Using NiZn batteries in my 580EX flash, I can get off a second or third shot very quickly. Because I don’t normally use machine gun techniques, I don’t worry too much about overheating the 580EX. Fire one! OK, fire two! Wait a minute, what happened! No flash?
To my chagrin, three of the eight NiZn batteries that I bragged about only a year ago have gone bad. They will not hold a charge over time and, right out of the charger, output voltage drops from about 1.8 volts to less than 1.2 volts after about ten full power flashes. Not acceptable.
My first thought was that, perhaps, the charger was recharging batteries in pairs and that the problem was simply a matter of the recharging procedure. To compensate, I recharged the four battery set then switched the batteries around several times and recharged again. No difference in performance. Then (instruction manual) I learned that the NiZn charger will work with 1, 2, 3 or 4 batteries.
At this point, I’m not quite sure what to do. The second set of NiZn batteries, purchased about six months ago, seem to work fine. I’ve been using the NiZn batteries in my flashes routinely but that doesn’t equate to heavy usage. My plan is to continue to use the NiZn batteries but to monitor performance carefully.
I sure like the fast recycle time but is it worthwhile if the batteries last only six or eight months?