For the B10N001 you would need 10 AA NiMhs/NiCads for it to run properly. You would need the B10N004 to run on 8 NiMhs/NiCads. You can however run it safely on 8 AA alkalines.
If I remember correctly, my B10N001 starts to flicker when batt voltage hits the 10's on 123s. I've only got to that point once as I try to change the batts before the flickering starts just to ensure a longer life of the ballast. (Hey you can never be to safe than sorry. I've seen automotive HID ballasts burn out before the user finds out that the daytime running lights on their car was causing the flickering due to low power output.) Excessive flickering may shorten the life or damage the ballast if left flickering continuously. 8 NiMhs/NiCads would give you only 9.6 which would probably cause it to flicker if not shortly after.