To many the title of this post may surprise, as it is not a favoured battery at Wolf Eyes. Having just released a AA torch and also being aware that many of our clients use AA batteries in their night vision goggles, communications equipment, etc and just about all of us have houses full of AA and AAA batteries I thought it appropriate to test some of our options. Up front I will say that for economic and environmental reasons I favour rechargeable batteries.
I had a few choices when reviewing these batteries, I am also an enthusiastic photographer so two options sprang to mind, use a high powered incandescent globe or use a high powered external camera flash. I chose the flash option as I could leave the camera tethered to a computer taking photos every x seconds, then later review the photos to see when they went black. If I chose a globe I would have to be there to watch the batteries go flat. So the below review is what I posted on a photography forum, I would like to see this work be of use to as many as possible and if it encourages the use of rechargeable batteries all the better.
Like many of you with flashes, I have a reasonable collection of rechargeable AA batteries. In fact I would say more than reasonable, I keep on finding AAs everywhere, from the central heating controller which I haven’t used for 9 months, in remote controls, in my PSD, etc, etc. These batteries are everywhere through my house, even in the keyboard and mouse I am writing this with now. I would conservatively say there are 100 rechargeable AAs in my house. This got me thinking, at about $5 per battery, I probably have $500 tied up in rechargeable AA. It is not even my favourite style of battery! I prefer Lithium ion as in cameras, mobiles and notebooks and regard AA as a lightweight consumer battery. After reading comments on this board and elsewhere, I wondered a) if the claims made about some batteries being slow discharge and capacity are true and b) was I using the best charger to look after my (unknown to me) $500+ investment? I also like to encourage the use of good rechargeables, as the cheapskate in me prefers to spend $5 on a battery and use it 500 times, than spend $1 on a battery and use it once. Far, far more important is the fact I would prefer to throw one rechargeable AA into landfill than 500 disposable AA batteries.
I tend to review batteries occasionally, choose the best for my needs at that time, then continue buying that battery till conditions change. For the last few years I have bought Eneloops as their Low Self Discharge suits my usage patterns well. I think that is one point that people should think on, what their usage patterns are. I tend to leave items idle for extended periods, then want them available for instant use. Eneloops do this and work as a direct replacement for any AA battery, non LSD don’t do this as they discharge without use. If my godsons drop in, I can grab my flash, take a dozen shots, even if I haven’t used it for a few months. That suits me where a pro photographer may prefer a slightly higher capacity battery which needs to be charged the day before the shoot, so that they are at maximum capacity for the shoot.
Having decided it was time for a review of my battery choices, I obtained the new Low Self Discharge battery, the Imedion by Maha. If the claims were true, it held a small capacity increase over the Eneloops, 2100mah to 2000mah while being the same price. Maha is also well known on places like Candle Power Forums and often described by members there as having the best AA charger in the world. (have you ever seen someone describe a product as the 9th best in the world? ). The charger with the big reputation is the Maha Powerex MH-C 9000, so I obtained one as well, especially after I realised it was $10 cheaper ($89.95) than my previous most expensive charger, the Powertech Computer Controlled Smart Charger MB 3511 at $99.50 from Jaycar. I obtained this from servaasproducts . This charger has the ability to analyse as well as charge which I thought would be useful for my tests. I also will be selling a consumer level AA torch soon so could justify the research and costs for a charger which really analyses the battery.
The batteries. Naturally I chose my favourite, the Eneloop and as far as I can tell, the only other genuine LSD battery is the Imedion. If I was going to all this effort I thought I should compare it to a better non LSD battery, so chose the widely respected Energizer 2500mah. To give something to keep them honest in the non LSD section, I also got a pack of Powerex 2700mah. I don’t view these batteries as competitors necessarily with each other, more the Eneloop with Imedion and Energizer with Powerex. Let the games begin.
Methodolgy. I am more than happy to have others criticise my methodology as there are many here who have a greater understanding of batteries and electronics, so please feel free to question anything. I wanted to test in a way which was meaningful to photographers, so hopefully my tests will provide that.
