Lithium BugE

Lithium BugE by Nap Pepin
	Range - 200km/125 miles Max. Speed - 130kmh/80mph 0 to 60mph - <7seconds Motor - 3 Phase, 38hp, 86ft-lbs Controller - Curtis 1236 Batteries - LiFePO4 Energy - 7.2kwh, 56wh/mile Equivalent MPG - 628mpg For the latest updates, click here. ---------------------------------------------------------------------------------------------- The Lithium BugE is For Sale! I am accepting offers to purchase the Lithium BugE. Buyer is responsible for arranging shipping and for determining admissibility requirements if importing into the USA or anywhere else. Please send your offer or questions to; nap@nappepin.com ---------------------------------------------------------------------------------------------- Note - The web site address depicted on the Lithium BugE is incorrect and should be www.BugEv.net. I took the pictures immediately after applying the vinyl letters and still need to take new photos since correcting the web address.
	Short Test Drive Video Battery Management System Video
	The Lithium BugE is my first electric vehicle (EV) project. Like many other people, I have always found electric vehicle technology fascinating and as such, I have paid close attention to the developments over the past couple of decades. The two greatest obstacles that kept EVs from entering the market were inadequate battery technology and low oil prices. It has only been until recently that the development and availability of lithium batteries coupled with the dramatic rise in oil prices appear to have created a tipping point, making mass market, pure EVs seemingly viable. Virtually every major automobile manufacturer is developing either pure EVs or extended range plug-in hybrids with promises of availability around 2010 to 2012. In mid 2007, I came to the realization that now was the time to embark on my first EV project. The development and subsequent availability of high energy batteries convinced me I could build my own relatively high-tech electric vehicle and do so at a reasonable cost. My key objective was to build and EV with a 100 mile range. This is not a trivial accomplishment, especially for my first EV project. I have come across few vehicles that can do that and those that can were quite often built by companies or sponsored by major corporations. For my first project, I did not want to incur the costs and risks with building a large vehicle. By large, I really mean small to midsize car compared to a scooter or something like that. The larger the vehicle, the more batteries are required. Costs and risks go up almost proportionally. This first project was intended to provide all of the learning and experiences I would need to build a fully practical vehicle. As well, I did not want to build a vehicle from the ground up unless I had to. Instead, I wanted to focus on the drive system, the electronics and the software needed to run the vehicle and manage the batteries. I cannot recall exactly how I came across the BugE. I must have been searching for electric vehicles on the internet. The BugE is an electric vehicle kit that is manufactured and sold by Blue Sky Design. The basic kit includes a frame, faring, acrylic canopy, seat, motor cover and tires. Everything else must be purchased separately or built. If the vehicle is built as per the manual, the vehicle will travel 30 miles at 30mph using a DC motor, controller and 4 lead acid batteries. The total vehicle cost for a stock BugE is around $6000. I found the BugE intriguing because of the futuristic design, light weight and the simplicity of the vehicle overall. The cost seemed reasonable to me and I was sure I could beat the performance of the stock vehicle. My BugE would be a prototype since I would deviate substantially from the original design. Canada has very strict laws regarding the importation of vehicles. Many of the vehicles that are allowed on the roads in the USA cannot be brought into Canada. Kit vehicles of any type are non-admissible. Over the coarse of several weeks, I did my research and determined that kit vehicles are non admissible if Border Services determines that the collection of parts would resemble the finished vehicle. What I deduced was that anyone can import a collection of parts and accessories from several sources for the purpose of building a homebuilt vehicle. Bringing the parts in from a single source or all in one shipment puts you at risk of Border Services deeming the shipment as non-admissible. Another important point is that no part can have a VIN number it where that part is from a production vehicle that is not allowed in Canada. There are other restrictions around parts too. Convinced there was a way, I purchased the BugE parts under 4 invoices of which the frame was purchased by a friend. I then had the shipments brought in over the course of 3 weeks. This actually only represented about $3000 of my costs. Another $9,000 in costs were for purchasing parts such as the drive components and batteries from other sources. The BugE is marginally a kit at best because there are so many other parts to buy and build. My process for importing what I did was allowed and was perfectly legal. Later, (after I built the vehicle) when it was time to request a VIN number, I contacted The Insurance Bureau of Canada who sent an investigator to my home. Their job is to ensure the vehicle is not made of stolen parts or from parts that have VIN numbers on them that are not allowed in Canada. They were completely satisfied that the vehicle qualified as a home built vehicle having seen the work I had to do and subsequently assigned me a VIN number and plate. My Lithium BugE was now a legal vehicle in Canada.
