Ener1 Inc., the struggling parent of Indianapolis-based advanced-battery maker EnerDel, is being booted from the NASDAQ stock exchange, according to a public filing by the company.

New York-based Ener1 said in a filing Tuesday with the Securities and Exchange Commission that it would be suspended from the exchange starting Thursday due to non-compliance with filing requirements. Ener1 said it did not plan to appeal the suspension and would be permanently removed from the exchange.

EnerDel employed about 350 people in the Indianapolis area at the beginning of the year. The division produces lithium-ion batteries used for hybrid cars—mostly the Think—and for power-grid storage.

A delisting will relegate Ener1 shares to penny-stock status on the over-the-counter bulletin board. Once that happens, shares are more difficult to buy and sell.

According to the SEC filing, Ener1 failed to meet an Oct. 17 deadline to file a quarterly report for the period ended June 30. In addition, the company said NASDAQ determined that Ener1 violated shareholder approval requirements in amending a line of credit.

Ener1 already was in danger of losing its NASDAQ listing because its stock price has not met the $1-per-share minimum price requirement to trade on the exchange since July. NASDAQ warned the company in September that it was not meeting listing requirements.

Ener1’s shares tumbled from more than $4 a share in January, when Vice President Joe Biden visited EnerDel’s Greenfield battery plant, to less than a dollar in a matter of months. Shares traded at 20 cents each Wednesday morning, down 6 cents since Tuesday’s close.

The company has experienced a series of setbacks this year. Most recently, several lawsuits have been filed, claiming the company misled investors about its financial condition.

Investors began filing the suits in August, days after 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.

Ener1’s auditors said in an August SEC filing that there were growing cash-flow concerns regarding the company and doubts about its ability to continue operations.

EnerDel was formed in Indiana in 2004 when Ener1 began acquiring the lithiom-ion battery operations of Delphi Corp. Ener1 has attracted millions in federal grants and state and local tax incentives, based on its technology and growth plans.     

It previously received a $118.5 million U.S. Department of Energy grant and has applied for $290 million in federal loan guarantees.