The drawing board

Today, we've been playing for about 3 hours with the kart. I've seen the whole neighborhood about 10 times, while driving around for about 10km, on a single charge. The kart is an awesome toy, I've had lots of fun practicing drifting and such :)

Here's something different about the kart. My garage door is covered in blackboard paint, and is the perfect place to do some brainstorming, think out little details, and make miscellaneous notes. Here's a picture of the door:

From top to bottom, you can see a solo brainstorm on how big the threaded wire needed to be to fit the sprocket on the motor, placement of these threads, some small notes on wiring batteries and the length of the chain, some feminine shapes that Els drew because she felt the garage could use a couple of boobs, a sketch of what the battery frame needed to look like, and various drawings by Staf and Louis.

Eureka! It works!

Yesterday, we've had a very successful day getting all the parts together in order to build a first fully running prototype of our electric kart (with the help from Tim and many spectators). We got the whole kart to work quite easily and got a whole bunch of initial test rides out of the kart.

We've had a blast, the kart is lots of fun! As far as building an electric kart goes, I think we have completed this mission quite successfully!

Here's a few pictures of the completed kart contraption:

I don't have any videos of the kart in action here yet, but there were some people that had their cameras so I'm sure we'll have a video up here soon to show the kart's driving capabilities.

I'm very happy with the end result, how well it drives, and that I was actually able to build it myself, with the help of good friends. The idea has been spooking around my head for about a year now, it has taken a lot of brainstorming time, and the actual build has been less than a full-time week.

The kart drives perfectly, just as we hoped for. It has great torque so it speeds up nicely. It's current top speed is about 25kph, as expected. By changing the gear ratios on the transmission we can easily get more speed out of the kart, so that's one of the upcoming todos. We've bumped into some new problems, such as the brakes breaking down on us, and some new creative ideas to pimp the kart, so more action is about to come to the kart.

There's lots of little details that went into finishing the kart, but I'll spend some time explaining these details in later blog posts. For now, it's playtime! W00t!

Hack the planet!!!

Video of motor in action

Here is the stripped assembly in action, showing the motor, controller, batteries and potentiometer all working together without the scooter:

We have all the parts ...

We now have all the parts for finishing the electric kart.

Yesterday, I bought two sets of chains so we can finish the transmission for the kart. I needed to buy two sets as we have a pretty big transmission and we'll need to connect the chains together to bridge the length between the sprockets.

Yesterday evening, together with Walle, we extracted the minimal circuit needed to run the motor from the electric scooter. Below is a low quality picture of the circuit, it shows (from top to bottom) the batteries (still in their boxes but wired up), our main switch, the controller, the throttle, and the motor in its mounting frame. We found some crazy extras in the scooter, like a simple pushbutton that implements a genuine cruise control, but for now we're going minimal.

Tomorrow, Thursday, we'll be finishing the scooter by integrating these electronics on the kart, aligning the sprockets by chaining it up, and hopefully take it out for an initial test drive out on the street.

Rear axle sprocket & initial alignment

I've installed the sprocket on the rear axle, and did some work trying to get it aligned with the sprocket on the motor. Looks good so far, I've installed many bolts on all parts so I can get the remaining wobbles out of the way and the axles and sprockets parallel to each other. Tomorrow, I'll go and get a chain so we can test the alignment and further perfect it.

Tomorrow, I'll join Walle and the remainders of the electric scooter to extract all the cabling and electronics. When that's done we'll have all the parts together for the first time! I guess it'll take another evening's work on getting the electronics installed in preparation for a first test run. We're getting really, really close now.

Sideproject: Motor cover

Dirk brought in the idea to build a protective cover for the engine. The whole motor will be rotating at 450RPM (that's slow for a motor, but fast enough for the putative cutting off of arms and stuff), and is located just right of the driver. Dirk wants to gain some experience points with regards to creating epoxy shapes and building molds to create those shapes, so covering up the dangerous motor is a great test project for learning those techniques.

Here's a picture of the wooden frame that will serve as the base for our protective cover ...

... and here it is, all wired up, ready to become plastered and covered in epoxy, for the final cover:

Do you notice the armrest? It will feature a cup holder, too.

