This blog follows the progress of restoring and converting a 1973 Porsche 914 from stock to full electric drive, with an electric motor and half a ton of batteries. Now that the car is done and in storage while I live overseas, I'm adding descriptions and pictures of each Tesla location I visit.
It's been a long time since my last update because I haven't really worked on the 914 much, as there's little left to do on it. I take it out on the weekends for drives into town and around the back roads to my favorite winery. The next post will probably be from the Porsche club autocross in late April, and I've got the 914 entered so we'll see how she does against the gas boys.
I did feel the need to make a new post though, because I'm seeing Tesla Model S cars everywhere I go now. Maybe it's because I live in California but my little town of San Luis Obispo has at least 4 of them. Here's one that followed me into a restaurant parking lot a few weeks ago. The owner had just had it delivered the day before in Los Angeles and he was on his way north to visit family. That's 190 miles and he said he had about 75 miles of charge left, and it was all highway speed!
A few weeks ago I was working on the solar power monitoring system at three Costco stores in the Denver area when I realized the Tesla showroom was in a mall directly across the street from one of the Costcos. Ironically, it's located right across from the Apple Store, which was also designed by George Blankenship.
We talked about the article, the design of the Model S, the Roadster, the state of the company, how my shares were doing (up 30% thank you), my 914 and the electric-car-knowledge of the average person walking into the store. The guys were great with the people who came in, answering every question clearly and without bias, and dispelling every myth. They let everyone sit in it, and frankly I wouldn't have let some of them, but you never know who is going to grow up and be in the market in 10 years. When they were busy, folks would come over to me and start asking questions... I was quick to tell them that I wasn't an employee, but I did know a lot about the cars. Maybe I should consider applying for a job?
Most people who didn't know what a Tesla was were impressed with the body, the 17" display and the pure-electric design. Those who had a deeper understanding looked like they just walked into a candy store with an all-you-can-eat gift card. That's definitely how I felt, just being in the room. A few were dead-set against electric cars and it became quickly clear that no amount of fact could battle the brainwashing they'd been subject to. They just got in their 4x4 trucks and went to the gas station on the way home I guess.
As you can see, they had a production-line Model S, a trade-in Roadster with 4,000 miles on it for $70-$80K, and a rolling chassis with battery pack, transmission and motor. The chassis really helps people visualize the simplicity of the design - take this, add seats and a metal shell and you've pretty much got the car.
The staff said Tesla was a great company to work for, and I'm glad to hear that. One of the guys was an economics & marketing student who was very knowledgeable about the pros and cons of electric transportation.
After work the next day I went downtown, and saw this one on the top floor of a parking garage. They're everywhere!
Now we come to the Holy Grail of Teslas. What is a group of Teslas called? An Amp of Teslas? An Elon of Teslas? A Torque of Teslas? How about a car-hauler of Teslas! I was driving through the next town over of Atascadero California last Sunday, and I approached a car-hauler trailer parked on the side of the road. From a distance the tails of the cars look familiar. As I got closer I couldn't believe it. I pulled to the front and parked. There are 7 Tesla Model Ss on there!
There were two different models represented, designated by the badging on the rear. Here's a P85, meaning Performance model, 85 KWH battery pack.
Here's an 85, meaning standard performance, 85 KWH battery pack. That is a great-looking metallic silver, but alert readers will know I'm partial to that color...
Here they are from the front, a great selection of colors.
This was also my best opportunity yet to see the undercarriage of a real Model S, to see how they engineered the floorpan to minimize drag and maybe even increase downforce a la Formula 1. This is a shot from the rear of the car. You can see the black plastic undertray parts, which fit together to give a nearly seamless fit, then the silver bottom of the structural-member battery pack begins, running forward.
This is from the front, looking back. You can see the open areas around the lower parts of the front suspension, providing clearance for the up/down motion and tire pivoting.
Here's a closeup of the passenger side front wheel area. I wonder what those two access holes are for, and why they didn't bother to put a cover over them. Maybe they're drip holes for the air conditioning system?
Here's another angle of this area:
And here they are from the side. 3/4 of a million dollars worth of electric sex. The hauler was still there when I drove back down the street at 4 PM, so the driver must have spent the day in the area, then headed off to his deliveries on Monday morning. Ah, that really made my day.
