Wednesday, October 26, 2011

EVCCON 2011 Day 2

The sun rose on Friday to a lot of exhausted electric car people.  It was full of sessions and I took a lot of notes, so let's dive in.


First up was Paul Lin, founder of Aptima Motors in Taiwan.    He's designed a trash-collecting tricycle, electric sailboats, an eScooter, electric trains for the Taipei subway system and 40KW lithium electric ferry boats.  He launched the eCobra project with Jack and Brian.

He said that the Chinese luxury car market is nearly the same as the US, but the owners are 14 years younger, so the market for upscale cars is there.  He also sees city cars, with a stop/start and low speed profile, ramping up.  Electric taxis are in fleet testing right now.  They have a modular, replaceable battery pack system.  The taxi returns to the depot, several suitacase-sized battery packs are removed and replaced with fully-charges units waiting.  The back seat tips up, allowing access to the battery bay. It takes about 2 minutes to do a swap, much faster than charging.  The battery packs are owned and maintained by the electric utility.

Very few electric cars are personally owned in Asia.  Most are corporate fleet or utility owned.  People have seen reports of a few fires and are a little apprehensive.  This may have been the result of Battery Management Systems (BMS) problems, such as overcharging, as we have also seen multiple cases of battery fires in other parts of the world.


Next up was Bill Ritchie from HPEV - High Performance Electric Vehicles.  HPEV winds their own motors and developed the first sub-$5000 AC drive train EV conversion solution.  Their early work was with Curtis motor controllers.  One system they were testing broke off the dyno and went through a nearby door.  They have built hundreds of electric drivetrains for golf carts and NEV - Neighbourhood Electric Vehicles - for Palm Springs, California.  They worked with Rousch Engineering on a Ford delivery truck but were blocked from sale by the NHTSA.  They did a VW Jetta conversion with two motors on one shaft and two AC controllers.

They built the Wheego drive system, running 8500  rpm at 70 mph.  It has 36 260AH batteries with a 100 mile range.

Their AC motor is used in Jack's Speedster and Spyder and the 904.  They've put it into everything from a VW Beetle to a Ford Ranger truck, anything up to 3000 lbs.

They offer several regenerative braking modes: neutral braking, brake pad potentiometer and brake fluid pressure sensor.  They have CANBus integration, with chargers, controllers and instruments.  Soon they will offer a liquid cooled 9" AC motor paired with a 144V Curtis controller.


Next up was Dr. Dennis Doerffel from REAPsystems.  Dennis did his Doctoral thesis on "Testing and Characterization of Large High Energy Lithium Ion Batteries for Electric and Hybrid Electric Vehicles."  He's the right guy for this audience!  REAPsystems consults on vehicle battery systems and has built a modular BMS.

He has converted a VW Golf, Honda Insight, ThinkCity anf Ford Fiesta.  He is the founder and moderator of the Yahoo group dealing with Thundersky batteries.

During his car conversion and PhD program, he decided he needed a BMS to check the state on every battery, so he founded REAPsystems in 2003 and built a Lithium Ion BMS.  His prototype EV runs 5000 euros plus batteries.  He's worked on Minis, taxi minivans, motorcycles, solar racing cars, airships, America's Cup yachts, underwater vehicles, boats and worked with Maclaren on the KERS system on their Formula 1 car!

One of his big goals is to prevent battery fires and there are a lot of factors that go into measuring the health of a battery pack: cell balance, charge/discharge rates, regeneration, thermal management, maximizing life, maximizing performance and range, driver information, diagnostics, adaptability, and CANbus integration with all devices.

His BMS module can manage 14 cells, and you can put up to 12 modules per system.  His battery control unit handles precharge, and drives contactor, heater, pump, fan, and compressor.

He then began discussing battery chemistry, starting with lead-acid (Pb).  Lead batteries have the "Peukert Effect" - self-discharge.  Lithium batteries have no self-discharge issues, even when sitting for 2 years in a shipping box, as Jack demonstrated.  In fact, high-discharge of lithium batteries can increase capacity due to the temperature increase.

Lithium charge and discharge voltages are different, and is therefore not a reliable way to measure State of charge (SOC), but after 48 hours of rest, come back to within 11mv so it's very close.  Impedance has a complex behaviour, so it's not suitable for SOC either.  Cold discharge has a bad effect on voltage, it can drop below the rated minimums, so it's best to keep the batteries within the rated temperature range.

Dennis then challenged the crowd.  If you have hate / love / ideas, send them to evccon@reapssytems.com, with subject Challenge.  If you want to participate in his efforts, email with subject "Cell Testing".  If you're an integrator or VAR, email with subject "Integrator" or "VAR".

In the end, he said amp-hour counting in and out of the pack is the best SOC metric.  You will need to reset your AH counter at the end of charge.


Next up was Dr. Valery Miftakov, founder and CEO of Electric Motor Werks.  He specializes in high end electric conversions on BMWs.  With an MS and PhD in Physics, and the two-time winner of the Russian Physics Olympics, he's got a lot of brainpower to throw at the problem.

His niche is high-volume BMW conversions with standardized parts and processes for efficiency, plus his own component design as needed.  His research find his potential customer base is interested in acceleration, recharge time and fun / cool factor.  His cars do 0-60 in less than 6 seconds with 100+ mile range at freeway speeds, topping out at over 100 mph.  His conversions cost roughly $20K and is hoping to get down to $15K as his quantities rise.  Remember, these are BMW owners and they expect performance and are willing to pay for it.

He's going to introduce his first conversion at the EV Rally in Palo Alto tomorrow.  He needs parts suppliers but he finds most things have a closed architecture and therefore technical dead-ends.  He wants to work on an open-specification set of parts for charger, controller and instrumentation.

