Eric Tischer's VW Passat EV Conversion

90,524 miles without gas since 4/18/2009

Laguna Seca Refuel Event 2013-06-30


Video overview of all the modifications I made to make my Passat electric.
Overview of all the modifications I made to make my Passat electric.


Video overview of the drive inverter I built


After 7 years, and over 75,000 miles I finally had my first breakdown. The fault signal from the IGBT module was indicating a fault. I replaced the IGBT module and was back on the road in about 90 minutes.


SolarCity just finished the installation of our solar panels. They certainly exceeded my expectations. The panels, inverter and all wiring was completed in one day by a team of 4 guys at SolarCity.

Our 3.6kw system should produce 5,060kwhr each year. In terms of EV mileage it's about 12,500 miles per year, about twice what I actually use since I charge at work 50% of the time.

Since SolarCity was already upgrading my electrical panel, I requested a quote to upgrade my service from 100A to 200A. I told them my goal was to install a 50A EV charging outlet, or 100A Telsa charger. They installed a supersized 200A panel, took care of permitting and PG&E hookup, all free of charge.
As part of the permitting process, the city inspector needs to make sure the house has a carbon monoxide detector, SolarCity installed one free of charge.

Upgraded 200A service
for EV charging

SolarCity performing their
home energy audit.

SolarCity performed an energy audit on my house. This involved sealing off the heater vents and pressurizing the house to measure how much air leaks out. They checked the attic, crawl space, and sealing around pipes and wires in the walls. They checked the furnace, A/C, water heater, and all appliances for energy efficiency. There was team of 3 people inspecting the house for about 3 hours, and they provided comprehensive report on where money would be best spent improving efficiency. This was included in the cost of our solar system.


We decided to add solar panels to our house, we purchased a 3.6kw system for $9,014 from SolarCity. That's just $2.50 per watt including the inverter, permitting, city inspections, and installation.

Last month (August) we used 1,006Kw/hr. 57% of that usage was between midnight and 7am when electricity is cheapest, and 25% of that usage was at the 54 cent rate!

Base Usage 5th Tier Usage
Day Rate 30.0 Cents 54.0 Cents (PG&E)
(9.3 Cents SolarCity)
Night Rate 3.7 Cents
(EV charging)
19.0 Cents

The goal is to buy power from PG&E when it is cheap, and sell it back when it is most expensive. Power from SolarCity costs us 9.337 Cents/kWhr, we prepaid 20 years of electricity (96,541 kWhr) for $9014. I chose a solar system that covers 50% of our usage. Covering 50% of our usage, drops us down into our baseline usage, lowering our bill by 75%. If we were to size the solar system to cover 100% of our usage, it would double the cost of the system, but would only save us an additional 25%, so I think 50% usage is perfect. I still want to buy power from PG&E at the 3.7 cent night rate.


I bought a Tesla Roadster charge port ($250), so in addition to L14-50, L6-20, J1772, and standard 115v outlets, I can now charge at Tesla charging stations. The Roadster stations are 70A 208-240V.

I made a bracket for my trunk lid, see above pic. It allows me to lock up my charging cables so they can't be stolen or unplugged, it also helps let some of the hot air escape the trunk.


Handy graph from PG&E showing energy usage though out the day. I charge my car from midnight to 6am, this is about 50 miles of driving. We certainly use the majority of our power at night during off peak hours. Looks like I was using 20kwh to charge, so about 400whr/mile. My linkpro shows I get about 330whr/mile, so my charge efficiency is about 82%.

We are on the E9 rate which makes electricity cheaper at night and pricier during the day. The first tier of usage is very cheap, you can see how the price increase though out the month as we extend into higher tiers.


I added a huge blower fan for cooling the trunk while charging. This should exchange the air in the trunk twice every minute (123 CFM).

Fresh air is sucked in though the existing trunk vent, then cool air is blown past my DC-DC converter and charger. The blower fan does double duty while I'm driving by cooling the A/C compressor's inverter.


