Toyota MR2 EV.MR2 EV with new paint job rear viewfront battery compartmentrear battery compartmentMR2 EV with new paint job side viewtrunk batteries.motor and transmission
OwnerBrian Hughes
Owner's Other EV2004 Scion xB
LocationSeattle, Washington United States map
Vehicle1985 Toyota MR2
*** SOLD locally as of August 2013. ***

EV built for maximum practicality- nominal conversion cost ($11500 to get it running), best range possible, decent but not blistering performance, most of the trunk space still available.
MotorAdvanced DC FB-4001 9 Series Wound DC
standard 9" ADC with tail shaft.
DrivetrainModified transmission for reduced friction. Electronic reversing. (No mechanical reverse gear) Lightweight aluminum flywheel without ring gear. Modified and repositioned motor mounts to increase clearance for battery installation.
ControllerCurtis 1231C
500 Amp
Batteries21 Trojan T-105, 6.00 Volt, Lead-Acid, Flooded
7 Batteries up front, 10 in engine compartment, 4 in sunken bay in the trunk, leaving most of the trunk still available for cargo.

I originally designed it for 136v system (seventeen T-875 8v batteries) but these were unavailable when I needed them without 3-month special order, so I ran 102v (17 6 volt T-105s) up until I got the opportunity to buy four more T-105s at a very good price. I installed these in a new sunken battery compartment in the trunk at mile 190678. Top speed improved by 10mph (to 70+mph) and range increased by about 25%)
System Voltage126 Volts
ChargerRussco 24-120 SO
optional footprint charger, with recessed mounting location behind driver's seat, and external boost transformer mounted on chassis.
Heater900W toaster heating element installed into original heater core location. Original blower motor and heat controls operational.
DC/DC Converter Intelipower 9160
Intelipower 9160 RV battery charger designed to run off of 110vac. Maximum output (rated) 60A at 12v, but probably can only make half that running on 126vdc, but good enough. If I were choosing a converter again though I would use one designed for a 120v battery. IMHO This one really is ideal for a 144 - 192v pack, and is not suitable for less than a 120v pack.
InstrumentationAmmeter (on battery) and Voltmeter.
Top Speed70 MPH (112 KPH)
The fastest I have gone with a 126v pack, and plenty fast enough. It might hit 75 if I pushed it.

80mph theoretical top speed (motor RPM limit)
Accelerationwith 126v battery, good under 35mph, and still decent at 60mph. Its not meant to be a drag racer with 1250lbs of batteries on board.

It will probably do 0-60mph (all in 3rd gear) in around 15-20 seconds.
Range55 Miles (88 Kilometers)
Assuming new, healthy batteries. 66 miles achieved at SEVA range rally May 10th, 2008 in Everett, WA. Route included 56 highway miles (55mph) with about 1000 feet of total elevation gain and 10 miles on surface streets once the batteries started getting tired. Freeway route was one loop between exits 199 and 186, and three from exit 186 to 181 on Interstate 5 in Everett, WA. Conditions were dry but with 10mph southernly wind, and 55 degrees farenheit. Traffic was not congested. Carried 2 persons (driver and observer) during the run. Ending SOC was 25% by specific gravity measurement on weakest cell.

Based on my above range rally experience, practical range is at least 55 miles under reasonable driving conditions at highway cruising speeds.

On a hot day, (or if I had battery heaters) it might hit 80 freeway miles!
Watt Hours/Mile200 Wh/Mile
Measured battery-to-wheels.

Observed 190 wh/mile based on 12.6 KWh used, basing measurement on T-105 battery useful capacity of approximately 100Ah at 75A draw and 60 degrees ambient temperature for my battery pack and my 66 mile ev range rally run.

200 wh/mile was my theoretical calculation based on 55mph steady cruise.

I figured it battery-to-wheels (neglecting charging inefficiency) as my major concern is range, not dollars per mile.

The russco charger is probably about 70-80% efficient, so figure 250 - 300Whr/mile at the Kwh meter on the side of the house.
EV Miles
Start:189,335 Miles (304,640 Kilometers)
Current:207,500 Miles (333,867 Kilometers)
Total:18,165 Miles (29,227 Kilometers)
Seating Capacity2 adults

Most of the trunk space is still available for cargo (enough for a golf bag, a large backpack or a week or two's worth of groceries for me).
Curb Weight3,400 Pounds (1,545 Kilograms)
Actual curb weight with 21 Trojan T-105 batteries. No passengers, cargo or gas.

Ratio of battery weight to car weight is 37%
TiresBridgestone B381 low rolling resistance. 185/70R14 on 1991 honda CRX wheels (5" wide 4x100 alloys, the narrowest wheels I could find that fit the car)

44psi tires, but I am running 55psi.
Conversion TimeEstimated 750hrs to get it running.

Considerable chassis modifications to fit batteries is where much of this time went.

Another 25 hours or so to upgrade from 102V traction battery to 126V traction battery.
Conversion Cost$11,500 (including the car itself and repairs to the car not directly relating to conversion.)

Another $400 or so (batteries acquired for about 1/2 retail price) for 126V traction battery upgrade.

Additional FeaturesModified chassis and suspension to carry the battery weight and volume.

Front air dam made from the rear plastic bumper of a Subaru Outback.

Homebuilt computerized battery monitoring system tracking battery amps, kilowatt hours used, and each battery voltage independently and providing graphical display and data logging of this information. Offboard statistical analysis software slowly evolving as well.

Rolling resistance measured at 0.010 on May 9th, 2008. Measurement based on multiple two-direction coast down tests from 40-30mph on a flat concrete roadway, and based on 3400lbs weight and 0.53 CdA. Originally measured at 0.014 but the B381 tires, an alignment job, brake modifications, and 55psi all contributed to reducing RR. RR is where I was shooting for, so any further efficiency improvements that I attempt will focus on CdA.
Sold the car August 2013 after completing my new conversion, a 2004 Scion xB. (See my new evalbum entry)

original website/build log for the car (no longer maintained, but still live) at

I drove the car about 18000 miles total. The first battery pack lasted about 7000 miles and the second battery pack lasted over 10,000 (same brand and configuration as the first). I attribute the difference in longetivity to a better charger. The 2nd battery pack was good for a maximum of 25 miles in warm weather as of when I sold the car and might have a few thousand more miles in it if driven short distances.

The motor, inverter, and DC/DC were 100% reliable for the life of the car. As of when I sold it it needed suspension work (shocks; not suprising considering the weight of the lead acid) and CV joint boots. (which were original) I sold the car with the original russco charger in it, I kept the manzanita for the new car.

New owner was planning to fix the mechanical issues and upgrade to a lithium battery. I wish them the best of luck and hope to see the car around.

code by jerry