Click here for an archive of Cramer's "Mad Money" recaps. Jim Cramer is charged up about the stock of EnerSys ( ENS) after a caller brought up the company on his radio show Thursday. After looking into it more, Cramer believes EnerSys is a "major buy," he told viewers Friday on his "Mad Money" TV show. EnerSys makes industrial batteries that are used for backup power. It's a sleeper industry, said Cramer, but one he believes is in bull market mode given the need for backup power as demonstrated during the recent hurricanes. Cramer said the company sells to the telecommunications industry, the military and hospitals, all of which could use more backup power. At a multiple of one times sales and 13 times 2007 earnings estimates, the stock is too cheap, he said. Additionally, at Friday's regular session closing price of $14.24, the stock isn't too far above its 2004 public offering price of $12.50. The risks in the stock as Cramer sees them include that more than half the company's outstanding shares are held by insiders. So, if the stock goes up a lot in a short amount of time, Cramer wouldn't be surprised to see insiders selling. Additionally, the company has a lot of debt and not much cash, he said. The company also gets 40% of its revenue from telecommunications companies, which means any downturn in the telecommunications sector could spell trouble. EnerSys may be risky, said Cramer, but there are plenty of great reasons to own the stock. If you can buy the stock within 50 cents of Friday's regular session closing price, Cramer believes the trade will be profitable. But, if you have to pay up $2 or more, take a pass and wait for the next idea, said Cramer.