Thread: Electrathon - A Different Kind of "Hotrod"

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That's fairly similar to what I do except for squeezing the parallel pairs. I tighten the nipples until the threads are just covered; that gets them all the same. Then I start going around and around the wheel tightening the spokes with my fingers a couple of turns at a time until there is no slop left. Then I use the screw driver to finish getting the spokes tight and the wheel true. I've done enough of them now that I can drill the rim, drill the hub, and lace the wheel complete in about an hour.

Sorry for the steering bearing tangent. I was looking back over my notes and saw that it was thebat that references steering bearing in post #49. I didn't notice that the post was not written by you and kept looking for other references...

Started welding up some prototypes of steering knuckles, kingpin bosses, and spindles out of scrape. For anyone new to this type of vehicle design, there is nothing like a working prototype to help understand how thing are going to fit together.

Do you have any experience with hydraulic brakes on these vehicles? I found a set of free levers and calipers from a junked bike. I don't want to add too much complexity to save a couple of bucks at this stage. The Bengal brakes you mentioned seem to be about $65 for a pair.

No apology necessary. The Bat and his son won the national competition for human powered vehicles some years ago. I consider him something of a mechanical genius. A few years ago he took a bunch of leftover bicycle parts, a rejected controller from a golf cart, and a worn out Scott 1hp motor and proceeded to stomp the competition in Electrathon for the next two years! Then he went quietly back to building hotrods at his home in Miami.

I use 1/2 inch o.d. tubing from ACE Hardware to make my kingpin bosses. It has a 3/8 inch i.d. which is perfect for a 3/8" grade 5 bolt that I use for the kingpin. For my steering knuckles I use 1/4" x 1 1/4" flat stock. I tried 3/16" x 1 1/4", but had trouble with it bending under stress on the tight courses. For the spindle shafts I use either 1/2" or 9/16" (depending on which hubs I'm using) grade 8 bolts, 5 inches long. My cars have hit concrete curbs, parking bumpers, and other cars. I have had the front axles bent numerous times and broke or bent rims several times and I am yet to ever break a spindle.

I haven't tried the hydraulic brakes because they usually come as a sealed unit (can't bleed them) and the hydraulic lines are either too long or too short. So far, the ones I've seen were too pricey for me to experiment with cutting and splicing lines, trying to bleed them, etc. If you can get some freebies and make them work they should be great.

Another update for the week....

Spent the early part of the week assembling and disassembling wheels until I was satisfied with 3 fronts and a rear.

For welding practice I tried to run clean beads around a piece of .060 steel tube.

Was a bit overwhelmed by the steering. In the past, I have work on enough bikes and robots that the drive train; controller, motor, and chain/gearing makes sense. After a couple of front end prototypes, I feel much better. I picked up the disks and calipers so I could start thinking how to mount the calipers.

Felt confident enough to order the tube and bar to start working full sized steering mock ups.

Finally, started looking for motors, controllers, and batteries. They won't be needed for quite a while, but I would like to put them on the plywood mock-up I am using the fit the car around the driver. Hopefully I can borrow the bathroom scale and make sure the my math matches reality for the weight distribution calculations

Finally, Russ Buddin from Iowa was kind enough to send me a set of OPPD's Powerdrive instructors workshop DVDs. I watched the first over lunch good stuff.

I build my frames from 1/2" and 3/4" EMT conduit. Instead of continuous bead welds, I use a series of overlapping tack welds to avoid blowing holes in the conduit tubing.

I have attached a couple of pix of front spindles on a bare chassis so you can see the caliper brackets. Notice that the right and left sides are different because of the shape of the calipers. I make a cardboard pattern for each side and then cut them from 16 gauge steel. I fit and install them with the wheel, disc, and caliper all assembled. I tack them in place, then remove the wheel and caliper so I can finish welding.

There are many controllers to choose from and the sky is the limit on prices. My advice is to go as cheaply as possible. I have seen all kinds of controllers from used golf cart units to high tech programmable ones. There is no real advantage on the track. Alltrax and Curtis are my preferred brands because of their simplicity of wiring and reliability.

I have to chime in that this is a fascinating thread. Makes me want to try an electric car build down the line after a few other projects get done!

Go for it, Steve. Playing with these things has been quite an education. For a long time I've been toying with the idea of building a street legal version. I would make it larger so it could be seen in traffic and also so I could haul a small "payload" like a weeks worth of groceries or maybe a passenger. Maybe some day...

Jim I might just do that. Today I'm cleaning house on a bunch of vintage stereo stuff. I have been delving in electronic stereophnic stuff from the 60's and 70's during the winter, when I couldn't work on my truck project. I actually learned enough on my own and thru forums for stereo equipment that I volunteer at the local hospice thrift store and fix up stereo stuff for them. It's amazing what people throw away when their parents pass on, that they have no concept of quality or value. To date my old Marantz reciever coupled with Epicure Speakers and a magnetic drive JVC turntable delivers a sound that nothing new on the market comes close to unless your paying tens of thousands of dollars, where as I got about 400 into that system. Anyway I digress, but once the extra stuff is cleared out and the truck is road worthy, then something like an electric car/bike project would be a lot of fun to do, plus out local ace hardware is 2 blocks from my house!

Excellent advice on the overlapping welds.

I spend a few hours practicing this weekend. I found that putting eight tacks around a joint and then running a bead from one tack to the next really helped me direct my focus. It still looks a lot like dog poop. But at least the dog is no longer sick

I ordered a cheap gokart master brake cylinder for $29 on ebay, It looks like it will work well enough as a proof of concept.

