Polaris EATVPolaris EatvPolaris EATVPolaris EATV
OwnerKlaus Wolter
LocationDexter, Michigan United States map
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Vehicle1987 Polaris Trail Boss 250
250cc oil-injected 2-stroke, solid axle, RWD ATV with a torque converter and a Forward-Neutral-Reverse gearbox. It had front drum brakes and a quasi rear disk working through the gearbox.
MotorAdvanced DC A00 4009 Series Wound DC
Drivetrain#50 chain primary from motor to gearbox, the rest was as specified by Polaris. Overall reduction is currently 14 to 1.
ControllerAlltrax AXE4845
400A controller for 24 to 48 VDC
Batteries4 Odyssey PC625, 12.00 Volt, Lead-Acid, AGM
I chose these 12v, ~22AH batteries because they can dish out a lot of current yet are designed for deep-discharge service. LiFePO4 would have been nice but not at 2x the price.
System Voltage48 Volts
ChargerKelly 4815F
Switch-mode 15A charger capable of meeting the 0.4C charge rate recommended by Odyssey.
DC/DC Converter Current Logic 120W DC-DC
Nice unit but NOT isolated. Okay for 48 volts but I would have preferred an isolated unit.
InstrumentationCurtis enGage II battery level meter. Reverse & power ON LED indicators.
Top Speed15 MPH (24 KPH)
Built to pull, not for speed.
RangeNot tested yet.
Watt Hours/MileAgain, not tested.
Seating Capacity2 adults
Curb Weight350 Pounds (159 Kilograms)
Original suspension works well, though it could use some new struts with oil in them.
TiresOriginal 3 psi ATV tires, gentle on the land.
Conversion TimeAbout a year, on and mostly off.
Additional Features5000K, HID arc-lamp in original headlight, mostly as a work light. LED running and taillights, reverse indicator. I use the transmission for reverse.

I used the original thumb throttle and converted it to Hall effect. I designed/built a circuit to give me the 0 to 5 volt as expected by the controller.

I didn't reinstall the plastic body because I like the naked look.
This project was for me to get a my feet wet in EV's. Next up, an electric car. I did a little youtube video: WebPage

code by jerry