Electric Kart possible future version

This is for version 2 probably (not enough time to get it done for WTH).
But we can use these type of batteries in series (about 32 in series for 48v) they seem to be cheaper and higher AH than lead acid's. But do require a bit of soldering... Also their using a 70000watt motor compared to our humble 500Watts ;)

Please note: This is not our kart!

Batteries mounted

Today, I welded a frame to hold the batteries. Batteries can now easily be mounted onto the kart, and swapped with new packs (we'll get more, new batteries tomorrow) when they run out of juice.

The biggest/loudest/hardest/most daunting parts are now finished. We still need to mount a sprocket on the rear axle (using standard kart parts), align the motor with the rear axle, and get some electronics and cabling on the kart to actually be able to drive it.

The finish is in sight, and I finished all the jobs that I wanted to do this week. Excellent!

Putting things together

I'm putting things together at a steadier pace than I had hoped for. While working on the kart, browsing through the metal parts store and having lots of visits from friends and neighbors (the kart attracts hordes of testosterone driven organisms), we're imagining all sorts of creative ways to build simple and sturdy parts for the kart. I've taken a few days off from work this week, and I feel I'm spending these days well on trying to do something semi useful.

The following picture shows the construction details of how I have mounted the sprocket to the engine. We found a tightening ring that perfectly fits around our engine's drum brake, I've welded some threaded wires to them, perfectly aligned with the existing holes in the sprocket. We're confident it'll be a strong design, the simple construction is a plus.

Here's the kart with it the motor mounted in its frame, and my two little kart-crazy dudes (Clicky-click for more details):

Today, I'll be welding a rack for mounting the batteries to the kart. We'll have the rear axle sprocket on Monday, so we can perfectly align the sprockets by tuning the placement of the motor in the frame.

E-Scooter dissassembly

Here some pictures of the electric scooter dissassembly.
This is the scooter stripped of batteries and engine.


After removing the seat and batteries the controller is now in sight.
This does PWM for the 5 fase 500Watt motor:


Here we have the final part needed for our setup, the
acceleration control and cabling for lights revealed after removing front panels:



Planning on where the motor should go, also we measured the diameter of the
cart wheels and the original scooter wheel. The scooter wheel was 40cm, the karts wheel is
25cm. This turns out to be a good ratio 5/8ts. Or with a 1/1 gear ratio the kart will go 5/8'ts of the scooter maximum speed (roughly 40 km/h so the e-kart will go roughly 25 km/h) but with some extra pulling power (faster accelleration). :


Motor mounted on kart and original scooter batteries for testing in background,
we plan to upgrade these batteries with ones that have a better capacity.




Second gear and chain will be mounted tomorrow together with the batteries.
So stay tuned! Time to get some sleep now ;)

That's all folks!

Construction!

Finally, I've been doing some construction for the electric kart. Here's (part of) my setup out in front of my garage, earlier today. Be reminded that I'm a complete rookie when it comes down to this type of mechanical construction work shizzle.

We have decided not to break the scooter or any of its parts, we just want to use the parts in a non-destructive manner. This requires some extra creativity, but it must be possible not to break the scooter while extracting parts, get a modular system running on the kart and rebuild the scooter with the extracted parts once upon a time.

I've been welding a metal frame to hold our hub motor onto the kart, as in the next picture. This was my first time at trying to weld something useful, it looks more like diarrhea than smooth welding joints. But it sticks. The frame is pretty modular, and is easily and strongly bolted onto the kart's frame. The last job left is that I need to cut grooves in the standing bars so that the motor can rest in them. This needs to be done precisely, such that our motor's axle aligns exactly parallel with the rear axle.

Below is a picture of the motor and a sprocket that we bought from the local karting shop. With Dale's help, we found a ring that tightens perfectly around our motor's built-in drum brake (you can see the ring in the picture, separating the motor and sprocket). I'll weld (6) screw threads onto the ring, which can then be used to fasten the sprocket to the rotating engine with bolts. This seems to be the simplest and strongest solution that we can figure out. (Together with Walle and Dirk I had some discussions about other (flawed?) designs, it's now all upside-down, inside out).

I'm getting more optimistic at getting a running kart by HAR 2009.

Btw, in the process, I've been cutting/drilling/welding/burning my fingers/eyes/balls as well. Nothing lethal, so far.

