It?s been a long time coming, but my electric Ninja 250 (dubed ?Sensei? by my wife) is nearing completion.
I?m still breaking in the motor, as the brushes wear to shape and improve their contact area performance gets better. I?m running direct drive (transmissions are rare on electric motorcycles as the super-wide power band makes them not as necessary as with internal combustion) geared to give me a top speed of 55 mph and good acceleration. So far, it?s feeling good for around-town riding where the speed limits range from 30 to 45 mph, and that?s what I face on my 13 mile commute to work.
Riding today on roads with limits ranging from 30 to 40 mph, traffic put my average speed at 35mph, and I drew an average of 83 watt/hours per mile, which puts me at 30.8 mile usable range per charge (draining only 80% of the charge out of the battery pack for max life). Higher speed means more power and less range. It?s looking like about 25 miles if my speed is hovering between 45 and 50 most of the ride.
I started with a 1995 Ninja 250 that I picked up for $250 with no title, tracked down the last titled owner through the motor vehicle division of the county tax office and got a new title issued. Despite being decent mechanically, the bike had been fairly neglected, sitting outside with rubber and cloth rotting.
I stripped everything apart to rebuild brakes and clean and paint the frame. With the engine mechanically supporting the structure of the Ninjette?s frame, I decided to reinforce the frame with a couple of gussets. I?m a newbie welder, and while I was comfortable with things like my battery and motor mounts, my neighbor did the frame welding for me. He?s a retired master welder and laid cleaner welds than the Kawasaki factory.
The frame cleaned up and came back together well
I started designing with sealed lead acid batteries in mind, as they are the most affordable.
I delayed the while while going through some job changes, and when I came back to it, the price of lead batteries had risen, and price of Lithium Iron Phosphate batteries come down. Even through the LiFePO4s cost half-again to double, they should last a good 5 times longer, and are about half the weight for similar energy storage.
So I designed, and re-designed component placement and brackets several times over while waiting the months that ticked by from the time I ordered the batteries until they were manufactured, shipped from China and run through customs here in the states.
I haven?t weighed it, but considering the approximate weight of the parts I pulled off, and what I put on, the weight is pretty similar, and balance feels comparable.
My batteries arrived in December, so the bulk of real construction started after that.
I replaced the stock gauges with an on-board computer (Cycle Analyst) that tracks not only speed, but battery voltage and power consumption as well.
I?m running 24 batteries in series for a peak 82 volts when freshly charged. They are 40 amp-hour capacity cells from China Aviation Lithium Battery, rated for over 3,000 charge cycles in normal operation. Each cell is monitored by a MiniBMS battery monitor to prevent over-discharging or over-charging, both of which can damage the cell shortening its life. The BMS boards are visible in this shot of the lower battery box, which holds 14 cells. The remaining cells are up in the frame in the area normally used for the carbs, air box and starting battery. The ME0709 permanent magnet motor is not mounted in this pic, leaving the batteries visible.
I had my first ride under electric power in March.
Here?s the rider?s view
I have cut the bottom out of the gas tank, and welded in brackets that hold the 15 amp charger and its control relay. Riding to 80% discharge is about 2 hours to recharge - shorter distances mean less time. Since there?s no need for the gas-cap anymore, I re-purposed its ring as a frame to hold a lexan window in over my arc reactor, which serves as a charging status indicator
My original choice for a license plate was 0C8H18, but realizing very few people would understand it, I went with something more straightforward.
I?m riding it on a regular basis now, and plan to start using it for my daily commute after getting settled into my new office (the company I work for just moved a couple of weeks ago) and setting up a charging/parking spot.
Through the whole build my wife?s been very supportive of my electric motorcycle obsession, and reasonably so since she was on a team that built an electric car as part of a scholarship competition when she was in high school. The FAQ here at Ninja250.net was a huge help in the teardown and build-up in everything from choosing tires to removing the swing-arm (better explained than the Haynes manual). The crew at ElMoto.net has also provided a wealth of knowledge and been good springboard for ideas.
__________________ Master your environment and you will survive just fine.
Chances favor the prepared mind.
The electric ninja project is obviously more real world like the Zero and Brammo lines. I'm not sure what the purpose of a super fast, expensive, uncomfortable sport bike is other than a halo product that gives a brand some cred. Sorta like concept vehicles - neat ideas but nobody really buys them.
Still waiting for this market to mature. I haven't found anyone that makes one that will do my 60 mile round trip at freeway speeds, is comfortable, is "reasonably" priced.