You could shim your noid .. by putting a nickel or something behind the solenoid ... but that doesn't help much either ... i tried a nine volt .. got 2 shots and it sorta died out ...
I would just get
This ... it's two batteries .. and you get it for the price of 11 bucks.. it says it includes a charger too .. it's hard to believe.. and i havn't tried it myself yet .. so if you want .. give it a shot