Focus on Lithium ion batteries
Green MotorSport started researching lithium ion cells several years ago and produced the world's first lithium ion 12V monoblock long before anyone else had a commercial and reliable product. Over the last 5 years we have been looking very closely at the battery industry, seeking the best solution and we can now say that we have found a suitable candidate where cost, quality and energy density are concerned. Green MotorSport has mainly concentrated on drive train production and electric motor fabrication with the objective of becoming cost efficient. Alongside this development, we have been looking very closely at the battery industry and have evaluated different types of batteries, because in order to catalyze the uptake of electric cars one needs a reliable HP laptop battery solution.
Green MotorSport can now offer the very highest quality lithium ion phosphate (LiFePO4) batteries, suitable for high current and high and low voltage automotive applications. We have chosen our cells on the basis of manufacturing quality and reliability in all weather conditions.
There are many different shapes and sizes of lithium ion cells, and many different chemistries on the market, each of which is chosen for its application. In general there are several types of Lithium formats to choose from for electric cars including the cylinder cell and the Prismatic cell
Choosing the correct IBM laptop battery used to be difficult, and one of the reasons why most electric car makers have chosen a high working voltage battery is basically because the early lithium high capacity cells were not very robust at high current loadings. If the cells in the battery pack were put under high current pressure, then the lifespan of the cells would be dramatically reduced. In order to achieve a reasonable power level for electric cars, the automotive companies pushed the pack voltage up into the hundreds of volts in an attempt to reduce the current drawn from the cells and maintain the power needed. By doing this it would lengthen the lifespan of the battery pack as well as reduce the cost and weight of power train cabling in a vehicle. Some automotive companies even claimed to be running at 1000 volts! However, the new lithium phosphate technology today has the ability to cover both high and low voltage applications without becoming problematic. This is made possible by clever cell nano scale chemistry and the design of the anode and the cathode within the cell. Lithium ion phosphate cells in prismatic, foil packet or even cylinder formats now have the capability of delivering high C rates even at very low pack voltages. This means a low voltage power train of 48 volts is much safer to install, but and also supplies high current discharge rates without damage occurring to the cells' internal structure, and thus retaining a very respectable cycle life. Lithium ion phosphate technology is also a safe and reasonably cost effective deep cycle battery alternative to lead acid.
As an all rounder lithium ion phosphate is a solution winner for most deep cycle electric traction applications. Green MotorSport currently runs its demonstration race cars on as little as 60V achieving high speeds and breathtaking 0-60 MPH times.
Overall lithium battery technology as a chemistry will be the most cost competitive solution for another 5 years at least.
Lithium phosphate technology is probably the safest and least hazardous chemistry on the market. Green MotorSport likes using the Prismatic cells because they are easy to make into larger battery packs, they slot together in a robust block and stack like bricks. The cylinder ones also work well but most cells are small and take up unnecessary space as they do not tessellate due to their nature. Foil cells are reasonable and new research evidence shows high energy densities reaching 180 watt hours per Kg or more, but they do require careful assembly and cooling in some cases under heavy loads.
Within the next ten years there may be better sony laptop batteries on the market, but lithium cell technology will maintain its lead position as a high energy density battery solutions for another five years or so. The other fact to consider is availability. Prismatic cells are now available in volume for reasonable prices and boast good results in low working temperatures.
In the next few years, you may see a number of companies that will be delivering dual battery technologies battery packs that can offer a high C rate and also a large energy density. This is made possible by using two types of lithium chemistry technologies together. This may be in the form of high power cells and high energy cells working in tandem with perhaps super capacitors and clever electronics. However lithium ion phosphate for many applications may already meet the energy and power demands without excessive complication or cost.
There will be certain long range applications that can benefit from these dual battery technologies. Lithium ion phosphate also has the ability to charge very rapidly if required. These cells can be rapid charged to 80% of their capacity within 20 minutes using an intelligent charger coupled with a BMS ( battery monitoring system) although there may be reduction in cycle life. Again Prismatic cells weather better with high charge rates without complicated liquid cooling systems that cost space and extra funds. Areas of research currently in focus are how the chemistry can be changed slightly to increase cycle life even under rapid charging conditions. We expect that the lithium cell will only get better as scientists tweak the chemistry. It's worth noting that even now, the technology does a very reasonable job and offers tremendous benefits for all types of electric cars. Another aspect is that battery chargers are getting better as well. These new battery chargers are much more stable and battery monitoring systems are able to keep an eye on each cell more carefully. Dynamic automotive CAN-bus communication systems enable real time monitoring of strings of cells. Monitoring of cells has also become more reliable. Of course, by using high capacity cells, for example 200 AH or 400AH cells instead of hundreds or even thousands of smaller 3 AH cylinder type cells, ( for example in the Tesla Roadster ), prismatic cells featured above make it possible to use less cells and achieve similar capacities. This in turn leads to a more stable battery pack and safer lower pack voltages to achieve even higher energy densities. The new larger cells mean that less cells are required to achieve the desired battery voltage and capacity, less monitoring wires are needed and if there is less to go wrong there is greater reliability.
Visionary car design
As electric cars and the cost of power train technology falls within the grasp of the many, more and more car designers young and old are now looking forward to the electric car future. In 2011 there has been an influx of very exciting fresh new shapes and designs coming out. One of this year's most fascinating designs came out of IED a student project from the car design school as part of the master course in transportation design based in Torino.
Green MotorSport wishes to congratulate the students on this remarkable piece of work seen here at the Geneva Motor show in 2011 and recommends anyone with a passion for racing cars or electric cars in general to contact IED.