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NiMH Batteries: Obsolete Technology or Suppressed EV Solution?

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By Forbes Bagatelle-Black

Nobody supports electric vehicle development more enthusiastically than Sherry Boschert. During a recent interview, she told me, “We’ve got about a ten-year window to stop burning carbon. After that, the worst effects of global warming due to greenhouse gas emissions will be unavoidable. We need to get lots of plug-in hybrids (PHEVs) on the road, and we need to do it RIGHT NOW!”

Boschert’s book, Plug-In Hybrids, The Cars That Will Recharge America is an eloquent, meticulously-researched work that lays out not only the history of PHEVs, but also a roadmap to making them a ubiquitous mode of transportation for Americans in the very near future. In the book, Boschert describes many obstacles hindering widespread production of PHEVs, but none are more important to her than the difficulties that EV developers encounter when they try to obtain large-format nickel metal hydride (NiMH) batteries. She details the series of events which ultimately resulted in Chevron Oil gaining control of the patents covering most large-format NiMH batteries. While she does not accuse Chevron explicitly, the implication is clear; Chevron, and the combined strength of the oil/automotive industrial complex, now controls the production of these batteries and they are going to squash the technology flatter than Los Angeles’s “Red Cars,” the streetcars which used to transport Angelinos everywhere until automotive interests allegedly bought them and dismantled the system.

Others agree wholeheartedly with Boschert’s conclusions. EV activist Doug Korthof recently referred to EVs using NiMH batteries as “the ONLY solution to global warming”. This controversy burns up an amazing amount of bandwidth on the blogosphere. Type “PHEV NiMH patent suppression” into your internet search engine and prepare for an avalanche of hits, ranging from well-researched arguments from the Green Car Congress to rantings from conspiracy theorists who seem to place more emphasis on emotion than facts. The activist crowd is firmly convinced that NiMH batteries could help save the planet if they were only given the chance.

But what about the people who build batteries and electric vehicles? Nobody at Cobasys, the company who officially owns the large-format NiMH battery patents, responded to my request for an interview. However, I did speak with several people who have a great deal of experience designing and building electric vehicles. Professor Andy Frank at University of California, Davis, has spent decades building a series of electric vehicles with teams of students. He has led groups building both vehicles which run solely on batteries (BEVs) and PHEVs. His teams have used both NiMH batteries and lithium ion (Li-Ion) batteries in their projects.

I asked Frank if Li-Ion batteries, which can store twice as much energy as NiMH batteries of the same weight, have rendered NiMH batteries technologically obsolete. “Not yet,” he responded. I asked him if the design of NiMH batteries is more mature than the design of Li-Ion batteries. “Yes, but Li-Ion is catching up fast.”

I went on to ask about the cost of Li-Ion batteries versus the cost of NiMH. Frank speculated about near-term cost trends, assuming both were mass-produced in similar quantities. “The present thinking is that they will be comparable in cost per kW*h but they [Li-Ion] are one half the weight.”

However, Frank has not dismissed NiMH batteries entirely. He acknowledges that they make more sense in PHEVs than BEVs because PHEVs do not rely solely on their battery packs to determine the ultimate range. He also praised the durability of NiMH batteries. “The metal hydride batteries I have are over ten years old and they still work. Lithium chemistry is too new to tell.”

Other “technical types” tend to be even more pro-lithium than Frank. JB Straubel, chief technical officer at Tesla Motors, feels that NiMH batteries are nearly obsolete “given the increasing performance and falling price of Li-Ion.”

Tom Gage, president of EV-maker AC Propulsion, echoes Straubel’s thoughts. When I asked him if NiMH batteries were obsolete, he said “For hybrids, no. For full-function EVs, probably yes.”

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