Getting the Passat tach working has been a bit of a challenge. The needle movement is done with a stepper motor. I bought an Arduino and a stepper motor card to drive the stepper motor. I had just enough I/O left on the Ardunio to run an LCD display.

The LCD displays pack voltage, and the lowest voltage reading (sag) over the last 30 seconds.


Air Conditioning install is complete! Check out the A/C link on the left for the full details.


Considering I removed the engine wiring and ECU, I never have much hope of having a working speedometer. Thanks to a random email from an Aussie who is also converting his 2001 VW, my speedo and odometer are working! Check out the awesome MPGs.

I started my new job at Tesla motors! I'm now putting 85 miles a day on the Passat!

Encoder kit for the Ford Siemens motor

I'm finally adding an encoder to my motor. The motors built in encoder was only 64 lines, and this was too low for my inverter to read. The encoder will provide accurate speed feedback at low RPMs, which should improve off the line torque.

The kit consists of an expanding coupling which is inserted into the hollow shaft of the motor. The encoder mount slides into the bearing journal of the rear cover. A signal conditioner converts the encoders single ended output to differential outputs for long cable runs.

My encoder setup doesn't use bearings so it won't restrict the max rpm of motor. The encoder disc is 250 lines.

Fill'er up!

Solyndra installs EV charging stations. I can charge at 5.5 miles per hour at work, and up to 12 miles per hour at home (using 230v). This means, after driving 24 miles, I can recharge in 2 hours. I recently made a J1772 adapter so I can charge at 208V from public charging stations.

New Top speed: 105 mph

Top speed was tested on flat ground in 5th gear.
Current from the battery was 216 amps, or roughly 90 hp. The cooling upgrade to my inverter was the biggest factor associated with increasing top speed.

My hill climbing top speed is up too. I can maintain 75mph climbing a 6% grade (south bound Sunol grade in Sunol, California). Current from the battery was 235A.

"Fuel" gauge

Today I added a LinkPro battery monitor (equivalent to a gas gauge).
The LinkPro calculates Amp-hours and "% full", letting me know how much charge is left in my battery pack.

1 amp hour lets me drive about 1.2 miles. My battery is 100 amp hours, so I should have 100 mile range with some reserve capacity.

The LinkPro also displays Amps, this lets me know how quickly I'm draining my batteries (or how long it will take till they are fully charged if I am charging). There is more info about the LinkPro in the charger section.

Battery Management installed


I spent about 30 hours installing BMS on my car over the weekend. I added a new Battery Management link in the navigation window.

The cells located under the car (where the gas tank used to be), behind the seat, and in the spare tire well, were impossible to access. I installed some din-rail mounted fuse holders in an easy to access location, now I can monitor and balance the cells remotely. The cell wiring is protected with 3 amp fuses (purple).

I made some plastic spacers so the BMS boards could be rigidly stacked.



I upgraded the heat sink in my inverter to a six row chill plate. The IGBT pack is now mounting directly to the copper cooling lines for maximum heat transfer. My homebuilt inverter now has triple the cooling power, and runs about 50 degrees F cooler!


2010-09-11 Here are some of the minor improvements I've made over the last six months.

I discovered the 2002 model Passats have a rain cover, but my 2001 Passat doesn't. I bought the parts and installed the cover. This really cleans things up!

I built a shelf above my batteries, this is where my BMS will be mounted.

My battery charger exhausts quite a bit of hot air, and since the charger is sealed in the trunk, this heat has no where to escape. I added some blowers just above the chargers exhaust. They suck the hot air, and blow it out of the trunk though a hole behind the rear license plate.

The fans are thermostatically controlled so they typically only run on hot days. They are also powered from a small power supply which is powered by 115vac or 230vac from the charging plug. This supply also energizes an interlock relay which prevents me from driving with the charging cord plugged in.


2010-05-29 I made some major improvements to the inverter and knocked two seconds off my 0-60 time!

