August, 2007

Taking a Break

Porsche 914 EV Conversion

These last few days have packed with non-EV stuff, but I did take the DC-DC controller into the lab to see what was going on. First of all, there are no kick-back diodes on the inductors inside the converter. This kinda scares me since pulling on an inductor with a FET and then letting it go tends to create really high voltages (> 600V etc.). I hacked together a 160V DC power source by simply tapping off the bulk capacitor inside one of our power supplies.

2007 100

The 60,000 Volt Question

Plug In Partners

I f there is any doubt that GM is serious about PHEVs, here is one more story that indicates that they are indeed very serious. GM Could Reportedly Produce 60,000 Plug-in Hybrids in 2010 Source: GreenBiz.com by Jeff Green at Bloomberg OAKLAND, Calif., 23, 2007 -- General Motors Corp. could reportedly produce up to 60,000 Volt electric cars in 2010 , its first anticipated year on the market.

2007 100
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Coal Into Cars: The Good, the Bad, the Ugly

Plugs and Cars

The Ugly Coal sucks, there's really no two ways about it. Extracting it is ruinous of the landscape and burning it has disastrous environmental consequences. It should be perhaps our last fuel of choice regardless of how it's used. But not all use of coal is alike. The Good About half our electricity comes from coal, and that will change, at best, slowly as we move to renewables.

2007 100

PakTrakr is Online! DC-DC blown again.

Porsche 914 EV Conversion

I spent most of yesterday and a few hours today wiring up the PakTrakr system. It's a bit of a pain to disconnect the most negative lead before attaching the display, but that's minor nuisance. It seems to measure pack voltage well; however, the voltage measurement on each battery seems to be slightly inaccurate. The Zivan charger is balancing the batteries well and each of them is within an 8.48V-8.50V range (20mv difference is pretty good!).

2007 100

Talking with Mike at ElectroAuto

Porsche 914 EV Conversion

I just got off the phone with Mike at Electro Automotive. We chatted about the blown CCPower DC-DC converter and the engine vibrations. Since I fixed the DC-DC converter, we agreed that I would try to find out which conditions would cause it to blow again, if it does. It seems that Mike is more of a mechanical person than an electronics person. He graciously faxed me a circuit to generate a tach pulse from an ADC8" or 9" motor, but he didn't really understand the circuit.

2007 100

EV Toolbox

Porsche 914 EV Conversion

Before the accessory battery discharge yesterday, I wrote down a list of things to keep in the EV in case there was a breakdown out on the road. I came up with the following items. Any comments for additions or modifications would be welcome.

2007 100

DC/DC converter blown

Porsche 914 EV Conversion

Well, I ran out to Radio Shack this morning and got some more 5 amp fuses for the DC/DC converter. After plugging a fast-blow fuse in, powering up the car blows the fuse. I tried a slow-blow fuse and that went too. I then disconnected the 12V battery to see if that was causing a problem and it still blew a fuse. What's sort of interesting is that these glass fuses didn't just melt and break, they really vaporized and completely coated the inside of the fuse glass with metal bits.

2007 100

More Trending

Fixing the DC-DC Converter

Porsche 914 EV Conversion

I cringe at the thought of having to send anything back to Electro Automotive for replacement or repair, so I took a chance and dissected the DC-DC converter to see if I could fix it. The company that makes the DC-DC converter is CC-Power in the UK, so I don't think sending it back to them would be timely either. Here's the DC-DC converter taken out of its black aluminum case.

2007 100

Commuting.

Porsche 914 EV Conversion

Despite the issues with the car, I've decided to start commuting 15 miles each way to work to see how the car does. By not revving the motor above 5000RPM, I can minimize the vibration problem. The batteries are starting to break in. I'm getting slightly more power on the freeway now and starting from a dead stop is acceptable. I've taken the 914 up to 70mph. It doesn't have the pep that the original 2.0

2007 100

12V Auxilliary Battery Dies!

Porsche 914 EV Conversion

While cruising over to my girlfriend's house this evening, the whole system just shut down on the road. That was a rather scary experience. The hazard signals started flickering and nothing would turn on. After pulling over and checking the voltage on everything, the pack was nicely up at 150V but the accessory battery was down to 10.5 volts. With the key on, the DC-DC converter light was on; however, when I checked the DC-DC fuse, it was blown.

2007 100

EV Briefs, and Black Rock City & EVs

Plugs and Cars

A few items before I head out to Black Rock City for two weeks. Out in the desert as part of Burning Man , our encampment, Snow Koan Solar, is setting up a solar photovoltaic EV Charging Station (at 7:30 and Desert) for electric scooters, golf carts, sofas and barstools. We'll also be taking Burning Man art projects off petroleum generators by switching them to solar electricity.

2007 100

Fixing the Flywheel - Still Vibrations!

Porsche 914 EV Conversion

This has been one heck of a week. I took the flywheel into an automotive machine shop to balance along with the attached clutch assembly. In the meantime, I tried to figure out if the real problem was the motor to flywheel adapter from Electro Automotive. I borrowed a precision dial gauge from a coworker and measured the wobble on the motor adapter. Initially, it had a full 7 mils (thousandths of an inch) of difference in depth.

2007 100

Grommets Anyone?

Porsche 914 EV Conversion

In my frustration to take care of the vibrating of the motor/tranny, I unbolted the motor from the front engine mount and raised it up with a jack. The clearance above the motor is tight so you can't raise it too much. After revving up the motor, it still resonates at 5000 RPM which leads me to believe that there's an issue with the motor to transmission coupling. If the transmission shaft is slightly off center then the whole thing could wobble.

