Patent encumbrance of large automotive NiMH batteries

Patent encumbrance of large automotive NIMH batteries means that certain companies have a patent on the technology that makes NIMH batteries, so that no other company can use that technology without the permission (or 'encumbrance') of the patent holder. This means that companies that want to use NIMH batteries for their products have to get permission from the patent holder to use the technology, which can be difficult and expensive. So, if you want to buy a car, phone, laptop, etc. that uses NIMH batteries, you might find that the battery is more expensive because of the patent encumbrance.