Our Porsche club held the second autocross event at the Santa Maria airport track on October 6, 2012. You can find the details about the track and the first event here. I didn't bring my 914 down because it's a long haul on the trailer and I didn't know if there was a plug available for a top-off charge between sessions. I found out while I was there that there is a plug at the aerial firefighting station and perhaps I could get a plug at the Jet Center, so I'll think about it for next time.
The track had a different layout this time, with a full lap followed by a half-second lap which crossed over the return run to the finishing straight. With two cars on the track on each run, we joked that the crossing point was sponsored by Vintage Auto Body. Luckily, there were no accidents, but several cars forgot to make the turn on the second lap and were red flagged.
Here's a shot of the pit area, I think there were 40 - 50 cars in attendance, a lot of Porsches but also VWs, Subarus, Corvettes and others
There were 3 groups and while your car was not running you were assigned cone or flagging duty. Each group got 4 runs in the morning, and 3 runs in the afternoon as we were running out of time. This is the starting grid.
This is the very far end of the track with the big 180. This was my position as background-checked-and-certified-airport-TSA-security-for-the-day. I wanted to take a picture of my badge but didn't want to risk ending up in Guantanamo Bay.
Here's video of the most aggressive car making this turn, a bright red Turbo.
There were a blue and yellow 914, had to get a video of the blue one.
We had some spectators from the Jet Center and aerial firefighting station.
After the drag racing, autocrossing, dynamometer testing and socializing, attendees were a bit thin in the seats first thing on Saturday morning!
We kicked off with a roundtable discussion about electric boats with Anne Kloppenborg, Bill Denning, Jack and Jeff Southern.
Anne has completed a 1970s Glastron crusing/speed boat conversion project, in the Netherlands. It's great for both meandering around Amsterdam's harbor and canals and water skiing. He used Lithium batteries obviously and kept the Volvo-Penta stern drive via a custom-machined adapter plate. He's done extensive testing on energy usage at different speeds and at city speed he is pulling 1.3KW and can cruise for 20 hours on his battery pack, and in open water, peak power output is when he comes up on plane and then when on plane drops down to 41 KW. At top speed, it's pulling 86 KW, so a little more speed takes a great deal of additional power. Boats have a different driving style than cars, as they tend to go at slow speed to get out of the marina, then at constant high speed for extended periods of time, then slow again when you get to your destination. This may have a detrimental effect on EV-targeted motors unless sufficient cooling is implemented and a water-cooled motor would be natural in this application. Anne is now working on converting a 1950s Ray Wright Delta speedboat from a British company that made Spitfires in WW II. It's very small and fast!
Bill then spoke about a 40' boat project he's starting, making it out of Magnesium Oxide board, which is cheap and 4 times the strength of concrete.. He wants to do The Great Loop.
Jeff Southern then spoke about his history converting a dozen 5hp outboard motors to electric drive. Jack wants to convert an Aristocraft 14' speedboat and Jeff went to visit their factory outside Atlanta. Going with an electric boat will help as more and more restrictions are being placed on gas motor noise and pollution on lakes. Anne said that the Amsterdam is forcing tour companies to switch their boats from diesel over to electric. Jack and Anne believe that boat pricing is such that you can successfully put an electric drivetrain in a boat and make it still in the price range that people would expect, and the effective fuel cost is significantly lower.
Dave Hrivnak asked about the effects of salt water on electrical equipment and electrical safety issues with all of that water around. Nobody had any experience with salt water effects, but Anne said he got zapped when a wave came over his boat and he touched a wire that hadn't been properly mounted. Jack said that electrical safety on the water is a big issue and more effort needs to be put into waterproof packaging the components. Anne said one of his sub-packs got completely submerged in fresh water and there were no issues. Jeff said that he has seen no corrosion in an extensive fresh water environment. Jeff said electric boats work well in very cold temperatures when gasoline engines have a hard time starting.
George Hamstra from NetGain made an announcement about a new product, under development for 5 years. He has partnered with a large AC motor manufacturer, which supplies motors to along others Kia, Hyundai and Mercedes and trains, to bring 3 AC motors into the NetGain family. First is a 15KW-30KW 9,000 rpm air-cooled motor targeted to outboard motors. Next is a 30-60KW 9,000 rpm and 50-100KW 12,000 rpm liquid cooled motors. The controller they're partnering with the motors is a called ICPU which includes charger and J1772 plug and CANBus data connection. Pricing will be targeted at the same price as a current motor and controller. George had the unit under a black blanket so I will take a picture and put it here when the session is over. Update: Here they are, the motor is smaller than my WarP 9, and the controller is mounted on a huge finned heatsink. Not much detail yet, nothing on their web site.
