A federal judge in New York as early as this week could chose a lead plaintiff from among at least three lawsuits accusing the parent of Indianapolis-based advanced-battery maker EnerDel of misleading investors about its financial condition.

Investors began filing the suits in August, days after New York-based Ener1 said it would restate earnings for 2010 and for the first quarter of this year.

Ener1’s 2010 financial loss of $69 million eventually was restated to a loss of $165 million.

The restatement stemmed from write-downs in the company’s investment in Norwegian electric car maker Think, which was behind in payments to Ener1 for batteries.

Think, which assembles cars in Elkhart, filed for bankruptcy this summer. It has since been been acquired by investment group led by Russian entrepreneur Boris Zingarevich, who also is a major investor in Ener1.

Smaller investors who filed suit since August allege that Ener1 made false and misleading statements about Think’s true condition and failed to make timely impairment to the value of its Think investment.

Ener1’s shares have tumbled from more than $4 a share in January, when Vice President Joe Biden visited EnerDel’s Greenfield battery plant, to about 27 cents per share in recent days. The company expressed concerns about its ability to stay afloat in regulatory documents filed in August.

According to federal court records, the largest group of investors filing suit appears to have lost an aggregate $379,891.

Proving “loss causation” in such lawsuits can be a challenge. Courts have raised the burden of proof for plaintiffs to show a misstatement caused them financial loss.

“You have to prove the information was material and that the information that was missing caused the loss,” said Irwin Levin, a partner of Indianapolis law firm Cohen & Malad, which has successfully prevailed in such suits over the years.

Ener1’s Indianapolis-area operations at the beginning of the year employed about 350 people. Company officials declined to comment on the recent lawsuits, saying they are in a quiet period amid the earnings-restatement process.

The Indiana operations produce lithium-ion batteries used for hybrid cars—mostly the Think—and for power-grid storage. Ener1 also has struck preliminary agreements to supply batteries for electric cars in China, and is slated to provide batteries for a Volvo hybrid station wagon.

The company applied for $290 million in federal loan guarantees and is awaiting word on approval. It previously received a $118.5 million U.S. Department of Energy grant.