OTTAWA, Dec 19 (Reuters) - Energy storage developer EEStor Inc, a key partner of Canadian electric car maker Zenn Motor Co (ZNN.V), has secured a U.S. patent for its battery, its chief executive said on Friday.

Low-profile EEStor is working on an ultracapacitor battery that is smaller and will charge faster that traditional batteries.

Zenn holds the worldwide exclusive rights for use of that battery in vehicles under 14,000 kilograms (3,086 pounds), a market that Paradigm Capital analyst Marvin Wolff estimates at about 30 million vehicles annually.

"All patents are always important," Chief Executive Richard Weir told Reuters, but declined further comment.

Zenn also declined to comment.

Wolff said EEStor also has a European patent pending for its barium titanate nano-capacitor battery.

"EEStor should now be nearing the point were it can release its ... data and unveil its battery to the public," Wolff wrote in a research note.

Toronto-based Zenn has paid EEStor $1.3 million of a $2.5 million investment commitment, pending milestones, and has a 3.8 percent equity stake in the Texas company.

Zenn currently sells a low-speed electric vehicle with a top speed of 40 kilometres per hour (25 mph) but has promised to launch a highway-capable car by the end of 2009.

Powered by EEStor's energy storage system, the new car is expected to have a top speed of 125 km/h (78 mph) and travel 400 km (250 miles) on one charge.

Shares in Zenn gained 4 percent, or