hello all-im fresh to the forum and metal detecting.i just bought a bh ultra mag thinking this might put some excitement in my life and have not even tested it yet. i live in the midwest and winter just keeps holding on so im waiting for the warmer weather to get here to try it out.in the manual it says to only use alkaline batteries it does'nt warn against using rechargeables.it takes the 9 volt batteries.does anyone have any experience using these in bounty hunters?will thet damage my unit?or should i just stick with the tried and true.thanks all-