Instrument Cluster"Frunk"Engine Compartment (1)Engine Compartment (2)Trunk
OwnerScott Samuel
LocationCorvallis, Oregon United States map
Vehicle1986 Toyota MR2
MotorAdvanced DC FB1-4001-A Series Wound DC
9-inch with auxiliary shaft
DrivetrainOriginal 5-speed manual transmission, clutchless design (through EV America).
ControllerCurtis 1221C
max 400 Amp
Batteries34 CALB/Skyenergy CA100, 3.20 Volt, Lithium Iron Phosphate
100Ah capacity
System Voltage109 Volts
ChargerElcon HF/PFC 1500-96-501
Provides 10.7 Amp @ 110vac. 3.5vdc max per battery (119vdc final total max charge voltage for pack). Can also be used with 220vac. I'm using this in combination with miniBMS from CleanPowerAuto.
HeaterTwo 1KW electric elements in parallel placed in original heater core and A/C enclosures--provide a temperature of 200 deg.F
DC/DC ConverterAstrodyne SD-350D
Provides up to 30 Amp @~14VDC under load; used in combination with auxiliary 12V lawn-tractor battery. I "top-off" charge the tractor battery every day with external 12V charger.
InstrumentationVoltmeters (0-150 VDC; 0-20 VDC), Battery Ammeter (0-500 Amp), Speedometer, Tachometer, EVDisplay (shows SOC,kWh,Ah,fuel level,etc.)
Top Speed73 MPH (117 KPH)
4/22/2013 New top speed with lithium actually untested, but probably similar to original lead-acid speed listed above. I only need to go 55 mph typically and the lithium batteries cost too much to risk damaging them to find new top speed.
AccelerationWith lithium pretty sprightly to 40 mph (even with my conservative choice to keep battery amps below 200 Amps max). Slower thereafter.
Range31 Miles (49 Kilometers)
This is the approximate safe range at a steady 55mph down to 20% SOC. Slower speeds give greater range, e.g. ~70+ miles @ 35mph.
Watt Hours/Mile300 Wh/Mile
This is down from 370+ Whr/Mile @ 55mph for original lead-acid setup.
EV Miles
Start:159,547 Miles (256,711 Kilometers)
Current:177,556 Miles (285,687 Kilometers)
Total:18,009 Miles (28,976 Kilometers)
Seating Capacity2 adults
Curb Weight2,425 Pounds (1,102 Kilograms)
Down from 3,332 for lead-acid setup. Original ICE curb weight was 2,250. Now front/rear weight ratio is 46/54 (almost a perfect 50/50 for best handling).
Tires185/60 R14 LRR
Conversion TimeAbout 3.5 months of actual work.
Conversion CostMore than what I thought it would be, but definitely worth it.
Additional FeaturesI made a tach sensor out of Hall-Effect sensor and 2 south pole magnets from (plus a bit of PVC pipe adapter). Cost less than $35.

All lights interior and exterior are LED, other than headlights. Converted the fog lights to high-intensity LEDs for use as low-current "running lights".

I upgraded the suspension with "Ground-Control" Eibach adjustable spring kit. Vehicle clearance dropped by 1.25-1.5 inches.

I built/shaped my own splash pans out of plastic signboard sheets to protect engine compartment and original radiator area.

12/27/2008 added thermostat to controller heat-sink fan so it only switches on when needed.

1/3/2009 added 2" spring spacers to all suspension springs so ride height is now factory standard.

2/21/2009 mounted DC-DC converter's 0.1 ohm output resistor on a heat-sink-- it was getting so hot it had charred the wooden mounting board!

5/1/2009 increased pack voltage to 108V. (Put a battery box in passenger compartment. No more passenger seat--passenger must sit on floor on a lawn-chair cushion!)

7/1/2009 Installed MR2 GT-style air dam used in later models. Upgraded brake rotors and calipers to larger '89 version. Better braking now, although still not as good as one could want with all the extra battery weight.

4/22/2013 Upgraded to lithium--see below for details.
I bought most of my original lead-acid setup parts from EV America. Lithum parts (batteries, miniBMS, EVDisplay, charger) from Evolve Electrics and CleanPowerAuto.

2/2/2009 I've driven the car for a year now. Only put 94 miles on my ICE car during that period.

3/2/2009 Since November my range has been dropping drastically, down to only about 15-18 miles, with lots of voltage sag. I blamed cold weather, but it continued to be bad even on warmer days. Voltmeter said the batteries were okay, but a specific gravity check via hydrometer finally revealed that one cell of one battery had gone bad and was pulling the whole pack down. I've just replaced that battery and the car "seems" to be back to normal--time will tell.

5/1/2009 to 5/22/2009 Once I worked out how to test the batteries UNDER LOAD (used a 2x4 to hold the accelerator pedal down with car in neutral), I discovered that 5 of the batteries were putting out below-normal volts (4-5 volts). I replaced them and added 2 more to the pack, as well as a battery ammeter. I now try to keep battery current below 200 Amps at all times in hopes of longer battery life--I suspect I fried the 5 batteries by drawing way too much battery amperage too frequently (the new battery ammeter showed that with my old driving style I had been regularly drawing 300 Amps out of the batteries when accelerating and going up hills). Failing to test the batteries under load (they all always read fine under no-load conditions) over the course of the year allowed them to get worse and worse.

1/1/2010 Had to replace 3 more of the original batteries. Their capacity had dropped greatly. Only 7 of original batteries remain after 1 year 10 months. My policy of keeping battery current below 200 amps seems to be protecting the newer batteries installed last spring.

2/28/2013 Almost 18,000 miles now. Batteries are lasting 4 years now that I keep amperage at 100A cruise, 200A hills and acceleration. Of course I can't maintain speed limits going uphill with these limits--only 22 mph max going up steep hills.

4/22/2013 Finished upgrade to 100Ah LiFePo batteries. Maximum recommended continuous battery amperage for long life is "2C", i.e. 200 Amps. Dropped over 900 pounds of weight from original lead-acid setup for same range as before. Trunk is now 75% free for cargo. Only 2 battery packs--one in "frunk," one in engine compartment. Passenger seat re-installed. Car handles MUCH better--quicker acceleration, brakes normally (it's now essentially same weight as ICE version). Going up steep hills I am able to maintain 40-50mph @ 200 battery Amps. Compare this to ~22mph @ 200 battery Amps with lead-acid!

code by jerry