I have heard that there is a car in Florida that is running 48 volts and an AC system that is winning all of his races by 4 to 10 laps. I know that most street cars are now AC because they are far more effecient. Does AC make that much difference in other electrathon cars out there?
There have been several requests for a rule change request to put the AC cars into the 'experimental class'. One of the goals of Electrathon is to have an affordable race that all can get into for about $1000. I looked at AC a couple of years ago and to get into it then was well over $1000 just for the motor and controller. Since this is above most of the school's budgets and not really in the spirit of making a better car using standard supplies what do others think about this?
I realize that the experimental class has several sub-sections with each type of battery a possible new class as well as solar and non solar with lead acid and each type of battery. If we do add AC to the experimental class how can we group them all into one or two classes and not have cars racing against themselves because they are the only car at that race with XYZ batteries, an AC system and Solar Panels????
I am looking for input from members as well as any input about cars in other areas. I don't think there are any AC cars in the NW but I may be wrong.
I think there were one or two cars that have shown up at PIR that were AC in the last couple years. I don't think they won, but that was likely for other reasons.
If the motor and controller can be bought for $1000, sounds like less than many are currently paying for an etek and a controller. A few years ago when we were running Scotts motors and eteks came along, everyone quickly changed mtors and we all went faster/farther. Remember the old days when few people finished a race?
As I have expressed before, I am really against splitting the classes. There were probibly too many when there were 4, there are WAY to many now. Even more is just more bad.
Possibly someone who knows te specs on the AC and DC systems can speek up.
The least expensive AC motor/controller combination I have found online is $2125 (Thunderstruck Motors). A brand new Etek is $499 (Robot Marketplace) and Alltrax controllers start at $250 (Ebay).
If (and I emphasize IF because we're trying to determine if) the AC systems have a distinct advantage over DC systems, then they should be relegated to the Experimental class to keep this sport from becoming a money contest. If the Standard class is limited to DC systems only, then all those cars are on a pretty "level playing field" from a power standpoint and the emphasis goes back to the design, construction, and fine-tuning of the chassis/body. That is, after all, where the real educational value lies in these cars. Simply buying and bolting in the latest high-zoot super-dooper power train or switching to expensive lightweight batteries and chargers does not advance technology or enhance learning; it just shows who is able and willing to spend.
I, too, would like someone who can explain the specs and differences with facts and figures.
Jim, Is this the #39 car that ran away from everybody at our race last year? I KNEW something was funny. He told me he was running 48v but said nothing about AC powre. Hmmm.....
We posted details about the #39 ProEV Super Coupe in the show off section back in July. The link is here: http://electrathonamerica.activeboard.com/t49915229/proev-super-coupe/
We also have big plans to write up about our adventures on the ProEV website. The Tampa Bay Electrathon series is a very fun series with a great group of people. They welcome newcomers and everyone helped get us out there with advice and assistance.
I suspect our AC motor is not very expensive. It was thrown in for free when we brought the used chassis from Mike at Blue Sky Design. He did not have the controller for it but assured us we could pull the motor and fit an Etek.
The controller belonged to Sykromotive. They build a well respected DC controller and were exploring the possibility of selling a small AC controller. The project had fallen off the radar screen but Ives still had the orginal controller and offered to sell it to me for $349. He was able to tell me that the motor was a permanent magnet AC motor. It does not have any label so that is all I know.
The controller is nice and light. It's limits can be set using Sykromotive's software and a USB connection and you can record data (if you don't mind carrying a laptop in your lap).
The other thing I really like is that Ives has published his communication protocol to allow anyone to write their own software to read the data. This summer we built a Watt hour meter using a open source $25 Arduino computer.
If this motor had not been an option, we had planned to look at running r/c electric motors. They are permanent magnet brushless DC motors (Search the internet for 'go carts running rc electric motors'). Another Florida team, the Electrocutioners, are already running one. I think, motor and controller together cost less than $500.
So cost wise, you can find options cheaper than the Etecs, both AC and brushless DC. It takes some willingness to experiment and it is hard to guess what will be best.
AC advantages: Regenerative braking for passing other vehicles cleanly. It makes it easy for the other vehicle to see you if you get all the way along side them under Regen brakes.
The Etec is suppose to be 90% efficient so I have a hard time believing the AC motor has much of an advantage there.
Last season, we had the smallest frontal area and the sleekest vehicle. We rebuilt all our bearings. We did three wheel alignment and corner weights before every race. We used more weight on the inside tire for the ovals. Our batteries were in their first year of racing.
Higher voltage is definitely an advantage. At twice the voltage, we were running half the current which means less losses.
I think our total package was better than what other people were running. There are a lot of clever people in our series so I suspect it will be harder this year. I know it will be fun.
Cliff is a friendly knowledgeable guy and a tough competitor. He has certainly made the rest of us bring our "A game" to the races!
We have been having this AC versus DC discussion among the EA board members and some interesting information has been brought to light. C. Michael Lewis sent the following links which seem to explore the subject pretty well:
From what I'm reading, the advantage of one system is offset by different advantages in the other, but the overall power/efficiency/etc. is virtually equal. The main difference is cost - AC systems are more complex and initially more expensive. It would be interesting if someone could install and test both systems in the same car with the same driver on the same track, etc. and publish the comparison results here. It would also be interesting to see a comparison between 24, 36, and 48 volt systems in the same car with the same motor, etc.