Next up was a panel discussion on Driving the EV Business, with Jack, Sebastien Bourgois from Evnetics, George Hamstra from NetGain and Michael Bream from EV West.
George kicked off with a "presentation more dangerous than high voltage because it's about money, so use your common sense." The keys to success are hard work, dedication, knowledge (why we are all here at the show), drive, attitude, timing, luck (and making your own luck). The dirty work is inventory, AP, AR, balance sheet, customers (questions, phone calls and problems) and product documentation. You will need to do quarterly reports for potential business partners and banks. Steps to success are choosing the right business to be in (cost of startup), choosing a lawyer (and ask for his law school transcript), choose an accountant, choose a bank (check their lending limits and approval process), choose your employees (your most important asset). The Fear of Zeros is anxiety builds as the dollar amounts grow substantially, but you need to get over it and at large amounts the bank becomes your partner and wants you to succeed. If you're successful, you will accelerate so be ready for the ride and never drop the ball. To get rich, work for your own company, as your security, benefits and salary are up to you. The secret is to build the business with the intention of selling it off. You can then either retire and live the good life or start another company and do it all over again.
George then brought Jack, Sebastien and Michael into the discussion. Jack talked the Players and the rest of the population. Players are the innovators and serial entrepreneurs who are addicted to this kind of work. Find something you really like to do, aligned with a higher purpose, goal or mission. Do it a lot until you get good at it, and then people will pay you for it. Michael suggested finding a mentor, and the SCORE program can provide some valuable free advisors. Sebastien says that being the boss takes a great toll on you personally and he has to work twice as hard as everyone around him. Mark said he didn't have a business background, but he learned bookkeeping so he would understand what a good bookkeeper should be doing. Jack said he hired an accountant right from the start who did all reporting correctly which helped him in the end when he sold his business. Jack suggests that you plow all of your money back into the company in employee salary, R&D, capital expenses, etc. as this will reduce your taxable profits. George is concerned with his monthly outgoing money and projected monthly incoming money. The accountant will keep track of the details. Jack was concerned with daily cash balance, and he paid all of his bills on the day they were received, not 30 days later since that money belongs to somebody else. Some companies try to stretch their payables but that's a mistake.
Anne asked about how the panel handled bank and investor cash infusions. Michael said his first inflow was with a bank, and he built a personal relationship with the president of his bank. Sebastien took over a solar company with no clients and some debt, so he had to put in a tremendous amount of work for 3 to 5 years to get the company moving and then banks become interested. Jack said he started a business for $80 and sold it 11 years later for $38 million, without putting any more of his money into it. He stressed that it all comes down to selling, not matter how much innovation and hard work you do, it's all about taking in money from customers who want to give you money.
A question came up about feeling that weekends were getting in the way of running the business and Jack said he hates showering because it takes up valuable time. The board agreed that people with the drive succeed when they put in the effort. Jack likes to bring good people into his team and let them work hard and experience the excitement and process, and pay them well. Leaders exploit their skills and then hire people into the team to bring in missing skills until all pieces of the puzzle are in place. A point was made that a 1 - 15 person company can be mangaged by one person at the top, but anything above that requires layers of management and you have to be ready for the growth. Jack talked about plateaus, you get to a point and support that, then jump to the next one.
Andrew McClary told us about his experiences in the world of television and how it led to his new startup of a consumer-oriented hot rod electric conversion shop which will be supported by his video skills.
George said if you fail one time and quit, that's sad. Jack believes he can objectively analyze his failures and use that information for the next thing.
A question came up about product liability and George says he has Product Liability Insurance. Jack says he had to have insurance in certain circumstances, but avoids it when possible as it attracts lawsuits and lawwers.
We then headed down to the park for the public car show. Just a few pictures as I took a bunch of most of the same cars last year. A lot of interested people showed up to check out the cars and ask questions. Dave Hrivnak, with the blue Tesla Roadster, gave an interview to a young woman from college radio station, and then gave her a ride. She came back with the expected EV grin! I can't find a link to the interview, so if you find it, let me know.
We then drove in a police escorted parade through town back to the hotel, where we posed the cars and took some group pictures.
And a little video of the celebration!
After a short nap, we then headed back to the Show Me Center for the banquet and awards. I forgot to take pictures! At about midnight I stumbled back to the hotel to get some much needed sleep before leaving for the airport in the morning.