Here is a graph showing 0-60 in 14 seconds (6800rpm) only using 2nd gear.

DC Bus Voltage (0-400 VDC)
(The DC voltage sag is indicative of battery current, every 10v sag = 100A).

Motor RPM x 20 (0-8000 RPM)
Motor current (0-400 Amps/Phase)

I find myself driving 75-80mph on my commute home now! There is much less traffic since NUMMI has closed. At 100A, the car maintains 78mph, compare this to 60 amps at 60mph. My range at 60mph should be 100 miles. At 78mph it looks like my range gets reduced to about 75 miles.

I got a $2400 tax credit which covers 10% of the cost of converting the car to electric.

My insurance company required me to get an appraisal for my car after I told them I just installed a twelve thousand dollar battery pack. Their appraiser estimated the cars value at $52k! At first I was upset I had to deal with the hassle and expense of an appraisal, but if anything ever happened to the car, the appraisers 45 page report clearly shows why it is worth more than blue book.


Got the car officially weighed, it is 3700 lbs.

Charging Station

I wired in a GFI and timer to take advantage of our $0.03/kWhr electricity rate after midnight. Electricity during peak hours is 9x more expensive! Charging from midnight to 7am brings my cost per mile down to 0.5 cents per mile ( I charge at work for free 50% of the time).

Cost to drive 1000 miles in the Electric car = $5
Cost to drive 1000 miles in my Land Rover = $244 (plus oil changes, tune ups, fixing oil leaks...)


I added up 85 invoices, and my total cost in the car is 27,431.36

Big ticket items were:
$1,800 The car itself, 2001 Passat
$1,638 Ford/Siemens motor
$1,450 Painting the roof and new front bumper
$12,334 Thundersky Cells, 99 100Ah
$1,163 Inverter brains
$2,450 Battery charger



My battery shipment was delayed, all in all it took 3.5 months for them to arrive. Since I had nothing better to do with the car, I made some super awesome battery racks. I added a "Battery Upgrade" link to the left window frame.

I also rotated my motor 90 degrees to put the junction box and coolant fittings on the side, this allows the battery rack to sit 2" lower in the car.

Update (car had old lead acid battery pack)


After 41 days of waiting I finally got my carpool stickers!!

It's hard to tell, but I also installed my custom wound rear springs. These springs are designed to support an additional 500lbs, and my car sits perfectly level now.

Update (car had old lead acid battery pack)

Offical weight of my Passat (including driver) is 4200 lbs

Non-official dyno reading of 83.5hp (running daily driver mode, 95% power)


Results from this test were within 1% of the average. The average was made up of 10 runs 0-60 in both directions. There are other torque/current profiles I have created which produce higher hp numbers, but 95% current limit has proven reliable, and that is likely what will be used for production. This is horsepower measured at the wheel, which includes drivetrain losses.



There is an article about my car in Wired magazine.

2009-02-15 First drive around the block.

Video of the week. (6mB)

I got some major bugs worked out of my AC motor controller. The motor is now super smooth and quiet, and my IGBTs aren't overheating anymore! I was even able to take the car around the block. I still have much more work to do (power brakes, power steering, cooling system) but I couldn't resist. I was driving around with a 5 gallon home depot bucket on the roof, this was my cooling system for my IGBT.

2008-07-31 I got my motor to turn!
Video of the week. (4mB)

Then two seconds later, KABOOM! I talked with the IGBT tech support team, the problem appears too much inductance between my dc bus and the IGBT. They recommend using flat plates of copper bus bar instead of wire.

Taking measurements to make Adapter Plate

The transmission and motor were mounted in a CNC. All dowel pins, shaft centerlines, and bolt holes were located using a dial indicator mounted to the spindle head.

My motor

Received my motor today. It's a Siemens liquid cooled 42hp (90hp peak) 3 phase motor. Part No: 1PV5133-4WS20 W11

My 2001 VW Passat

I bought a 2001 VW Passat with a siezed cam on Craigslist for $1800.