The driver is rated up to 9v as tested by other DX testers and verified by myself. I use a 2 xSSC cube helmet light with that driver in there with a 6xAA NIMH battery holder. The battery holder ot off the charger reads 8.5v and I've tested it with a used 9v battery from a smoke alarm which was reading 8.91v before testing it on the driver and the driver had no problems with that. I've not tested on a fresh 9v battery yet as if I recall right fresh 9v batteries are about as high as 9.5v fo rthe normal alkalines and didn't want to blow the driver.

BTW overkill is always good. > That's why we have dimming modes for so when you don't need to kick that overkill to full blast you can dim it down.