		Uncrated, this is what the BugE looks like. The package includes all the fiberglass parts including the faring, battery box and cover, the acrylic canopy. Sorry, no larger photo is available.
	During the time that the shipments were in transport, I focused my time on finding the best batteries, motor and motor controller I could find. I researched the various types of motors trying to understand their operating characteristics and efficiency. I studied performance curves and operating data for DC shunt motors, Sepex, Permanent Magnet (brushed and brushless) and AC induction motors. After the study was complete, I searched for what was readily available and appropriately sized for my application. Without getting into a lot of detail, I believe I chose the best motor for this application. I chose an aftermarket high performance AC motor designed for golf cars. At 48 volts, the motor operates at about 90% efficiency, puts out up to 38hp and exhibits a torque of 86 ft-lbs. This was already a big performance leap over the Advanced DC motor that is used in a stock BugE build. I spoke to the manufacturer of the Advanced DC series wound 140-01-4005 motor used in the stock BugE. They stated that their motor would be operating in the low 70s for efficiency given the way it is used in the stock BugE. Paired with the AC motor that I bought was a powerful and efficient Curtis controller (Model 1236). This AC controller supports variable regenerative braking, includes lots of performance parameters that can be tuned and it supports Vehicle Control Language (VCL). VCL could allow me to program the controller to run my gauges, turn on the brake light when in regenerative braking, etc.. The controller allows battery voltages as high as 105 volts meaning I could build a battery pack with a much higher voltage than 48 volts as in the stock BugE. Doing this would result in the motor operating above 90% efficiency as well as fewer losses across much of my motor, controller and battery charger wiring. As well, I would benefit from being able to use smaller conductors and therefore reduced weight. The motor was however 10 lbs heavier than the stock DC motor and would require a completely different motor mount than the one that is pre-welded to the BugE frame.
	This Curtis 1236 AC controller is rated for 105 volts at 300 amps. It supports Vehicle Control Language programming. There are a total of 16 inputs and outputs. Its base operating system allows for dozens of performance parameters to be tuned and customized. I purchased the motor and controller from Thunderstruck EV in the USA. They pre-built a basic wiring harness for me.
	My research into suitable batteries was equally as daunting of a task. I built numerous spreadsheets that helped me evaluate various battery chemistries, form factors, power density, cost per cycle, etc.. Lithium was clearly the front runner for performance but what I found on the market was batteries that were very costly. Given that, I Initially decided that a sub C commercial grade nickel metal hydride battery was my best choice for performance vs cost. Restricted by the maximum weight I could allow for, it appeared I would have to settle for about an 80 mile range. I was very close to purchasing about $3300 worth of the nickel metal hydride batteries when I finally learned about the availability of high capacity lithium iron phosphate batteries. I had read about a fellow named Peter Perkins in the UK who built his "Solar Van" using Thunder Sky lithium cobalt batteries. His van didn't actually run on solar energy, it was one of his various charging sources. Peter did an impressive job in the construction of his van and was happy to give me advice whenever I had questions. I ultimately found the Thunder Sky website and began to study their products which include various lithium batteries types and form factors. I was shocked to see how cost effective these batteries actually were and how new lithium iron phosphate batteries were a huge improvement over the lithium cobalt batteries. Lithium cobalt batteries were the batteries that were known to ignite and considered a dangerous good. They were typically rated for up to 200 deep cycles (full charge and full discharge) and cost about $10.00 per amp-hour (ah) just a few years ago. Two to three years later and we have lithium iron phosphate (LiFePO4) batteries that are safe, rated for 2000 to 3000 cycles and cost only $2.00 per ah. When you work out the life cycle costs, the LiFePO4 batteries are 50 to 75 times more cost effective than that their predecessor, the lithium cobalt type. Other improvements include huge improvements in thermal properties, a simpler charging process and far less risk of damage during the charging process.
