When my 4th Grade son had the opportunity to work on his elementary school’s annual Science Fair recently, the idea of doing this test came about. I made some revisions to his final report to suit the POTN forum’s purposes, but still some words of caution that we didn’t set out to do an exhaustive or the most comprehensive and meticulous scientific project on battery tests. In other words, use our report here as just a rough guideline for making your own decisions.
We photographers rely heavily on “AA” batteries for many of our lighting gear, particularly our hot shoe flashes, external battery packs, and other accessories, and we often prefer those rechargeable NiMH kinds over disposable alkalines for economical and environmental reasons. Yet, these NiMH rechargeables can be quite confusing – and very often frustrating! – with all different kinds that are being sold in the market today with all varying degrees of performance satisfaction. For one thing, there are just too many brands with different “mAh” (Milliamp-Hour) ratings with different prices. There are fast recharging “15-Minute” kinds, “Low Self-Discharge” (even “Ultra Ultra Low Self-Discharge”!) kinds, “Ready to Use” kinds, “Hybrid” kinds, and so on. And as the newer battery manufacturing technologies grow, we’ll be seeing more unfamiliar kinds grow, as well, I’m sure.
So, which one to get?
Is there just one kind and one brand that would rise to the top as the “BEST” of them all? Is there such a thing? That’s what we wanted to know, and what I want to share here.
We decided to purchase those rechargeable “AA” batteries that were most popularly mentioned here and elsewhere (9 different kinds in all from various stores), but we also decided to throw into the mix one alkaline battery kind (Energizer Max) as a referential interest.
All tests were conducted in the ambient indoor temperature fluctuating between 63F to 72F.
The tests were conducted in the following five key usage points of interests:
1) “Ready to Use” right out of new package. How true and reliable are those brands that claim that their batteries are ready to be used right away?
2) “Shelf Life” for testing the rate of self-discharge. All batteries were fully charged prior to conducting the test (with the exception of Energizer alkaline).
3) “Camera Flash Pops” – we tallied 6,560 pops after all was done! We decided to employ the Canon Speedlite 300EZ from my old film photography days as an ideal for such flash “abuse” as opposed to using my 580EX. Although the 580EX would have been perhaps more useful for those who do own the same flash, you can compare the difference in the output level by consulting the following as a reference:
Guide Number (at ISO 100):
Zoom Position (mm): at 35
Canon Speedlite 300EZ: Normal Flash = 25 (83)
Canon Speedlite 580EX: Normal Flash = 36 (118.1)
The flash was popped only when the capacitor was full, indicated by the pilot light being “red.” The flash was given 5 minutes to cool after a series of 20 pops. Each set of 4 “AA” batteries were tested using the ZTS Pulse Load Multi-Battery Tester after each 100th pops until the 500th pops or when the recycle time took too long to be of significance. In order to be accurate the percentage power remaining was only recorded when the ZTS Tester gave the consistent reading three times on each battery. Since not all 4 batteries in a given set read the same power remaining, the power average was calculated by adding the remaining power divided by 4.
4) “Camera Flash Recycle Time” – Used the same method of popping as the above. A stopwatch was used at the first five pops and the average recycle time was recorded. The “start” point was at the moment the flash fired and the “stop” point was when the pilot light turned red. After the initial time was read, the recycle time was read at each 100th juncture with the average recycle time read at the last 5 pops of each juncture, for example, 95th-100th, 195th-200th, 295th-300th, and so on.
5) “Flashlight” – in addition to the higher current, Canon flash popping test, this lower current test was conducted, as well. A set of two fully charged batteries were placed in a common household flashlight with the power switch turned on. They were pulled out of the flashlight and tested after the initial two hours. Thereafter, they were tested each hour for the power remaining until they were completely drained.
6) “The Best ‘Low Self-Discharge’ VS. the Best ‘Performing’ Battery” – After all the tests were done, we had a rather obvious confirmation of our hypothesis that there is no one “BEST” battery that is the clearest winner in all categories. However, there were clear winners in different categories. So we decided to test the winner in the 1) “Ready to Use” and 2) “Shelf Life” (low self-discharge indicators) tests combined with the winner in the 3) “Camera Flash Pops,” 4) “Flash Recycle Time,” and 5) “Flashlight” (performance indicators) tests.
We placed these two winners in a head-to-head duel with the “Camera Flash Pops” test (using the same methodology) ONE week after being fully charged, and another sets of these winners THREE weeks after being fully charged. Why one to three weeks period? That’s because most of us photographers use the rechargeable batteries within that time period after a full charge. We wanted to find out the time it takes for the higher self-discharging battery to lose its power below that of the low self-discharging battery. We of course knew that the lower self-discharging battery will beat the higher self-discharging battery – sooner or later. The question is how long, particularly within the three weeks time period? We could have done in one, two, and in three weeks period, but we felt that the tests done in two separate occasions were enough.