An EV battery just the right size and cost for buses
Hi, I am Lembit Salasoo, principal investigator on the FTA Hybrid Transit Bus project. We just reported a big technology milestone on our project, demonstrating a dual battery system on board a transit bus that could be the ideal solution for buses, delivery trucks and other heavy-duty vehicles to go electric. With more than 840,000 buses on the road in the U.S. alone today, just imagine the impact we could have on reducing our carbon footprint with an electrified fleet.
Why a dual battery system, you ask? Many different battery types exist and most come with a trade-off between power and energy storage capacity. For example, lithium batteries deliver high power, but are less optimized to store large amounts of energy. Sodium batteries, however, can store lots of energy, but are less optimized to deliver high power.
Each type of battery, by itself, focuses on one of the two principal needs for electric vehicles – power and driving range. The beauty of our dual system is that it combines the two to address both needs in the most optimal way. A computerized energy management system splits up the vehicle’s power needs between the two batteries with GE’s proprietary technology.
We believe our dual system could address the two principal challenges preventing the more widespread adoption of electric vehicles today – the size and cost of the battery. Unlike a single battery, you wouldn’t have to over-size your single battery to compensate for more storage or power. Additionally, the dual battery can incorporate less expensive battery chemistries into your battery system. According to modeling studies we have done, these attributes could help reduce the cost of your battery by up to 20%.
As you will see from the short video I have included with my blog, the dual battery system works. Right now, our bus has a top speed of 50 mph and about a 60-80 mile range under idealized conditions. The ultimate target is 62 mph and a real-life 100-mile range, while traveling a transit bus route with its multiple stops and starts.
One question you might be thinking is why just buses and big trucks, not cars? Well, we are currently studying the engineering and cost implications for passenger cars. But generally, larger electric vehicle applications such as transit buses and delivery trucks need more energy stored in their traction battery system to drive the required vehicle range and also higher power capability to meet the required acceleration rates. The need for a more balanced energy mix comes into play more than it would with smaller, passenger cars.
Like many EV enthusiasts, I have been excited by all of the recent activity and advancements in electric vehicle and battery technologies. For engineers like me that have been working on these technologies for many years and decades, it is really exciting to see the promise of electric transportation is finally beginning to emerge.
Next up for our team is to install this great technology on a new modern, advanced composites lightweight zero-emissions bus. The bus will have a whole new chassis. With a lightweight platform, we hope to see improved performance in both speed and range. I’ll be sure to provide an update when our next demonstration takes place. In the meantime, you can read the full press release here.
Hello Lembit – can you tell me whether there is any natural graphite used in the fabrication of the lithium battery? I work for a graphite mining company and it would be helpful to know whether your particular lithium battery uses natural graphite. Thanks very much.
Regards,
Paul K. Cooper