Fail Of The Week: An Electric Bicycle, Powered By AA Batteries

Very slowly, some very cool parts are coming out on the market that will make for some awesome builds. Supercapacitors are becoming a thing, and every year, the price of these high power supercaps go a little lower, and the capacity gets a little higher. It’s really only a matter of time before someone hacks some supercaps into an application that’s never been seen before. The Navy is doing it with railguns, and [David] is building an electric bike, powered by AA batteries. While [David]’s bike technically works with the most liberal interpretation of ‘technically’, it’s the journey that counts here.

This project began as an investigation into using supercapacitors in an electric bicycle. Supercaps have an energy density very much above regular capacitors, but far behind lithium cells. Like lithium cells, they need a charge balancer, but if you manage to get everything right you can trickle charge them while still being able to dump all that power in seconds. It’s the perfect application for a rail gun, or for slightly more pedestrian applications, an electric bike with a hill assist button. The idea for this build would be to charge supercaps from a bank of regular ‘ol batteries, and zoom up a hill with about fifteen seconds of assistance.

The design of the pulsed power DC supply is fairly straightforward, with a mouthful of batteries feeding the supercap array through boost regulators, and finally going out to the motor through another set of regulators. Unfortunately, this project never quite worked out. Everything worked; it’s just this isn’t the application for the current generation of supercapacitors. There’s not enough energy density in [David]’s 100F supercaps, and the charging speed from a bunch of AA batteries is slow. For fifteen minutes of charging, [David] gets about fifteen seconds of boost on his bike. That’s great if you only ever have one hill to climb, but really useless in the real world.

That doesn’t mean this project was a complete failure. [David] now has a handy, extremely resilient array of supercaps that will charge off of anything and provide a steady 24V for a surprising amount of time. Right now, he’s using this scrapped project as a backup power supply for his 3D printer. That 100 Watt heated bed slurps down the electrons, but with this repurposed supercap bank, it can survive a 20 second power outage.

It’s a great project, and even if the technology behind supercaps isn’t quite ready to be used as a boost button on an electric bike, it’s still a great example of DIY ingenuity. You can check out [David]’s demo of the supercap bank in action below.

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Hackaday Prize Entry: Smart Electric Bike Controller

One of the more interesting yet underrated technological advances of the last decade or so is big brushless motors and high-capacity batteries. This has brought us everything from quadcopters to good electric cars, usable cordless power tools, and of course electric bicycles. For his Hackaday Prize project, [marcus] is working on a very powerful electric bicycle controller. It can deliver 1000 Watts, it’s got Bluetooth, and there’s even an Android app for some neat diagnostics.

The specs for this eBike controller are pretty much what you would expect. It’s able to deliver a whole Kilowatt, can use 48 V batteries, has regenerative braking, Hall sensors, and has a nifty Android app for settings, displaying speed, voltage and power consumption, diagnostics, and GPS integration.

How is the project progressing? [marcus] has successfully failed a doping test. He lives on the French Riviera, and the Col de la Madonne is a famous road cycling road and favorite test drive of [Lance Armstrong]. The trip from Nice to Italy was beautiful and ended up being a great test of the eBike controller.

London Tries Smart Cities

What’s a smart city? According to Wikipedia, a smart city uses ICT (information and communication technologies) to enhance quality, performance, and interactivity of urban services while reducing costs and resource consumption. Hackers have been using technology to enhance all sorts of things for years.

London is joining forces with cities across Europe to demonstrate smart city technology, mostly in the Royal Borough of Greenwich. The project is in conjunction with the EU Horizon 2020 project, which is still soliciting proposals for funding. It seems like some Hackaday readers–especially in the EU–ought to have some ideas worth funding.

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Extending The Range Of An Electric Bike

Cruising around town on your electric bike is surely a good time…. unless your bike runs out of juice and you end up pedaling a heavy bike, battery, and motor back to your house. This unfortunate event happened to Troy just one too many times. The solution: to extend the range of his electric bike without making permanent modifications.

Troy admits his electric bike is on the lower side of the quality scale. On a good day he could get about 15 miles out of the bike before it required a recharge. He looked into getting more stock battery packs that he could charge and swap out mid-trip but the cost of these was prohibitive. To get the extra mileage, Troy decided on adding a couple of lead-acid batteries to the system.