One thing to note is Jack did not announce EVCCON 2013! He discussed this in the video he released after the show, saying he took a loss on the show again and isn't sure if it's worth the time and effort, and if it should stay in the same format or change. Richard wants people to call him and give him support to run it again. Keep watching EVTV to see how things firm up.
After sleeping through my alarm for 30 minutes, I arrived at the Show Me Center just as Wayne Alexander was starting his session on EV conversions as a business.
He regaled us with pictures and descriptions of a half-done Mazda project he took over. Literally everything was wrong, so he showed us how he fixed everything and rebuilt it back to a working car. Then he moved to a Jeep project that had been worked on for 17 months and abandoned. The work was so bad it was actually dangerous, with the possibility of fire and shorting of the battery pack conductors to the drive shaft. He showed us his method of mounting non-electronic automatic transmissions to the motor. He likes to mount the controller, contactor and associated electrical parts on a thick sheet of Lexan and mount it above the motor under the front hood. He makes his battery boxes out of 1/8" steel. He suggests that you work on every car that comes across your path, don't be afraid to try new things, but try to standardize on a small set of components that you know and trust. Simplicity is best, as it leads to fast builds and working EVs. He stressed that we have to do conversions well because one bad car will taint our whole industry.
Next up was David Kerzel on charging port issues for J1772.
He started by talking about electrical safety, as there is a perception that gasoline is safer than electricity, but there were 250,000 gasoline car fires and a handful of electrics. The J1772 standard brings together a common connector and an electrical safety protocol. The connector has a well-thought-out design, with no exposed wiring, ground mates first, the proximity switch engages and then the 3-stage safety protocol happens to ensure the car is ready to be charged, then power starts flowing.
J1772 Level 1 is normally 12 amps at 120V. You can normally get 6 hours per mile of charging time.
J1772 Level 2 is normally 23 amps at 240V, giving 27 miles per hour of charge. A few 80 amp charging stations exist which will give about 93 miles per hour of charge.
J1772 Level 3 is a completely different beast. It is high-current DC power rather than AC power. It bypasses the charger in the car and dumps power directly into the battery pack, matching voltages as necessary. Nissan Leafs are equipped with CHAdeMo, which handles 500V DC at 125 amps. SAE is working on a J1772 standard, which adds two large posts for DC onto the bottom of a Level 1/2 connector. It is expected to handle 600V DC at 200 amps. The safety protocol has not been determined yet. This system has been accepted by GM, Chrysler, Ford, Toyota, Honda, Nissan and Tesla. No production cars use this yet.
Why are EVSEs (Electric Vehicle Service Equipment, what most people call a charging station) so expensive? First, is safety, as the connectors and wires must pass strict rules. Then the units have to be robust to handle years of charging, weather, vandalism, etc.
The Tesla Supercharger network was just announced this week. Tesla says it is a 90 KW/hour system, taking 20 minutes to charge for a 3 hour drive, but David's calculations show a 20 minute charge will actually take a Tesla Model S about 80 miles. With all 6 charging bays in operation, that will pull over 500,000 watts of power, as much as my company installs on the roof of a Costco store. David wonders if the charging will always be free and doubts the $250,000 construction cost quoted by Tesla.
David says when you find a public EVSE, check it over for damage and try to notify someone if it needs attention. What do you do when a non-electric car is parked in the spot? Be polite and move your car when done charging and coil up the cable nicely.
David worked through different adapter cable scenarios. It's important to remember that J1772 connectors are not rated to plug and unplug when energized! There are several EVSE open source projects on the Internet using Arduino controllers. David sells his 4th generation EVSE controller and display unit as a kit. Data connections are important for commercial customers as they want to know how much power and how many cars are being charged, as it's essentially an advertising cost to the business. If you buy a fully-assembled EVSE it must be UL listed, but if you buy it as a kit, your electrical inspector must approve it, following National Electrical Code Section 625.
David discussed his future plans which include GFI integrated into his products, adding soft current limit, timers and communications to cell phone for commands, settings and statistics.
Next up was Steve Woodruff, talking about his Prius plug-in kit and finding parts to build your EV.
Steve competed in the 2009 X-Prize competition with a heavily modified Prius. His primary business is to recycle parts from damaged Priuses (Prii?). He built a stretch Prius plug-in limo. He supplies repaired Prius touchscreens, shift levers, cables, battery cells or packs, and sells his own supplemental plug-in battery pack.
