Lithium-ion battery pack for 2014 Chevrolet Spark EV electric carEnlarge Photo
Electronic sensors don't occupy a huge amount of space in electric car battery packs, but conversely, making sensors smaller could make the packs themselves much more compact.
According to the MIT Technology Review, the U.S. government’s Advanced Research Projects Agency for Energy (ARPA-E) says smaller sensors monitoring individual cells in a battery pack could reduce pack size by 20-30 percent.
It's all about monitoring. Tiny sensors could be used to assess the state of every cell, relaying more detailed data to the car's control systems. As a result of this, automakers could safely store more energy in the batteries, rather than building in the high margins for voltage or charging ability they do with existing packs.
Greater energy density means smaller battery packs can be used for the same capacity--or alternatively, a battery the same size of existing packs could offer ever greater range.
The research came about with a simple question, says Ilan Gur, a program manager at ARPA-E. "What if we remove those blinders? How much more could you get out of a battery system if you actually knew what was happening inside the cells?"
Fiber optic battery sensors remove that large slice of the unknown. They aren't electrically conductive, so can be embedded within cells without affecting the battery's performance. By monitoring temperature, chemical composition, mechanical strain, voltages at each electrode, batteries could be run much closer to their limits with safety. Cost wouldn't increase much either--around five percent, and that would be offset by being able to make the packs smaller.
Other technology ARPA-E is exploring includes a way of heating and cooling battery cells from within, maintaining optimal temperature and extending each cell's life. Ford is also developing tech alongside ARPA-E--a battery tester to detect unwanted chemical changes in the battery.
As the Review explains, some still have doubts all these improvements will have the desired 20-30 percent size reduction--GM battery engineering director Bill Wallace says it's "a big leap"--small improvements in existing technology could still be the most cost-effective way of driving down prices and improving the technology until bigger steps are taken.
[Hat tip: Nikki Gordon-Bloomfield]