Dual Battery Breakthrough Eyes Electric Bus & Truck Fleets

December 2, 2010

GE’s Global Research team announced an EV breakthrough today that can open the door to widespread adoption of electrification for heavy haulers like buses, delivery trucks and other big transports — a sector that has long been slow to embrace EVs due to high battery costs and large battery size.

The hybrid systems research team successfully demonstrated a dual battery system on a zero tailpipe emissions hybrid transit bus. The technology — which has the potential to cut battery costs by 20 percent — pairs a sodium battery with a lithium battery — essentially combining the pick-up that today’s passenger EVs have with the power storage that big industrial batteries offer.

Doubling down: Many of the 843,000 buses registered in the U.S. travel less than 100 miles per day. Making more of them all-electric would dramatically reduce CO2 emissions and fuel use.

Most types of batteries today come with a trade-off between power and energy storage. For example, lithium batteries — which are what you’ll be using in your new EV — provide a lot of power for acceleration, but are not optimized to store energy for driving range. Sodium batteries are on the opposite side of the spectrum. They store large amounts of energy, but are less optimized for power. GE’s dual battery combines the best attributes of both chemistries into a single system.

Lembit Salasoo, Senior Electrical Engineer and GE’s Principal Investigator on the hybrid bus project said that that one big problem is that the energy needs of big haulers can very greatly based on a vehicle’s size and drive cycle.

“The beauty of our dual battery system is that it can be scaled to deliver just the right combination of power and storage,” he said. And that is where the cost savings comes from, as eliminating the need to build one battery allows for options tailored for specific types of vehicles.

As Lembit explains in a post on the Global Research blog today, “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.”

Charged up: Salasoo is seen here with GE’s ecomagination hybrid locomotive. GE Global Research is the company’s central technology development arm. Its Hybrid Systems Team is a diverse group of some 25 scientists and engineers — a few with more than three decades of experience in electric and hybrid vehicle technologies.

The research is being done as part of a $13 million project with the Federal Transit Administration and the National Fuel Cell Bus Program.

It’s part of a growing hybrid and electric technology portfolio at GE which includes a new battery factory being built in upstate New York; new WattStation EV chargers; and smart-charging partnerships with Nissan and Better Place. GE also announced it would buy 25,000 electric vehicles by 2015 for use in its own fleet and for its fleet customers.

* Read today’s announcement
* Take a look at GE’s other EV research over the years
* Read “The Top 10 Signs EVs Have Gone Mainstream”
* See our infographic on the 10 Best Cities for Electric Vehicles
* See a video clip of the bus in action


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  • Robert Iasillo

    I have wondered for sometime why large scale capacitors are not used in conjunction with batterys for EV’s. The Power side, current flow rate out & back in (regen-braking) to be in part handled with a capacitor, and for contiunous use, the battery provides the electrons (storage). This is the first time I have seen an artical discuss this type concept, but in this case with 2 diff batt teck. Would going to 3 layers, capacitors, Li & Na batteries (each with differnet rate & storage ablitys) provide a better trade off between energy use / size & cost? Or would it just change the life curve on the batteries and not the size & capital cost.

  • Wayne Deyoe

    This is a great advancement and can only make me proud to be part of GE. Keep up the good work.

  • Lembit Salasoo

    Robert:
    we are indeed using a special type of large-scale capacitor, the Ultracapacitor, in SOME of our vehicle projects, and the roof-top enclosure on our bus picture houses a set used in a previous project. The selection of how many different energy storage systems to use, and which specific technologies comes down to a tradeoff of size, cost, life and complexity that is different for every class of vehicle and application.

  • Bill DeFalco

    Taking if from Double Down to Playing 4 ACES. Here’s a suggestion to Greatly Extend Range at Reasonable Cost. Located at several key strategic stops along the route are overhead electrical pickup points – which only span the length of each stop. At these particular stops an arm automatically extends up from the top of the bus to engage the power pickup. Power is then directed to a sealed high efficiency flywheel and motor-generator unit. The flywheel is then rapidly spun up to a very high rpm. As the bus leaves the stop – energy from the flywheel unit is used to assist the heaviest power demand – getting the bus moving again from a dead stop. This will take a considerable load off the batteries, greatly extending their range. Also – Re-Gen breaking energy can be more efficiently captured in the flywheel unit, along with the batteries. The addition of a High Efficiency Capacitive Storage Module would further compliment the electrical storage capacity and further extend the operating range. Even without the overhead power pickups – the flywheel unit and Capacitive Storage unit are more efficient in capturing braking Re-gen energy and these items alone will significantly increase the driving range.

  • deepak

    That is great. But how long will it take before this kind of achievements are actually used for every day purpose ?

  • Joel Melito

    I support Bill DeFalco’s comments regarding means of boosting service range. Many well-built transit system stops include overhead weather protection, an ideal location for a catenary-style pickup; but, I would give preference to inductive pickup design over straight electrical pickup as the separation at “take-off” might have a significant stray arc risk. Urban electric distribution typically operates in voltage ranges of 7200/12470Y, 7620/13200Y, 14400/24940Y, and 19920/34500Y according to a quick Google search, and should offer plenty of inductive power. I attended university and worked afterward in Philadelphia, givng me the opportunity to ride both the tracked and trackless (converted busses) trollies. You don’t forget the peculiar scraping sound of an arcing catenary. Flywheels or ultracapacitors is best left to the design development team to decide. However, what I find really matters to battery driven vehicles is the vehicle-to-payload mass ratio. Electric vehicles have to address the same design problem as aircraft and rockets – a heavy vehicle consumes most of the”fuel” and electric vehicles are doubly penalized because they don’t get lighter as they consume their fuel. Again, a quick Google search indicates a transit bus weighs about 12 tons whereas 40 passengers weighing an average of 200 pounds and carrying 15 pounds of goods each weigh a total of 4.3 tons; a lousy 3/4ths of the total transit mass is the vehicle. Focus on getting the vehicle-to-payload mass ratio down to 1:1 and service range wont be a problem with the existing storage and drive system technology.