Just bought a 580 EX II

Wow, I cant believe I did it. Lot of money! I am going to need it for three weddings I am shooting in April and May and the vivitar 285hv I have ain't going to cut it. Does anyone know if you can get through a full day of shooting a wedding with a good brand of batteries? I saw a battery pack on amazon for $40 that holds 8 AA batteries but I'm not sure I'm going to need it.

You'd be silly to start a wedding without at least 12 batteries fully charged and ready. Or more.
The usage depends on so many variables, that there's no way we can estimate.
Day? Night? What aperature will you want to shoot at, and will you be in HSS mode?
How fast are your lenses? What ISO is your camera capable of shooting at with acceptable grain?
If you're asking this question, you don't have a good familiarity with that flash in those situations.
Pack 20

Look into Sanyo Eneloop rechargeable batteries. I have found them the best.

I don't think you want to consider shooting with flash without a battery pack. You'll need the fast recycle at times. You could probably get by with the 12 batteries (4 in flash, 8 in pack). It'd be smart to have 24.

You're the main photographer, or second?

ootsk wrote in post #12035515
You'd be silly to start a wedding without at least 12 batteries fully charged and ready. Or more.
The usage depends on so many variables, that there's no way we can estimate.
Day? Night? What aperature will you want to shoot at, and will you be in HSS mode?
How fast are your lenses? What ISO is your camera capable of shooting at with acceptable grain?
If you're asking this question, you don't have a good familiarity with that flash in those situations.
Pack 20

Sorry, I should of worded my question differently. I would definitely have extra batteries on hand I was just debating on the battery pack so I won’t have to worry about swapping batteries during the wedding to save time. That was mainly my issue in this thread.

You'd be surprised how fast you can change batteries when need-be. That said, I shoot about 10 a year so far, and have never wanted anything more than the internal batteries.
People will argue till the end of time with me, but that's my opinion.
I think a key is to change them before they go out. Maybe it comes with experience, or maybe just luck, but depending on the factors I mentioned earlier, I know when my batteries need to be replaced. If I'm using it heavy in the church, I make sure to swap before the last kiss, so I can get them coming towards me at the aisle. I might put fresh ones in for the formals. I always put fresh ones in for the grand entrance and first dance. Cake cutting/garter stuff also. Dancing at the end, I might let them ride a little longer.

ootsk wrote in post #12040967
I think a key is to change them before they go out. Maybe it comes with experience, or maybe just luck, but depending on the factors I mentioned earlier, I know when my batteries need to be replaced. If I'm using it heavy in the church, I make sure to swap before the last kiss, so I can get them coming towards me at the aisle. I might put fresh ones in for the formals. I always put fresh ones in for the grand entrance and first dance. Cake cutting/garter stuff also. Dancing at the end, I might let them ride a little longer.

Thats how I do it. Also if my recycle time dips any I change them.. Lets just say I burn through some batteries..

Thanks for the advice.

sometimes I use a battery pack, sometimes I don't...
but definitely always carry a few extra sets of Eneloops/Duraloops (and an extra flash)

+1 for eneloop!

Sounds good! I Just got the flash and its amazing.

IMAGE LINK: http://www.flickr.com …icholascaputo/5​536974563/

Nice shot!! Flashes make a huge difference, and ETTL is very useful in many situations.. Congrats!