EXP +10.

We have a scooter, keys, and destruction on our minds

We received the keys to our electric, not street-legal, crap construction, cheap Chinese import scooter.

It looks great in this photo, but it's only worth being destroyed to the bone in order to reuse some essential parts for a new life on our kart's frame. The batteries are pretty much dead, being abused while in stock for too long. We can run for about 500 meters on a night's charge, easily going up to 45 kilometers per hour. But after that, the batteries have already run out of juice.

We'll go and get some new batteries with great amp hours, duct-tape them to the rack at the back of the scooter, and run it again to see whether we get everything good to go out of the scooter and onto the kart. This is quite a remarkable adventure, as the brakes on the scooter are out of order - not that they were any good when we started - but we broke them taking apart the scooter for the first time.

We're trying to get a naked scooter now. We're tearing off cheap plastic panels to access the wiring and electric parts. We're shortcutting useless stuff (like the brakes, heh) and trying to determine the importance of the (few) parts that we need to get a kart running on electricity.

Our first try at really getting an understanding of the scooter's mysterious internals, was to take the back wheel out, which contains the motor, and see how destructive we could get on it. We nearly killed it doing so ... But shortly after forcibly putting the metal parts back together with a hammer, we were riding our brakeless scooter, until the batteries kept dying on us again.

Again, we learned plenty new things. And we're ready for the next step.

We have a scooter (but no keys)

We have picked up our electric scooter yesterday. It's a chinese made "Hao Shun" brand scooter. It sports a set of four 12V batteries under the seat, and a 48V hub motor. The keys to the bike haven't been handed over yet, so we haven't seen it in action yet. Just to make sure everything works, we're not starting to destroy the bike as of yet. Unfortunately, another delay is upon us because of this.

A first problem that needs answering is how we're going to integrate the hub motor, i.e., our motor is embedded in the scooter's rear wheel. This is a common design element in electric scooters (no way this can be done with a gas motor) because it saves energy as there's no friction loss from sprockets or chains in the transmission to the wheel.

In our scooter's motor, the axle is fixed and the wheel with the motor inside rotates. Usually, you would expect a fixed motor with a rotating axle. These are in theory the same things, but there's one difference that needs to be addressed; In the scooter, electricity is being fed to the motor with cables that run through the motor's axle, and not via external connectors to the (rotating) motor block.

As our kart's wheels are smaller than the engine, we'll have to build a transmission from our engine to our rear axle. And since I doubt that we will be able to refit the cables to the engine's block instead of its axle, we'll need to find a way to somehow have a (dangerously) rotating engine with a fixed axle built on top of our kart (e.g., by reusing the fork of the scooter's rear wheel, welded to the kart's engine mount). Additionally, we'll have to fit the rotating engine with a sprocket in order to distribute the rotation to our kart's rear axle and wheels.

So, there's a little bit of progress, and a little bit of extra complexity now. There'll be more to come when we get the keys to our scooter.

Time for some progress

Over the last few months, we've been stuck with budget problems. Getting a motor (like an E-tek R), a controller (like an AllTrax AXE), batteries (4 standard 12V car batteries), battery charger and various parts (cables, components) would've easily set us back 1500 euros, which is quite expensive for building a prototype electric car, just for the fun of building it.

But today, we're at the end of a long quest trying to find a solution for this problem. We've found an importer of Chinese electric scooters in Turnhout. His warehouse/garage is packed with a bunch of electric scooters that aren't allowed on the Belgian market, or on Belgian roads as they're not licensed.

This afternoon, we'll be picking up one of these brand new scooters for about a third of the price we would've paid for separate parts, and we'll have a complete kit to build our kart. The scooter will have a motor, batteries, various electronics and wiring, even stuff like a battery charger will be included. So the plan for the rest of today is to go and pick up this scooter, drive a few rounds with it in order to see how great it is, and then, immediately start tearing apart the shiny, brand new scooter. We'll be extracting the electronics from the scooter, get it back to work outside of the scooter's body, and in the mean time we'll research ways to mount it on our kart.

It's a bit of a shame that we'll be destroying a new scooter, but it'll save us quite a few bucks.

More updates will arrive soon, as time is becoming sparse. We have 1 month left before our showcase at Hacking at Random.