His tip is to buy the whole wrecked vehicle, as all of the parts can eventually be salvaged. You can get leads on cars through insurance company auctions, Copart auctions and Mannheim auctions. Always bid assuming there is more damage than you can see. You need to be registered as a vehicle dealer and your buyer fee will be $495 and 90c / mile shipping. If the car has a Certificate of Destruction or Junk title the car cannot be rebuilt, only sold for parts.
A Prius has a 1.5 liter Atkinson cycle engine, which means all 4 cycles of the engine are completed in one turn of the crankshaft rather than the standard two. There are two large generators in the drivetrain and an AC motor. It has a continually variable transmission that merges the power from the engine and motor. He prefers to work on the Generation 2 Prius model although Generation 3s are on the road today.
The Prius doesn't have a power steering pump, belt-driven AC compressor or alternator and no starter motor. This is a big difference between traditional engines. There are 28 Nickel-Metal-Hydride cells in the pack which are built into a slab.
There are a couple of other Prius plug-in conversion shops around. Steve has 22 conversions on the road. A Prius requires about 1 KWH to move 3 miles so a large 10KWH plug-in upgrade will allow for 30 miles under electric power, then reverts to normal Prius mode. Steve has also rebuilt several Prius built-in battery packs and has only had one come back with a repeat failure, and Steve stood behind it with a warranty. It costs about 1/3 of a new pack, so customers are willing to take the chance. He matches the voltage of the replacement cells with the state of the existing pack to avoid bottom balancing issues.
The key to making a plug-in pack work is that the Toyota software has been hacked to allow for the car to go to at higher speeds in electric mode than was originally designed.
Keegan Han from CALB batteries was supposed to be a speaker, but his parents arrived from China and cancelled his appearance.
Next up was Rich Rudman from Manzanita Micro, maker of chargers and motor controllers.
Rich has a long history in the EV world with chargers, controllers and battery management systens. His first electric car was a Ford Fiesta drag racer. The first charger was the PFC-20 which could take 120V or 240V AC. The PFC-50 came next which would take in up to 50A, giving 10KW of power. Then the PFC-75 came with up to 20KW of power. These chargers must be run in a cool environment or they will overheat and derate the output. New models are coming out with a new enclosure and dial-wheel voltage adjustment. A new meter shows input voltage, current, KW and power factor. Additionally they will directly support J1772 protocols.
The Zilla controller is legendary and has gone through a lot of turbulence of owners. Rich now owns the Zilla product and has brought it back into production. He is building the current version now and has several enhancements planned for early next year. The Zilla 1K unit is a compact water-cooled unit running 1000A. The Zilla 2K unit handles 2000A. They also have a limited edition Zilla 4K unit. The Hairball unit moves all of the input signaling out of the main controller box to avoid costly failures.
They offered a BMS system staring in 2008. He feels strongly that BMSs are required and top-balancing is the only solution to pack setup. This is in violent disagreement with Jack. He also said that all Lithium battery manufacturers require a BMS or the warranty is void. He showed a screenshot of his display which gives a good view of the behavior of each battery, whether he is regulating the top charge or not. The question came up about running a small wire to each cell, and Rich said it's an issue but solvable with circuit-board solutions, properly bundling wires, etc. and they have not had any failures that weren't traced to installer error.
There was a lively discussion about dissipation of energy during charging shunting phase and throttling back the charger.
A quick break for lunch and we're back for Tom Brunka and his session on The Helwig Carbon Brush in your Series DC EV Motor. Tom's was the blockbuster session last year, with lots of great information about motor brush compounds and construction and the direct effect they have on your performance and range. Jack did extensive testing of the split Red Top brush design and Tim found his range was extended by more than 10% just by swapping brushes.
Tom gave us a video tour of his factory. They manufacture not only brushes but brush holders and constant force springs. There are 3 different grades of materials
Electro-Graphite: High end, used in EVs
Metal Graphite: up to 48V DC
Graphite: up to 90V DC
Within these types, there are many grades, with different levels of resistivity, strength, hardness, friction and filming, leading to different brushes designed for different applications. Brushes are sized based on current density.
