I recently purhased a used CP-E4N external battery pack to power my 580 EX II. However it does come with an instructional.
When the CP-E4N is connected to the flash,wiil the LED light up. Mine lighted up momentarily; should it not light up "steady" instead of momentarily?
Keep your eyes open for any extra 'battery trays' that may show up on the used market. It's especially useful (and fast) to swap pre-loaded battery trays, rather than fumbling around to remove spent batts from the tray, and then load fresh ones into it. Also, the little tabs that hold the batteries in place on the tray, often break off. The tray still works, but you have to help it keep the batteries in place, until it goes into the power pack.
