts to zero in on the most efficient charging methods. Immediately he’s hit with a big need for cooling as the cells take no time to pass 100 degree Fahrenheit. He continues testing with heat sink and fan, and even brings a thermal imaging camera to help with the design.
We do see hacking in mainstream print media from time to time, but you know the movement must be gathering steam when a collection of hacks gets the cover story in a local paper. This week’s issue of The Isthmus – the premiere free newspaper here in Madison, WI – features the local hackerspace and a handful of green hacks.
The man seen riding the pedal-powered plow above is [Kevin Blake], a mechanical engineer for Trek Bicycles which is headquartered in Waterloo, WI. He built the rig with the chassis of a riding lawnmower, adding shovel blades in a V-shape on the front, with cranks and other parts salvaged from bicycles.
The article goes on to feature the local hackerspace, Sector67, by interviewing its founder, [Chris Meyer]. The paper tracked down some other local hackers (and Sector67 members) who have been prototyping wind turbines.
The largest feature in the story goes to [Ben Nelson’s] Geo Metro electric vehicle conversion. The self-employed video producer picked up the diminutive car for about $500 and dropped in a forklift motor which he picked up at a garage sale ($50 + $50 for new brushes makes for a steal at $100). But here’s the best part of the project: after ripping out the unneeded parts for the car he sold them for $550. Anyway, all said and done he’s got about $1300 invested in the project and now has an all-electric car that gets up to 45 mph with a range of twenty miles in between charges. Maybe a big tail cone would help extend that reach.
This is the most interesting stuff we’ve read in the newspaper in years. Maybe you should contact your local journalists for a feature in your area? If they’re not receptive, don’t fret… we’re always looking for great builds to feature here at Hackaday.