These batteries are perfect for external flashes! I often take photographs and up to 5 Aufsteckblitze used parallel, I previously had a large wear on AA batteries. After no more than 200 trips even brand batteries went to his knees and let the loading time of the flashes are getting longer. Practically that meant to replace all 200 photos 20 AA batteries and dispose of. The whole thing was neither ecological nor okönomisch sense. Despite some doubts, which I cherish to batteries, I then got myself after reading many test and experience reports that Sanyo Eneloops. At first I thought the voltage curve during discharging is not possible and safe only fined ... then came the first practical application of Eneloops and I must say: I'm still excited! Depending on how the lightning is about 200-300 trips there, without greatly increasing load times. The batteries keep the tension for a long time before then taking a rapid end. This behavior is, of course 1000x more practical than the voltage drop (the second part of the word can be taken literally!) Of normal batteries. Combined with a BC-700 charger you can also find relatively well how the batteries voltage technically compatible. Either I was very lucky or it is actually selected before sale, because each per four-pack I had relatively equal voltage and capacitance values (deviation between the individual batteries 50mAh maximum in average 2050-2100mAh capacity) Convenient is also that the batteries are kept in white and thus can be marked with a permanent marker in "groups". This makes it easier for me to sort batteries with the same capacity and assign individual flashes.
A real must for anyone who photographed much with lightning!