« on: February 19, 2012, 12:58:40 AM »
I use only eneloop and imedion LD-NiMH batteries in my speedlites (because they're recommended by Syl Arena) and have no regrets, I charge them in a Powerex charger. I also use Energiser re-chargables in equipment such as mouse and keyboard, I sometimes charge my energisers in the powerex charger, but would never charge the eneloops and imedions in the compact energiser charger that I have- it doesn't auto switch off when the batteries are full whereas my powerex does, and the powerex has fast and soft charge options as well.
I simply pack a set of spare fully-charged eneloops or imedions when I'm using my speedlights(and CP-e4), I find they hold their charge well for re-chargables.
Dido, I too took Syl Arena's advice and use Eneloop LD-NiMH (low discharge) for ready to go and Powerex NiMH for when I have time to charge. I use the Powerex Maha MH-C801D charger with 8 bays that has a condition, 1 hour (rapid), and soft charge modes.
I learned the hard way not store batteries in your Speedlight. Canon charged me $100 to repair a alkaline battery leak in my 580 EX II.
Edit: The leaked alkaline battery was a Rayovac. At the same time as my damaged 580, I also had a leak in one of my 430 EX IIs, also Rayovac alk. Based on what others have posted, never store alkalines in a flash unit and store rechargables with caution.