#1 cleantech news, reviews, & analysis site in the world. Subscribe today. The future is now.


Batteries

Published on May 16th, 2017 | by James Ayre

0

Vehicle-To-Grid Discharge, Even At Constant Power, Is Detrimental To EV Battery Performance, Study Finds

May 16th, 2017 by  


There have long been critics of the idea of widespread use of electric vehicle (EV) vehicle-to-grid (V2G) technologies for a variety of reasons, but largely in relation to the potential damage done to EV batteries, and thus reduced battery lifespan.

New research from the Hawaii Natural Energy Institute at the University of Hawaii at Manoa seems to clearly support this assertion — the extra cycling that accompanies use of an EV battery for grid balancing, even when at constant power, reduces EV battery cell performance significantly.

To be more specific, the use of an EV with V2G tech could reduce the working lifespan of an EV battery pack to under 5 years time, according to the new work.

The researchers note, though, that simply delaying the charging of EVs as a means of balancing the grid would have only a “negligible” effect on EV batteries, and could thus represent a better option. However, this could prove to not be the case in environments warmer than “room temperature.”

Green Car Congress provides more: “The Hawaii team performed laboratory testing on commercial Li-ion cells to investigate the impact of bidirectional charging on Panasonic 18650 NCA batteries. The researchers investigated the effects of V2G/G2V combined with different charging schedules (1 or 2 charges a day, immediate or delayed charging) and different charging currents (level 2 or fast charging). Further, the effect of calendar aging at different temperatures was also investigated in a second set of experiments.”

“The team concluded that a V2G step twice a day increased battery capacity loss by 75% and the resistance by 10%. This step once a day accelerated the capacity loss by 33% and the resistance increase by 5%. Forecasts based on the measurement results indicated that that V2G implementation would decrease the lifetime of the battery packs to under 5 years.”

“The team also found that calendar aging influenced the cells little enough that it was beneficial to charge the cells twice a day instead of once. Charging twice per day resulted in 5% less capacity loss and similar resistance increase compared to once per day.”

The new work is detailed in a paper published in the Journal of Power Sources.


Tags: , , , , ,


About the Author

James Ayre’s background is predominantly in geopolitics and history, but he has an obsessive interest in pretty much everything. After an early life spent in the Imperial Free City of Dortmund, James followed the river Ruhr to Cofbuokheim, where he attended the University of Astnide. And where he also briefly considered entering the coal mining business. He currently writes for a living, on a broad variety of subjects, ranging from science, to politics, to military history, to renewable energy. You can follow his work on Google+.



Back to Top ↑