Recommended external battery packs for 550EX speedlite?

I would like to speed up my cycling time on my external flash. i see that canon makes several

different types of external battery packs for the 550EX: the transistor pack 'E' with C

batteries or NiCD battery, and a couple of models using AA batteries - CP-E2 and CP-E3. if

anyone has words of wisdom as to the performance of these products, advantages and

disadvantages of various models, that would be great. also, are there any less expensive

third-party generics for this flash unit? thanks!

I was recently looking into the same questions and found these threads useful...<p>

 

<a href="http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=00AQ0d">Canon CP-E2 & CP-E3?</a>

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<a href="http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=00Atsn">Canon Battery Pack CP-E3 for 550EX/580EX</a>

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I decided on the CP-E3 to use with a 580EX if that matters.

I have no complaints about the Transistor Pack E. I use rechargeable NimH batteries in it and also in my 550 and the recycling time is almost nonexistant. You can also go all day long on a single set set of batteries.

The CP-E3 is an excellent unit and will go all day with extremely fast recycling time.

On mine I added an extra long bolt which goes through the unit and allows me to mount it

on the bottom of my flash bracket.

Quantum Turbo and Turbo Z will allow you to shoot full power flashes all day long with 1 to 2 second recycle times. Pricy but will last years. Well worth it.