I decided to get each set of 4 batteries and put them through the ‘refresh analyse’ function of the charger. I then fully discharged the set in a separate ‘discharge’ cycle. I then fully charged the set in a separate ‘charge’ cycle, but also kept a record of the capacity of each cell, as described by the charger. These numbers are what is available below. After charging, each set of 4 was put into a Nikon SB800 flash. This was connected to a D300 which was then connected to a laptop with Camera Control Pro. The 105mm lens was set to manual focus and aimed at 2 sheets of A4 2 metres away, then the flash was carefully aimed out the window at the neighbour who objected to my Development Application. There was enough spill to light the paper. The SB800 was set to M 1/1 105mm F29 so using plenty of power. I also used the SB800 on 4 batteries, so to give an absolute base level result which most should do better than and to save me buying more packs of batteries than the one I choose. I set the time lapse section of Camera Control Pro to 20 seconds, meaning the camera and flash produced a full flash power shot every 20 seconds, then recorded it to my hard drive. This was convenient as I could stop recording when seeing the flash stop, then review the images till I found the first dark image and count how many flash shots were obtained. I believe this was a fairly successful way of testing, as when the flash stopped I would discharge the batteries for test 2, in all cases the batteries registered discharged in less than 30 seconds, indicating they were fully spent. All batteries (bar the Energizers which must be shipped empty as they took half an hour to discharge) had taken 3-5 hours to fully discharge. I should mention I used the stock discharge and charge rates on the charger, but could have varied them in 100mah increments if I wished.
Electronics experts will be able to tell me what I was measuring in the above test, the battery capacity or recovery or both? I don’t know. To eliminate the recovery part to focus more on capacity, I used the exact same test procedure as above but changed the rest interval to 40 seconds, twice as long. The results of these tests are below:
Capacity – 1st test
Eneloop 1927,2065,1878,1841 average 1927 mah
Imedion 2048,2098,2058,1933 average 2034 mah
Energiser 2266,2385,2446,2379 average 2369 mah
Powerex 2537,2628,2609,2553 average 2581 mah
Flashes at full power with 20 seconds rest:
Eneloop 204 flashes
Imedion 218 flashes
Energizer 242 flashes
Powerex 266 flashes
Capacity 2nd test
Eneloop 1914,1984,2015,1940 average 1963 mah
Imedion 2091,2150,2141,2141 average 2130 mah
Energizer 2362,2445, 2466,2386 average 2414 mah
Powerex 2533,2664,2677,2633 average 2626 mah
Flashes at full power with 40 seconds rest:
Conclusions. First I would say it was pleasant to discover that with quality brands the rated mah is roughly accurate. All of the batteries tested were close enough for a cheap bulk consumer item to their specs. By comparison, my neighbour had left some Prolink 2500 mah rated batteries in my PSD when he borrowed it, testing those revealed a capacity in the 1400 mah range!
I view the batteries as 2 different styles, my main interest is in LSD as it suits my usage patterns and I am able to recommend it to customers as a direct replacement for a disposable battery with no education required. So comparing the two LSD batteries, both are good and have close to their rated capacity. The Imedion is rated 5% higher in mah than the Eneloop (2100mah v 2000mah) and in the 20 second test produced 6.8% more flashes, in the second 7.6% more flashes, roughly in line with the claimed capacity difference.
The Powerex is rated 8% higher than the Energizer and in the first 20 second test produces 9.9% more flashes and in the 40 second test 10.8% more, again roughly in line with the claimed capacity difference.
I would be happy to use any of the tested batteries in my flash. As my usage patterns demand LSD and much of the point of this test is to be able to recommend to clients a LSD battery as a direct replacement for normal batteries, my recommendations (if you have similar usage patterns) would be the Imedions. Also I am a bloke, and as any self respecting bloke knows, you always get the 7% more powerful version if they are the same price. So the Imedions have become my new standard till the next improvement in battery technology.
If you are a pro photographer who has the time and discipline to recharge their batteries the day before they use them, I would recommend the Powerex. Neither Powerex or Energizer would be my first pick for most people, I would suggest a LSD battery first.
There will be 2 more parts to this test, I am now going to rate the chargers after this to see if there really is a difference or it is all just nice screens to make me feel if I have got my money’s worth and as a second test I will charge all 16 batteries and put them on the shelf for 3 weeks (just before my Camera Control Pro trial expires) and retest then.
As it seems that the chargers indication of mah is directly reflected in flashes, I am more than happy to test a sample of any batteries, so if you have a set of 6000 mah AA made of unobtainium you think are the best, send them over. Feel free to ask any questions and make suggestions where the process could be improved.
Part 2 of the AA rechargeable tests: http://wolfeyes.com.au/news/?p=8
Part 3 of the AA rechargeable tests http://wolfeyes.com.au/news/?p=9
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