Good morning! I am in need of some advice/help. I have a Canon 5d Mark ii and 5d Mark iii. I have two Canon speedlites, the 580 ex ii and 600 exrt. I also have the Canon battery back up that is connected to the flash I am using at the time. In addition, I use rechargeable third generation eneloop batteries for all of this. At a wedding,I have to hold out using my flash for quite a long time, because I'm having big issues. My camera can be set anywhere from iso 400-600, f stop 4-7.1 and speed from 1/15 to 300. After I turn on my flash (using ettl as the setting), I take 5-7 pictures and the screen on the flash comes up with a picture of a battery with a line through it and shuts off.... both flashes do this. I've seen people take 100 pictures, without a battery back up and have no issues. The eneloop batteries aren't even warm! Even after a wedding, my eneloop batteries take 30 seconds to fully charge. Any help would be greatly appreciated. Thanks for listening!