That battery is way overkill for the strobe. The strobe draws about 140 mA so each battery would power it for about 32 hours.

I think the Velleman strobe -- the one that you can get from All Electronics for $9 that everyone uses (http://www.allelectronics.com/cgi-bi...-3A&type=store) -- can run on 9 volts. I'll check the data sheet when I get home. If that's the case, you can just hook it up to a rectangular 9V battery, using one of these: http://www.allelectronics.com/cgi-bi...-51&type=store. Red to red and black to black is all you need to know to hook it up. It should run for about 4 hours on an alkaline and about two hours on a rechargeable.

If it truly needs 12v, there isn't a quite so simple solution.