I bit the bullet and ordered a Motenergy ME0909 motor and Alltrax AXE4834 PM Controller. $720 total. Sadly, with the wheels and frame materials, this pushes me ahead for my initial original budget of $1000 per year for two years for the project. I guess I need to revisit the budget

@stovens,

I highly recommend the project. Personally, I have never had the time, space, or tools to work on a full sized hot rod. The electrathon vehicle seems to be a good first step. For $1500 and 6 months of evenings it feel like a relatively inexperienced person can put together a vehicle that can a least complete a couple of races. Then if one takes a second season to revise their plans they can have a reasonably competitive vehicle.

The breadth of topics covered is amazing!

That's a good price for the motor and controller. Did you get a special price for buying them together? The Motenergy ME0909 looks like an updated version of the Briggs Etek. I've not seen one in person, yet, and I am interested to see how it performs. If it's as good as my old Eteks you'll be very happy. The good news is, if you like this motor you can use it almost forever. When I sell a car and build a new one, I just move the motor and controller to the new car. I've built 10 cars, but I've been using the same 3 Etek motors since 2004 and they seem to keep getting better with age!

It costs me just under $1,000 in parts and components to build a new car using all new materials. (That does not include the motor and controller.) Having done this enough times, I know what I need and have very little wasted material. It was a different story when I started out, though. I cut that first car up and started over twice! It finally ended up as the orange and silver car seen below.

Excellent inspiration!

Initially I was looking at the Etek motor. They seem to be the most well understood motor in the sport. However, the market for used Eteks is pretty tight. I take to be a good sign that the motors are high quality and the sport is growing at a steady pace. The ME0909 seems to be the succor to the Etek.

I used the same criteria for the controller. It appears to be very common and well understood. I went with a match set.

I am going to head off a bit into the world of experimentation with the batteries. My intention is to make a 1 KW/H LiPo batttery out of recycled laptop cells (18650) which is the same type the Telsa model S uses. I have worked with these a bit on robots. It should be possible the keep the weight under the 14 lbs as specified in the handbook.

The 1KW/H target keeps me in the same energy ballpark as stock electrathon racers. The upside is they are cheap, about $50 for a 1KW/H module. The downside is they tend to perform poorly when drained at greater than 1C such as when accelerating.

It will be interesting to see if the reduced capacity is worth the reduction of 50 lbs of weight.

Just a quick word of advice... Build your battery trays so that they can accommodate full size automotive batteries. The reason being that you may want to change to conventional batteries later. Here in Florida there are only two cars running in the Experimental battery class. If one of them doesn't show up, the other one is basically making practice laps because there's no class for him to run in. It's not much fun when there is nobody to compete against. Are there other cars running in the Experimental battery class in your area?

Agreed,

I am trying to be flexible with the batteries so that if they don't work I can fallback to standand SLA batteries.

On the other hand from my limited research it seems that most of the students and teachers involved in electrathon are gearheads No one has really looked into alternative batteries past the price and potential danger. A safe, DIY, battery for under $100 might provide interesting options.

If the experimental class becomes boring, I was thinking about implementing some sort of handicap like golfers use. My first thoughts were to self limit the available energy the vehicle uses until it performs on par with other cars.

There may be teams in your area that run in the Experimental class all the time so you'll have somebody to compete against. You'll need to go to an event to find out...

Actually, the kids involved seem to be a pretty equal mix of gearheads and nerds! When I was teaching and mentoring a team I was always amused by such diverse kids working together so well. Ordinarily the grease monkeys and eggheads avoid each other like they have contagious diseases, but Electrathon seems to bring them together and they end up making new friends.

Yes, price can be a critical factor to some teams, especially the high schools. Most of them don't have expendable funds to experiment with, so they stick with the "tried and true". I run Optima Yellow Top batteries. I bought 4 of them in April of 2010 and 4 more in December of 2010. I'm still using them!

There have been attempts to equalize the different battery types before. Usually, ballast is added to make up the difference in weight. For instance, Standard Battery class is limited to 73 pounds of batteries while Lithium is limited to 22 pounds. Simply add 51 pounds of ballast and the cars should be equal, right? It doesn't quite work that way because Lithium batteries perform differently; they still have a performance advantage. If you can find a viable way to equalize the Experimentals with the Standards I'm certain that Electrathon America would be very grateful.

It is great to hear the this project is a place where gearheads and nerds come together to solve problems. I have a foot in each group

I spent most of the last two weeks on batteries. The two systems I am testing are building pack out of 18650 cells and pre-built Nissan Leaf modules. I like the Nissan Leaf route because they are about the same capacity and cost as the red and yellow top battery. The DIY pack is a great learning experience.

I ordered 20 100W power resistors to build a resistive load bank to test various batteries against the workloads they will experience in a actual race. They should arrive in a couple of weeks

The motor and controller arrive in good condition. I borrowed a couple of 12V batteries from the garden tractor and a car to test the motor. It spun up right away. Over the long weekend I hope to spec

For the most part the subsystems are coming together nicely

My current hiccup is gearing. If I run the motor at 48 volts, it will spin twice as fast as at 24 volts. This would require a driven sprocket of about 120 teeth instead of the standard 60 teeth used by shiftev in their rear hub adapter. It looks like I might have to have shiftev fabricate something so I can use standard 6 hole gokart sprockets with their adaptor.

I just fired up the garage furnace. Hope everyone has a enjoyable and productive thanksgiving weekend.