If you're really serious about using a powerful strobe outdoors but without spending the thousands it usually costs, take a look at the Bowens heads and, specifically, the TravelPak that powers them outdoors. I picked up my 500R head for $525 and the battery pack for $384. I also grabbed a spare battery for it for $160.
Combined, they'll see me get north of 400 shots on location without breaking the bank. The only concessions are no modelling lamp and a longer recycling time.
The pack is pretty small though.
Or you could blow $7000 just on a pro power pack...