		The Thunder Sky LiFePo4 batteries are probably the best battery vs cost currently on the market. There are some better performers such as the A123 systems batteries rated for 7000 cycles but they are very expensive and almost impossible to obtain. To see the entire data sheet for my batteries, click here.
	Thunderstruck EV was superb in helping me obtain the Thunder Sky batteries amongst other things. Before I ordered the batteries, I needed to determine the size and amount of cells I needed to ensure a 100 mile range. I built a number of spreadsheets that allowed me to factor in things like vehicle weight, motor and controller efficiency, the effects of regenerative braking and even fudge factors such as the effect on battery capacity at various discharge rates. My calculations were however entirely reliant on Blue Sky Design's stock BugE performance specifications. The stock BugE uses 4 Optima Blue Top marine batteries rated at 55 ah per cell. According to Blue Sky Design, the BugE will travel 30 miles at 30 mph. What I needed to do was to determine the amount of usable energy in the Optima lead acid batteries and then calculate the amount of energy I would need after factoring the efficiency gains I had made using the AC motor, the gains with regenerative braking, etc.. Ultimately I determined that I needed about 7kwh of energy for my BugE to travel 100 miles or more. When I considered the maximum voltage that the Curtis motor controller allows (105 volts), this meant I could have no more than 24 cells. For the sake of the controller, my voltage calculation had to be based on the peak charging voltage of the batteries (4.25 Volts) My peak battery voltage was therefore 24 X 4.25 = 102 volts. Next I determined that my average operating current would affect each cells nominal voltage. Since my BugE would be operating at more than twice the voltage as the stock BugE, my operating current would be about 1/2 or a little less that of the stock BugE at 30mph. This worked out to about 20 to 30 Amps. Therefore my cells should exhibit an operating voltage in and around the discharge curve shown for 0.3 C as per the graph below. From the graph, I deduced a nominal cell voltage of 3.35 volts, not 3.2 volts as most people do. An important phenomena is depicted in the graph below in that at lower discharge rates, not only is the nominal cell voltage higher, the capacity of the battery is higher too. This results in higher usable energy because energy is determine by volts X ah. If I used 3.2 volts as a nominal cell voltage and 90ah as the cell capacity, the theoretical amount of usable energy is 288 watt-hours or 6.9kwh for 24 cells. However when I assume 3.35 volts for the nominal cell voltage and say 93 ah for the cell capacity, I get 308 watt-hours per cell or 7.48kwh for all 24 cells.

	The discharge curves of the Thunder Sky batteries show a higher nominal voltage and capacity at lower discharge currents. This is typical of most battery types. This becomes important when determining the energy that is available.
	Ultimately, I determined that the TSLFP90 (90 ah) was the best cell for my application. Unfortunately the 24 cells would not fit into the stock BugE battery box. Only 17 could be stored there. I would have to construct an additional battery box which would hold the other 7 cells . I then ordered the batteries, the motor and motor controller, all from Thunderstruck EV. I was now committed to whatever performance those critical parts would deliver.
	The BugE body kit is shown here with some of the parts including the faring, acrylic canopy, seat, motor cover and tires. Building a stock BugE takes an average of 60 hours. My prototype will take much longer.
	Next