Just thought I’d slip this in: Canon warns against using lithium-ion batteries in speedlights (flashes) due to the potential to overheat. http://www.canonrumors.com/2014/12/canon-usa-warns-against-lithium-battery-use-with-speedlites/ From my understanding, l-i batteries have plenty of capacity, but aren’t designed to discharge quickly, and if you do a lot of repeat flashing, or strobing a speedlight could overwork the l-i technology, damaging both battery and flash unit. I’ve no experience with this and can’t say how much of a problem this is, but I’d take canon’s word for it.