H38: Up to 80A per square inch, long life for street EV usage
H49: Up to 100A per square inch, untreated for racing
H60 Up to 80A per square inch, street EV usage
K254: Below 80A per square inch
The film is an important part of motor operation. It builds up on the commutator and acts as a dry lubricant allowing the brushes to glide over smoothly. It should be a nice dark brown color without arcing indications. Resistance comes into play as it affects the temperature that the brush runs at. Tamping material can be copper or graphite and bonds the shunt wire to the brush.
Brush wear factors include mechanical friction, electrical arcing, spring force, humidity (helps to create and maintain the film) and commutator wear. The target spring force for most electric motors is 4 psi at the brush face, in an EV the minimum should be 8 psi due to bouncing and vibration. You can add one-half to one more bend on the brush spring to gain a bit more brush force. A sign of not enough brush force is marks on the face of the brush. Better contact means better electricity transfer and efficiency and therefore less heat.
Arcing has many sources, including the advance/retard of the motor timing, contact area, roundness of the commutator leading to the brush bouncing right off, spring force and heat soak.
Helwig suggests seating the brush to 80% before using it in a normal application. This can result in running the motor on a 12V battery in neutral at 3000 rpm for several days. H49 seats quickest in 6-15 hours, H60 seats in 6-7 days, H38 seats in 17 days! They suggest beveling each commutator bar at 45 degrees, then lathe cut it round, then polish with 80 grit and 150 grit garnet paper only.
They suggest using a Grounding Brush Kit due to inducing of current into the bearings and the driveshaft. One customer read 20A being drained off after installing one of these kits.
As the brushes wear, they turn to dust and can lodge inside the motor, starting a frame leak. Blowing the motor out 4 times per year is a good rule of thumb. It's also a safety precaution to add an active blower to your motor, which helps with cooling and cleaning out brush dust.
Never use silicone spray, grease or sealer in the vicinity of a DC motor, as it will contaminate and attack the brushes due to the conversion to Silicon Carbide.
Acetone is the preferred cleaning solution, but make sure it's completely removed as it's highly flammable.
New developments on the horizon include new manufacturing processes and grades of brushes to meet the needs of the market. They are looking at larger shunt wires, tamping materials, higher current handling by adding silver (but expensive) and new brush holder designs.
A question came up about overheating EV motors due to the nature of driving. Tom suggested adding blowers to keep the motor and brushes cool, they must be below 400F. As a science experiment you can drill a hole in a brush and epoxy in a thermocouple to directly measure brush temperature.
There should be an ink stamped part number on the side of each brush for easy identification if you're repairing or upgrading a motor.
Tom says they use a fish scale as a crude way to measuring spring pressure in the field.
The last speaker for the day is John Hardy from the UK. He has contributed videos to EVTV and is speaking on battery testing.
John has a varied background as an engineer, car accident analyst and commercial pilot.
Why do we test batteries? There is little data, so it was a job that needed doing and he wanted to do an electric car conversion and wanted to make sure he picked the right batteries and charged and discharged them properly.
The conventional wisdom held that batteries drift apart in voltage in a pack and you need a BMS, so he wanted to use science to see if that is actually true. There is a lot of data out there about Lead Acid cells, strings and batteries. They self-discharge just by sitting there, called the Peukert Effect. Many people seem to think that these principles carry over to other battery chemistries. Lithium Iron Phosphate batteries do not self-discharge, but there is little additional data or analysis.
John built a test rig with a charger, a load and a series of Headway LiFePO4 round cells, and used an Arduino controller to manage his test processes. His voltage measurement tool consumes 0.2 ma which has a non-trivial effect on the pack, so he added an OpAmp to isolate the metering from the pack. He used a language called "Processing" and a cloud data service called Pachube and CSV files into Dropbox to collect and store the data. He then pulls the data and graphs it.
After months of 3C charge and discharge cycles, his results indicate he saw almost no variation between cells at the end of the discharge cycle from his bottom balancing variation, but a small amount of variation around 6 mV between cells during the constant voltage phase of the charge cycle. By removing the constant voltage charging phase, the cells had nearly zero variance throughout the charge and discharge cycles. He then added a "top-up" charge after 5 minutes of rest after the constant current charging phase with a tiny variance, then a "double-top-up" charge, with a slightly larger variance, of about 3 mV. At a lower charging rate of 1C, the pattern remained the same.
The bottom line is there was 10 mv, or 0.3% discernable drift between cells, no matter what the charging cycle or charge and discharge rates. This is as close to zero as is measurable. So John has shown that there is no risk of Lithium cell drift in a pack. As long as the cells are bottom balanced at the time of installation, they will behave beautifully through their lifecycle. He did have one cell fail around cycle 575, so this needs to be taken into account to detect a failed cell in a pack.