Then we headed to lunch and more time outside with the cars!  I grabbed some shots of Jack's Mini Cooper.



A bit of a tangle of wires...


We were herded back into the hanger for David Kerzel's session on EV charging.  He launched Modular EV Power, which specializes in EV charging connectors and related parts.  He taught us everything there is to know about the J1772 connector and some others on the market.

The J1772 connector is the new standard for EV charging.  It's a polarized design so it can only be installed in one way.  It is touch-safe as the wires are all shrouded from contact, it prevents accidental disconnection with a toggle switch latch, has a ground conductor which mates in the socket first for additional safety.

There are 3 "levels" of charging defined:

Level 1: 120V at less than 16A, but typically 12A.  This delivers 1440W per hour to the pack.  At 200W of power consumption per mile, that translates to 6 miles of energy delivery per hour.  You can see that this isn't very practical for most EVs with large battery packs, but is OK for small packs, NEVs, golf carts, etc.  In this case, only one hot leg and ground are wired to the connector, while the other hot leg is left unconnected.  This allows a Level 2-capable charger to charge a Level 1 car, which is my situation for Version 1 of my 914.

Level 2: 208/240V at 6-80A, but typically 23A due to the rating of the J1772 connectors on the market today.  This delivers 5500W per hour to the pack.  At 200W of power consumption per mile, that translates to 27 miles of energy delivery per hour, or 90 miles of energy at the highest current rating of 80A.

Level 3: DC bulk charging.  There is very little of this technology available due to the need for the charger to exist outside the car, and delivery hundreds of amps of current.

EVSE, or Electric Vehicle Supply Equipment, is the technical name for a smart charger incorporating a J1772 connector.  The smart part of the system comes from two extra pins in the connector, besides the big pins delivering power.  The Pilot signal wire allows for a conversation between the car and the charger.  When the wire has a +12V signal, it means the connector is not plugged in.  At +9V, it means the connector is plugged in and ready.  At +6V it means the system is charging.  A 1Khz square wave signal on the pilot signal allows for even more control, indicating the the amount of current available for delivery.  Luckily, it only takes a few cheap components to make this conversation viable in the car and charger.  Finally there is a Proximity pin, which is only connected on the car side that indicates when the latch button is engaged in the connector.  This is only sometimes used.

There is an existing connector from Japan called CHAdeMO, which means "Charge To Move".  It delivers the equivalent of J1772 Level 3, with bulk DC charging right into the battery pack.  It's used by Nissan in the Leaf, Renault and TEPCO in Japan.  It's spec'd up to 1000V and 400A.  That is a metric ton of power being dumped into the battery pack.  Luckily a Lithium ion pack can handle it!

Last up for the day was Ryan Bohm, from EVSource and NetGain Controls.  NetGain's controllers are jumping into the market with some serious equipment.  They handle 160V at 1000A and 360V at 1400A.  They're liquid cooled and CANbus enabled.

He went into what DC motors are looking for from their controller.  They want to spin at a certain RPM for a given voltage, on a straight line.  As load is applied, more current is drawn to get back to and sustain the desired RPM.

Continuous current should be delivered at about 1/3 of peak.  Peak current should be delivered only for a few seconds at most.  Liquid cooling will help this, but there is a definite physical limit.

CANbus enablement is key, driving instruments, controllers, throttle systems, etc.

Safety is key in your project - build in redundancy for failure modes, make a plan for your build, use insulated tools, use one hand in the naughty bits.

Build with quality - plan your layout, use good wire connectors and heat shrink tubing, bundle your wires into wire loom, etc.

After this full day of sessions, we went outside to the drag strip and autocross track.  Members of the public were invited to watch and dozens showed up and enjoyed the late afternoon excitement that went until dusk made us wrap things up.  I took a bunch of pictures and videos, so enjoy the following!  The local Sports Car Club of America (SCCA) set up the 1/4 mile track and a great autocross track (with running commentary!), timing equipment and said that everyone with an electric car had to make at least one 1/4 mile run and autocross run.

Here's Richard rolling up to the weigh station for his speed run!


Here is Richard going up against Jack's Porsche Spyder.



Here are Jason Horak in his Daytona and Tim Catellier in his BMW Z3.


Here's Duane Ball in his Porsche 904 and Eric Kriss in his Porsche Speedster.


And here's a video of them in action.



Here are Daniel Yohannes in his Cayenne and Jim Hanna in his VW pickup.
 

Here are Kevin Smith in the custom "Seven" and Steve Woodruff in the stretch Prius.


David Hrvak is on the weigh station in his Tesla Roadster.


Tamera and Charlie Rickman's Opel GT on the weigh station.


And here are Charlie and David on their first run.  Charlie's car is great, but the Tesla is simply breathtaking.  David took many, many people for runs through the afternoon and hit 100mph at the end of each run.



Fred is staging for his run.  With his English driving cap, he was more out for a country drive than a record-setting run.


Next up were a Geo Metro (sorry don't know the name) and John Yecker's Ford Ranger.


Next was a bit of a lopsided contest with Sebastien Bourgeois' dual-motor Porsche 911 and Michel Bondy's Subaru Forester.  I can say that Michel's clutch did survive the weekend; can't say the same for the 911...


You can almost smell the clutch in the video.



The eventual winner of the drag racing is Ronald Adamowicz's custom-built WarpFactor II dragster built on a 1981 Chevy Camaro chassis.    This car runs a 10 second 1/4 mile, which compares with Porsche 911 Turbos and Corvette Z06s.


After dark, we decided to go over to Jack's house and have the bonfire and some home-distilled whiskey.



Well that was a very long, action packed day.  Late that night I crawled back to the hotel to get a few hours of sleep.