Battery Maker ESS Tech Accused in Suit of Hiding Link to Client

ESS Tech Inc., which makes industrial-scale energy storage batteries, allegedly touted a partner that was later criticized as its “de-facto subsidiary,” according to a new investor complaint.

A short-seller report by Grizzly Research describes Energy Storage Industries Asia Pacific, based in Australia, as having little activity outside its work for ESS, according to the complaint, filed Thursday in the US District Court for the District of Oregon.

“ESS misled investors with their partnership announcement to signal business success to investors,” shareholder James Wakefield says on behalf of a proposed class.

Wilsonville, Ore.-based ESS disputes the allegations. The Grizzly research report ...