He is going to do another test with CALB cells to see if they also hold up to this profile.
We all packed up and headed over to the airport for 1/4 mile drag racing, autocrossing and dynamometer testing!
This is Jack's hanger at the airport, where the food, drinks and portable dynamometer machine were housed. Normally there are two DC3 aircraft parked here, along with Jack's collection of MGs you can see below.
Here's a closeup of the portable dynamometer. Jack paid for it, and it was free to anyone to use for 2 or 3 runs.
The cars started to get staged outside, in preparation for SCCA-sanctioned 1/4 mile drag racing, starting with the weigh-in.
Ron Adamowicz, with his last pennies, brought his unbelievable dragster to the event. Now the hood is off here, so it's hard to picture, but this is the size and shape of a Funny Car.
It has two 11" DC motors, 2 lithium battery backs and two Evnetics Shiva motor controllers. I mentioned earlier that each Shiva can pour 3000 Amps and 1.2 million watts of power into a motor. Now just imagine that Ron's car has *two* of them. That's 2.4 million watts of power. Boggles the mind. Check out his two runs in the drag racing video below.
Here is Fred Behning's gorgeous completed-just-in-time-to-put-on-the-trailer MG TD. He won the trophy for Best Paint at the awards ceremony.
Alex Smith's Wrightspeed lookalike looked insanely fast but was held back by its lead-acid batteries, same as my 914. With a lithium pack, this car could beat the Teslas.
Doug Ingraham's RX7 looked fast.
Holding the torch for the 914 brigade was Mark Emon with a crazy 56 200AH lithium cells. After finishing his build at home, he drove it 2 blocks then put it into the truck and drove to the show. He spent arrival day in Jack's shop finishing up details like replacing his coolant pump and hooking up the charger wiring.
Next up was Kevin Heath's RX8. Kevin picked up 3 trophies at the award ceremony for this fantastic car, with a battery pack made from A123 lithium pouch cells.
We got to watch John Allan build this Celica via videos he would record then send to Jack for inclusion in an EVTV episode.
This is Norbert Kedzierski's Boxster. His company, Red Point Engineering, among other cool things makes electric conversion kits for Boxsters. It is his daughter's 7th birthday today and she didn't seem to mind spending time with the electric cars.
This is Stella Kostolina's and Zachary Vex's Tesla Roadster Performance machine. It's black on black on black and looks amazing and goes even better. Stella and Zachary are making a reality TV show called Electric Trippers which follows their journey as they drive around the country, meet interesting people and try to find places to plug in.
Here is Jack's Porsche 550 Spyder replica. It used to be owned by Duane Ball, but Jack bought it when Duane decided to go ahead with his Porsche 904 replica project.
Here's the race start position. The helicopter is not for emergency flights to the hospital!
I got most of the cars racing on the drag strip.
Fred let me take his MG TD for a couple of runs, here is the video:
These are my two run slips. The first run was good, with a 19.489 quarter-mile time, at 62.5 mph.
The second run was worse, as in my enthusiasm I knocked the throttle linkage off the pedal when shifting into 3rd gear. I had to reach down and push it back into place, hampering my time to 23.555 seconds and 49.3 mph...
The autocross track was open and most cars headed over after doing a couple of drag strip runs. Here's a video of Charlie and Tamera in the Opel GT.
As the sun set, most people brought their cars over to the dynamometer test rig. Here's Charlie's run in the Opel GT.
And his graph shows he's making 104 horsepower, which is excellent for such a light car.
Then Mark's 914 with the enormous battery pack was on the ramp.
Then Caleb Lander got his 1974 Super Beetle up on the ramp.
It has a relatively small lithium pack but made a brave 39 horsepower.
Then things got very interesting when the Evnetics team got Sebastien's 911 ready for testing. The first two runs actually had a controller shutdown because the 12V power bus voltage was too high. They solved the problem by turning on the headlights!
And turned in an amazing 356 horsepower!
Next was Stella and Zachary's Tesla.
That's 256 horsepower.
Last up for the day was Jack in the Speedster, a sleeper of a car with a large pack and surprising power.
That's 160 horsepower, folks. About twice what most of the original cars left the factory with.
After things wrapped up here, a group of us went to a local bar and enjoyed ourselves thoroughly. Got to bed about 2 AM...
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