I came across an interesting posting called NIMH batteries Held Hostage by Chevron-Texaco and I realized how big of an issue it really is. Currently plug in hybrids are forced to use lead-acid or lithium batteries even though the NIMH batteries last longer, drive an EV at 80mph for up to 120 miles, and have 1500 charges (150, 000 miles before they need replacement). The reason behind this is because GM purchased control of the patent, which was later bought by Chevron and Texaco, so no car companies can make hybrid vehicles without their permission. The frustrating part about this is that the NIMH went into production in 1997! That was 13 years ago and yet this technology cannot be used because of a “patent.” Car companies are only allowed to use NIMH batteries if they have consent from Chevron even though companies, like Toyota, already have the technology to make it. Therefore, Toyota can only produce plug in vehicles if they think of another battery technology or until the patent expires in 2014. And this is all because GM, Chevron, and Texaco want to continue making money from gasoline operated cars!
Read more about it at http://fuel-efficient-vehicles.org/energy-news/?p=690