An investor at Maxwell Technologies Inc. on Monday lodged the latest challenge to Tesla's planned $218 million acquisition of the small manufacturer of energy-storage products, saying that the Maxwell board had failed to disclose information regarding potential conflicts by the firm's financial adviser.

The class-action complaint, filed by Maxwell investor Davis Rodden, targeted the company's board and sought additional discloses about Barclays Capital Inc.'s current and prior engagements outside of the all-stock deal, which was announced last month.

In the filing, Rodden and his attorneys said San Diego-based Maxwell had agreed to pay Barclays $4.87 million for advisory services, with most of the investment bank's compensation contingent on the deal's completion. The information, they said, was “patently material” to stockholders' upcoming determination on whether to support the transaction.

“In order to fairly assess the proposed transaction and determine how to respond to the offer, and to assess whether to rely on Barclays' fairness opinion in making that determination, Maxwell stockholders, such as plaintiff, are entitled to know all material information concerning Barclays' conflicts of interest,” the complaint said.

“Without disclosure of this information, Maxwell stockholders are left guessing as to whether Barclays' conflicts of interest tainted the process, and will be unable to make an informed decision as to the proposed transaction and determine how to respond to the offer.”

According to court documents, on Feb. 3 the Maxwell board approved Tesla's offer to acquire the firm at a value of $4.75 per share, in a deal that would give Tesla and CEO Elon Musk access to Maxwell's stock of ultracapacitors, which store and transfer energy more effectively than than traditional primary energy sources.

Maxwell's products are largely geared toward automotive, heavy transportation and renewable energy applications.

“We believe this transaction is in the best interests of Maxwell stockholders and offers investors the opportunity to participate in Tesla's mission of accelerating the advent of sustainable transport and energy,” Maxwell chief executive officer Franz Fink said in a press release at the time.

A company spokesman, reached for comment Tuesday, said it was “Maxwell Technologies' practice not to comment on ongoing legal matters.”

Last month, a separate group of Maxwell investors sued in San Diego federal court to halt the deal, saying the process was “unfair” to investors.

The Chancery Court lawsuit, on the other hand, asks for additional disclosures for stockholders—a type of case that has gone out of style in Delaware after the state Supreme Court affirmed the Chancery Court's landmark rulings in the cases In re Trulia Stockholder Litigation and Corwin v. KKR Financial Holdings.

As a result, attorneys and observers in Delaware have noted that class actions stemming from mergers, once a staple of the Chancery Court docket, have migrated to federal courts around the country, amid heightened scrutiny from state court judges. In the Court of Chancery, the cases are now evaluated on whether the disclosures in question alter the “total mix” of information available to investors.

Rodden is represented in the case by Blake A. Bennett of Cooch & Taylor Attorneys at Law in Wilmington and D. Seamus Kaskela of Kaskela Law in Newtown Square, Pennsylvania.

An online docket-tracking service did not list counsel for the Maxwell directors.

The case, captioned Rodden v. Bilodeau, has not yet been assigned to a judge.