2007 100

NEDRA Pictures

Porsche 914 EV Conversion

Going to NEDRA at Portland International Raceway was my first major excursion in the 914 since both the flywheel was balanced and the clutch was properly adjusted. The car handled very well and cruised on the freeway without much problem. I did get up to 65 but kept my speed mostly at 50 to not pull too much current while breaking in the batteries. Here's the wait in line for the ticket office at Portland International Raceway. I felt proud to not have to waste gas while idling in line.

2007 100

The Plug In Scooter

Plug In Partners

G enerally, when we talk about Plug Ins , we think about automobiles. And there has been some big news on that front in the last few weeks. Toyota has now moved to have a plug-in approved in Japan and will test them on California campuses. Meanwhile GM is actively moving forward on the Volt. But there are other embodiments of plug in technology. This one might become a real favorite.

2007 100

Taking a Day off to see the EV Show

Porsche 914 EV Conversion

I took the day off to walk around Portland to the farmers market and EV awareness day with Krista. There were probably twenty electric vehicles at EV awareness day. Here are just a few of the more notable ones. The electrically augmented bicycle. This was originally just a human powered vehicle made in Belgium, but the owner added an electric motor to power the rear third wheel to get up the hills in Portland (of which there aren't many in Belgium).

2007 100

Balancing the Flywheel/Clutch

Porsche 914 EV Conversion

Okay, since I take Fridays off, this gives me a chance to take the flywheel into a machine shop for balancing. I took the flywheel and clutch pressure plate to Portland Engine Rebuilders. They basically said that they couldn't balance the flywheel because they couldn't attach their balancing machine to the small center hole. Many thanks to Alan at A&P Specialties (Audi and Porsche repair) for lending me a 1.7Liter 914 crankshaft so I could provide something for P.E.R. to balance.

2007 100

PakTrakr Arrives and Adapter Misaligned

Porsche 914 EV Conversion

Well, this day definitely had its ups and downs. The PakTrakr battery monitoring system I was expecting early next week actually showed up today. Here's the PakTrakr still in all its bags. The main display and one battery monitor unit is in the upper-left bag. Three extension battery monitors are in the other three bags. The serial cable in the lower left can hold 2MBytes of log data before dumping it down to a laptop. Each monitor can handle six batteries.

2007 100

Biting the Bullet - Book 2

Porsche 914 EV Conversion

In my eagerness to balance the flywheel, I unhooked all the mechanical and electrical cables from the motor/transmission assembly and lowered it onto a furniture dolly. Note that I still need to borrow the CV joint bolt remover from Craig at Camp914, so the assembly is just sitting on the floor right now. I'll try to describe the process in a little detail since Joe posted a comment a few hours ago asking for more pictures. First up was removing all the mechanical cables.

2007 100

Swallowing my Ego

Porsche 914 EV Conversion

Over the past few days, I've gone through the four stages of acceptance regarding the rather noisy vibration that the car undergoes when I rev the motor above 3500 RPM. Denial: "My new electric car is wonderful and it doesn't really rattle above 3500 RPM." Anger: "Why the hell does my car vibrate and rattle about 3500 RPM???!! It's not supposed to do that! Can't the Porsche folks make a good flywheel? Can't ElectroAuto make a good adapter coupling?"

2007 100

Shifting Fixed and Charger Outlet Installed

Porsche 914 EV Conversion

Things just keep getting better and better with this car. I did some experiments this morning with operating the transmission and found that my clutch wasn't fully disengaging. After adjusting the clutch to fully release this evening, the car shifts MUCH better and I don't grind gears anymore! What a relief! I also took this evening to finish up the wiring for the external charging outlet on the front fender of the car. This means I don't have to open the hood to charge the car.

2007 100

Imagine the Volt

Plugs and Cars

Seventeen years ago GM could imagine, and then produce, an electric car. Check out this 13 minute GM video on the car that became the EV1. Commenting on its technological achievements, John Zwerner, GM Advanced Product Engineering, says "we wanted to drive a stake in the ground.as to what a contemporary produceable electric vehicle would look like and how it would perform if we were to build such a vehicle." Instead, as we know, GM drove a stake in its heart. Literally.

2007 100

Test Drive to Work

Porsche 914 EV Conversion

Since traffic is really light on Sunday morning, I drove to work (15 miles away) and back to see how the 914 would handle. Shifting was a real pain on city streets since the electric motor changes RPM very quickly during acceleration or regeneration. The RPM stays constant when I "coast" unlike a gasoline engine which tends to slowly drift back to "idle." This makes synchronization of the gears rather difficult. As expected, power was rather lacking on the freeway.

2007 100

My First EV Video

Porsche 914 EV Conversion

My friend Pete dropped by for lunch today with his video camera and we captured a four-minute video of the electric car in action as well as a description of the various parts. This is rather unrefined, so enjoy

2007 100

Hacking the Regen System and Fixing Acceleration

Porsche 914 EV Conversion

Well, today was a good day. I got word back from Azure Dynamics after they analyzed my acceleration logs and they pointed me to the EE2NoAccelBat variable. Mine was set to 136 volts. It turns out that if the voltage coming from my batteries fell into the 136 to 149 volt range (EE2NoAccelBat + EE2AccelRamp = 149), then the controller would linearly limit the power going into the motor down to zero when the voltage reached 136.

2007 100