Researchers seek longer battery life for electric locomotive

Jan 04, 2013
Researchers seek longer battery life for electric locomotive
Norfolk Southern operates 21,000 route-miles in 22 states. Credit: Michael Bezilla

(Phys.org)—Norfolk Southern Railway No. 999 is the first all-electric, battery-powered locomotive in the United States. But when one of the thousand lead-acid batteries that power it dies, the locomotive shuts down. To combat this problem, a team of Penn State researchers is developing more cost-effective ways to prolong battery life.

The experimental locomotive's batteries, just like automotive batteries, are rechargeable until they eventually die. A leading cause of damage and death in lead-acid batteries is sulfation, a degradation of the battery caused by frequent charging and discharging that creates an accumulation of lead sulfate.

In a recent study, the researchers looked for ways to improve regular practices. The methods had to be nondestructive, simple and cheap—using as few , electronics and supporting hardware as possible while still remaining effective at identifying and decreasing sulfation.

"We wanted to reverse the sulfation to rejuvenate the battery and bring it back to life," said Christopher Rahn, professor of mechanical engineering.

Rahn, along with mechanical engineering research assistants Ying Shi and Christopher Ferone, cycled a lead-acid battery for three months in the same way it would be used in a locomotive. They used a process called electroimpedance and full charge/discharge to identify the main aging mechanisms. Through this, the researchers identified sulfation in one of the six . They then designed a charging that could charge the battery and reduce sulfation, but was also able to stop charging before other forms of degradation occurred. The algorithm successfully revived the dead cell and increased the overall capacity. The researchers, who report their results in the current issue of the , then compared the battery to a new battery.

"We desulfated it, and we increased its capacity," said Rahn. "We didn't increase it all the way to brand new. We weren't able to do that, but we did get a big boost."

The researchers increased the cell capacity by 41 percent and the overall battery capacity by 30 percent. Even better results might have occurred if sulfation were the only aging mechanism at play, but the researchers found other factors reduced capacity, as well.

"Some of the other cells we identified may have had a water loss issue," said Rahn. "And for these types of batteries, there's nothing you can do about it."

Other mechanisms that can damage lead-acid batteries include positive electrode corrosion, irreversible hard sulfation, positive electrode softening or shedding, electrolyte stratification, internal short-circuiting and mechanical damage.

The researchers are now developing alternative models to replace the electroimpedance spectroscopy model that would allow charging right up to, but not past, sulfation in batteries where sulfation is not yet present, hoping to prevent it from occurring in the first place.

"You would charge as fast as you can and right when you see gassing starting to happen, you ramp down and reduce the current charging," said Rahn. "It's still related to degradation, but it's not really a rejuvenation project anymore."

Penn State and Norfolk Southern, which operates 21,000 route-miles in 22 states, began developing No. 999 in 2008 to evaluate the application of battery technologies for railroad motive power, with particular interest in energy savings and emissions reduction.

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User comments : 11

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Shootist
2 / 5 (9) Jan 04, 2013
Researchers seek longer battery life for electric locomotive


Stupid is,
as stupid does.

Third rail or semaphore. Batteries are for ipads.
tekram
not rated yet Jan 04, 2013
140,000 miles of railroad tracks in the US. Diesel-electric and now hybrid locomotives are cheaper to run. You work with what you got.
antialias_physorg
5 / 5 (1) Jan 04, 2013
If it's just a change in charging strategy this could also translate into longer battery life in your car.
Don't forget that lead acid batteries are used in many places.
Lurker2358
2 / 5 (2) Jan 04, 2013
Third rail or semaphore. Batteries are for ipads.


It's America.

We must waste resources as efficiently as possible.
packrat
1 / 5 (1) Jan 04, 2013
I wonder why they didn't use reverse voltage pingers on the batteries. That works well for prolonging the life of lead acid batteries and making old ones useful again by removing the sulfates. Used at the same time as a good 3 stage charger will give about as much life to them as they can get as long at mechanical damage isn't the problem. The article doesn't say anything about how low a discharge they are taken to in normal use either. That makes a big difference in the hard sulfate accumulations. Take them below 30 percent a few times and it ruins lead acid batteries quickly. Not much you can really do once that happens as the pingers don't really work at that point either very well.
javjav
2.5 / 5 (2) Jan 04, 2013
In sunny areas, they could add solar panels to this train. Not only on the roof but specially by adding a lot of lightweight solar wagons dedicated to bring additional panels. The direct use of solar electricity locally is efficient, and they could still charge the batteries at the times where no thrust is needed. No need for grid, no need for infrastructure costs to adapt the railways, and in many tracks there are kilometers of available space behind the train for adding solar wagons to it.
Newbeak
not rated yet Jan 04, 2013
Why not Solar Roadways applied to rail beds? See:http://en.wikiped..._roadway
Jimee
not rated yet Jan 04, 2013
Interesting to see if solar panels could hold up to use on a railroad car, and whether you could carry enough panels to effectively assist in charging those huge batteries.
Newbeak
not rated yet Jan 05, 2013
Interesting to see if solar panels could hold up to use on a railroad car, and whether you could carry enough panels to effectively assist in charging those huge batteries.

You could never install enough panels on a train to power more than accessories.But putting panels on a railbed between rails is a different kettle of fish.How many thousands of miles of track are there in the U.S.?
baudrunner
1 / 5 (2) Jan 05, 2013
A thousand lead-acid batteries? What is needed is an entirely new lead-acid design that allows for routine wholesale maintenance operations like a rotating assembly of plates that undergo regular cleansing and purification cycles. This is a freight locomotive, right, not a car?
EdmundC
not rated yet Jan 05, 2013
Or you could use 864 Axion Power PbC lead-carbon batteries which have very high charge acceptance and many times the cycle life. Sulfation is no longer an issue. I understand that Penn State has been contracted by Norfolk southern to test these batteries.
The NS999 is a switcher and stays in the yard. But NSC is also interested in developing an over-the-rail (OTR) hybrid for use over rail lines where elevation changes would allow the batteries to assist on inclines and charge via regenerative braking on the declines.