The Curry-brand bike used a 24vdc battery. Troy happened to have two 12v batteries kicking around, which wired up in series would get him to his 24v goal. The new batteries are mounted on the bike’s cargo rack by way of some hardware store bracketry. The entire new ‘battery pack’ can be removed quickly by way of a few wing nuts.

Connecting the new batteries to the stock system go a little tricky and the stock battery pack did have to be modified slightly. The case was opened and leads were run from the positive and negative terminals to two new banana plugs mounted in the battery pack’s case. The leads from the new batteries plug right into the banana plugs on the stock battery pack. The new and old batteries are wired in parallel to keep the voltage at 24.

Troy found that he’s getting about twice the distance out of his new setup. Not to bad for a couple on-hand batteries and a few dollars in odds and ends.

Self Balancing Vehicle Inspired By Bicycles Of Yesteryear

[XenonJohn] is not a newcomer to the world of self balancing vehicles. He was part of the Medicycle team and a semifinalist for The Hackaday Prize. Working on the Medicycle had exposed some opportunities for improvement of the design, the most significant being the single wide wheel supporting the vehicle and rider. The unicycle design was more difficult to learn to ride than that of a two-wheeled nature. [XenonJohn] wanted to make an improved self balancer and this new one will have two wheels that are independently controlled.

Although the finished product looks like it started with a bike frame, the self-balancer’s frame is actually completely custom. The handlebars and banana seat were purchased new as aftermarket parts for old-style bicycles. Powering the two wheels is a pair of 24v brushed motors, conveniently each one came with a 6:1 reduction gearbox pre-installed. The wheels are a complete compilation of parts not intended to go together. The BMX bike rims were laced to mountain bike front hubs. The hubs have provisions for a disk brake but [XenonJohn] mounted a large toothed pulley there instead. A belt then connects the drive motor gearboxes to the pulleys completing the drive train.

The LiFePO4 battery kit was purchased off eBay and puts out 24v and 15AH using eight cells. These batteries alone were a hefty percentage of the projects cost, costing nearly $300. Controlling the vehicle is an Arduino Mega that makes use of the FreeSix IMU library. The Mega receives inputs via I2C from a Sparkfun SEN-10121 board that contains both accelerometers and gyroscopes along with turn switches connected to the ‘brake’ levers on the handlebars. The Arduino then sends commands to the 25 amp Sabertooth motor controllers to keep you balanced as you buzz around town.

Video below.

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Electric Bicycle Hack is Hilariously Simple

Necessity may be the mother of invention, but limited resources give birth to some of the best hacks. [joejoeboom’s] 5-minute electric bike conversion probably can’t drive you into the next town, but it can scoot you around your neighborhood.

[jojoeboom] found a cordless drill at a local hardware store for $15, which he simply zip-tied to the bicycle’s frame. He positioned the drill so the chuck pressed firmly against the side of the bicycle’s rear wheel, creating a simple friction drive system. To create a throttle, [joejoeboom] strapped a spare hand brake to the handlebar and wrapped the brake’s cable around the drill’s trigger. Several carefully placed zip ties hold everything in place and allow the cable to tug at the trigger when the hand brake is squeezed.

Watch the bike poking around in a video below, and for some extreme contrast check out the 102-mph bicycle build from earlier this summer.

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Electric BMX Has Pedals That Can’t Be Pedalled

electric-bmx

We don’t mind it that there’s no chain connected to these pedals. At least there’s still somewhere to put your feet and our legs are too long to comfortably pedal this size of bike anyway. As you can tell, the added hardware takes care of locomotion using an electric motor.

The first step in this project was to find a steel bike frame to make welding a bit easier than it would be for aluminum. From there the paint was sanded at the attachment points and mounting brackets were fabricated from some angle iron. The rear mount houses a 500W 30A AC motor which uses a chain to drive the rear wheel. A specialty hub was found which allows the added sprocket to be installed on the left side of the rear wheel. Some threading issues prompted [Michael Monaghan] to come up with a method of adding a slot to lock the part in place.

Near the front fork the second mounting bracket holds the batteries; a pair of sealed lead-acid units. The speed control mounts on the top where the rider has easy access to it. The finished bike can get up to thirty miles per hour with a range of up to twenty miles between charges.

If you want your own electric bike on the cheap you can try building one from a salvaged washing machine motor.