A Texas shell company is claiming that battery technology in devices like the Kindle Fire and the Samsung Galaxy Nexus infringes its patent.

In three lawsuits filed this week, Unifi Scientific Batteries claims that Amazon (NSDQ:AMZN - News), Barnes & Noble (NYSE:BKS - News) and a group of phone and tablet makers violate US patent 6791298, “Monolithic battery charging device.”

The patent appears to relate to a process for recharging a battery:

A monolithically formed battery charger may be fabricated as an integral part of a multifunctional integrated circuit or as independent monolithically formed integrated circuit. The monolithically formed battery charger includes at least one step-down converter having a given duty ratio coupled to a battery-terminal interface that provides a stepped-down output voltage and current that may be used to charge a rechargeable battery.

The patent was issued in 2003 and has since passed through a series of shell companies until it was acquired by Unifi last October. Companies like Unifi, known as patent trolls, typically serve as alter-egos for lawyers and investors that make a business of collecting patents and suing companies that produce goods.

The other defendants and products named in the lawsuit are: Research In Motions’ Playbook and Storm 9530; Barnes & Noble’s Nook; Samsung; Texas Instruments; HTC; Nokia; (NYSE:NOK - News) Sony.

Apple (NSDQ:AAPL - News) and Microsoft (NSDQ:MSFT - News) were not named in the lawsuits.

The lawsuits were filed in the U.S. District Court for Eastern Texas which has long been a popular venue for patent trolls.

Here’s a copy of one of the complaints:

Unifi v RIM and Phone Industry