Specifications

Vehicle:

Sensei EV, a 1995 Kawasaki EX250 Ninja 250, converted to electric power.

Motor:

Mars ME0709 - Permanent Magnet DC Often called "Etek-RT" because it was designed as a higher torque replacement for the discontinued Briggs & Stratton Etek. The ME0709 was made by Mars, which has changed its name to Motoenergy. Someone at ElMoto put together a group order with EV Drives and I got a great deal.

Controller:

Kelly KD72401 - Kelly brushed DC motor controller. This is what controls the motor's speed. Based on input from a Magura electric throttle on the handlbars, the controller pulses the power delivered to the motor, creating higher or lower average voltage. This controller is significantly beefier than I need (rated to 400 amps, and I rarely pull over 100 amps). It includes regenerative braking to allow the motor to act as a generator, slowing the bike while recharging the batteries. As far more power is used to keep the motorcycle moving than just accellerate it, this would not be a huge range booster, so I haven't been in a rush to set it up.

Batteries:

24 SE40AHA, 3.30 Volt, Lithium Iron Phosphate CALB (formerly known as Sky Energy) 40Ah cells. Pack is actually about 82v fresh off the charger. Purchased from Lithium Storage. CALB opened a US warehouse and distribution center in 2011, greatly reducing delivery time.

Battery Manager:

Mini BMS. This is the least expensive lithium battery management system for this type of application that provides cell level overcharge (HVC) and over-discharge (LVC) protection as well as charge shunting for battery balancing. Dimitri, the system's designer has been very open about how his system works, and the failsafe philosophy behind its design (opto-isolation of battery current from cell/master communication loop, shunts failing to "off" mode if a component burns out, etc.). He is also quite easily accessible for support and troubleshooting. This product is also made in the USA - a rare thing for EV components.

System Voltage:

79 Volts - Fresh off the charger, the battery pack is at 82v. By the wonders of EV nomenclature, this is typically referred to as a 72-volt system, as that would be the nominal voltage with 6 12-volt lead acid batteries.

Charger:

TSL72-15 - Looks like it's made by Sky Energy It was purchased from Elite Power Solutions. It has been working reliably, and charges the pack in a couple of hours (or less depending on how far it was ridden). This is my second charger, the first was a 10 amp from Chennic (appears to be a Kelly charger with the Kelly logo cut out of the label) that did not function. For several weeks, Chennic's tech went back and forth with me in e-mail trying to diagnose its problem. After finally clarifying the problem with multiple videos and photos of the internal components, they simply stopped answering my e-mail. Chennic has proven themselves to be unreliable with horrible post sale support.

DC/DC Converter:

Vicor V72C12E150BL - This provides 12v power for the headlight, BMS, Cycle Analyst and LED signal and tail lamps. It is very compact and doesn't even kick off noticeable heat - fantastic!

Instrumentation:

Large Screen, High-Amperage Cycle Analyst - This is a full computer in the dashboard, measuring and computing battery drain, performance and speed. Measuring power consumption is important as it's the best indicator of how much charge is left in the batteries. Lithium batteries don't steadily drop in voltage as they are discharged, until they get down around 80% discharged - the point where we want to stop using them to avoid over-discharge damage. Unlike like lead-acid batteries we can't tell how full they are just by looking at a voltmeter. The Cycle Analyst tracks how many amp-hours of charge has been pulled from the battery. With a pack of 40 amp-hour batteries, stopping each ride around 26 amp hours or earlier discharges the batteries 70% or less per cycle, to maximize battery life.

Top Speed:

55 MPH (88 KPH) - Geared with 12 tooth front, 52 rear. Gearing with a higher ratio would allow for better acceleration with a reduction in top-end speed or vise-versa if decreasing the ratio. The target top speed of 55mph was chosen to maximize acceleration while allowing the speeds needed for local urban commuting (top local surface street speed limit is 45mph). There is no transmission. While a transmission would probably improve low-end acceleration while allowing the same or higher top-end speeds, the added weight, cost, efficiency drop and space requirements were undesirable for this project.

Acceleration:

Good enough to be comfortable in traffic. Runs straight up to 50, then takes about 3 or 4 seconds for that last bit from 50 to 55.

Range:

30 Miles (48 Kilometers) It has not been run to this limits. Range is estimated based on calculation using watt hours per mile drawn at residential street speeds (30mph Max). In practical city riding, I have been limiting range to about 25 miles to avoid over-stressing the batteries.

Efficiency

83 Watt-Hours Per Mile at average speed of 35Mph with normal urban riding. In typical use efficiency ranges from 75Wh/m to 94Wh/m, depending on average speed and how aggressively it is ridden.

Air Conditioning

RiteTemp Athletics Endurance Vest - Not exactly air conditioning but just as good. Ever since I high-sided my XV-750 in 2010, I have only ridden with full pants, leather jacket, leather gloves and full helmet (before that the helmet was always there, but t-shirts were not uncommon). In Florida's heat and humidity thick safety gear can put you at risk when your brain starts getting sluggish from heat stress. With the Performance Vest under my jacket it literally feels like I'm riding in a cold, air conditioned car, despite high-humidity, full sun and temperatures in the 90s. I usually use the endurance vest. With it, I am comfortable (not cold, but not hot either). It lasts over two hours on the road (twice as long as the performance vest) and instead of charging it in a refrigerator, it self-charges just by hanging it in my air conditioned office.