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152 of 155 people found the following review helpful
Ordinary 'high-capacity' NiMH cells typically advertise charge capacity of 2500-2700mAh (for AA), but they all suffer from rapid self discharge problems. That is why I switched over to low-self-discharge (also called 'Pre-Charged') rechargeable batteries more than four years ago, starting from the original SANYO eneloop. Over the years I have tested many other name-brand LSD cells such as Rayovac Hybrid and Kodak Pre-Charged, all with great results.

The only drawback of LSD cells is lower capacity. First-generation LSD cells are typically rated at 2000-2100mAh. Recently, I have seen arrival of second-generation LSD cells with higher capacity, such as these IMEDION AA 2400 mAh low self-discharge batteries. Here are my test results, using the La Crosse BC-900 battery Charger/Analyzer:

- Right out the package, the average remaining charge is 1880mAh for a set of four Imedion AA cells. This is about 78% of the rated capacity, which suggests those are indeed low-self-discharge type (ordinary NiMH cells typically arrive exhausted)

- After just one Charge/Discharge cycle, the average capacity improved to 2455mAh, or 2% higher than rated capacity. This number remains the same in subsequence cycles. Again, this performance suggests that those cells are LSD type (ordinary NiMH cells typically takes ~5 cycles to slowly approach their rated capacities)

Just for comparison, here are my test results for other brands of LSD cells:
Sanyo Eneloop XX: Rated 2500mAh, measured ~2600mAh (4% higher)
Yuasa Enitime PLUS: Rated 2500mAh, measured ~2400mAh (4% LOWER)
Lenmar R2G AA: Rated 2150mAh, tested ~2030mAh (6% LOWER)
GP Recyko NiMH AA: Rated 2100mAh, tested ~2230mAh (6% higher)
UltraLast Green Everyday Precharged: Rated 2100mAh, measured ~2200mAh (5% higher)
- SANYO eneloop (2nd-gen): Rated 2000mAh, measured ~2130mAh (6% higher)

The measured capacity of IMEDION AA cells (2455mAh) is higher than all others except for Sanyo XX (2600mAh). However, as of this writing, the Sanyo XX costs nearly twice as much as the Imedion. That makes those Imedion LSD cells a much better deal compared to Sanyo XX. When comparing Imedion to Sanyo eneloop, you pay ~15% more for ~15% increase in capacity. So again, this makes the Imedion a great deal.

One important side note: The Imedion AA cell is quite a bit thicker than normal alkaline cells. So they may not fit in appliances with tight battery compartments. This is actually a common problem with high-capacity NiMH cells. I don't have a pair of calipers to measure the cell diameters. But in term of relative 'fatness' of various AA cells, I can arrange them in the following order:

IMEDION > Sanyo XX > Sanyo eneloop > Rayovac Hybrid > Alkaline

[Update on Oct 23, 2011]
Tested a pair of Imedion AA after 5 months in storage. The average remaining charge is 2125mAh, or 86% of the original capacity (2470mAh). This charge retention rate is almost as good as that of Sanyo eneloop.

[Update on Mar 31, 2013]
Tested a second pair of Imedion AA after 17 months in storage. They retained 75% of original charge. This means the Imedion's self-discharge rate is just slightly faster than that of eneloop. For all practical purposes both are excellent.
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23 of 23 people found the following review helpful
on December 26, 2009
The charging and quality aspects have been covered in great detail and I have nothing to add there. Just be aware that these cells have a slightly shorter + terminal than is usual so there will be a few electronics where they will not work. I have a new Ebook reader and 2 radios where they are a no go so be advised. Some battery compartments can be bent a little to accommodate this problem, others cannot.
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146 of 173 people found the following review helpful
on March 26, 2009
As I googled the Internet and Forums, I found mixed result, some people claims Eneloop performs better, and some claims otherwise. Therefore I decided to do an experiment on both of these batteries to find out which one is a BETTER PERFORMER and better for investment.

Objective: To find out the better performer battery

Items:
1. Four pieces of Sanyo Eneloop AA 2000mAh NiMH Battery
2. Four pieces of PowerEx Imedion AA 2100mAh NiMH Battery
3. Nikon Speedlight SB-800
4. Remote Flash Trigger
5. Process recording device (Sony DSC-P10)

Methodology:
1. Fully Charge the battery
2. Insert battery into Nikon Speedlight SB800
3. Nikon Speedlight SB-800 set to M 1/4 -oEV
4. Fire the Speedlight as soon as it is ready (when the red light is on)
5. Repeat step #3 until the battery is completely depleted
6. Record the following:
a. X number of shots per minute after X number of shots
b. Total shots per charge
7. Repeat the process with next set of battery

To ensure both battery both are in identical optimal condition, I bought both new set of Eneloop and Imedion. Both sets are new and fully charged for 8 hours as recommended by manufacturer for initial use with the same PowerEx MH-C204W Travel Charger before begin the test.

Please refer to the graph my site.

I started off with Eneloop with a recorded blazing fast 60 round per minute (rpm). It drops to 53rpm after the first 100 shots, and then it drops further to 52rpm after 200 shots. It stabilized at average of 45rpm from 300 shots to 1300 shots. It drops to 39rpm at 1400 shots and drops further to 37rpm after 1500 shots. Finally it drops sharply but still managed to squeeze a total recorded 1564 shots. Pretty impressive for first round.

I followed by Imedion immediately. At the initial minute it has a noticeable lower refresh rate compared with Eneloop and I recorded a 51rpm for the first minute, lower than Eneloop 9rpm. It then dropped 20% performance to 42rpm after the first 100 shots. After 200 shots, it stabilized at average of 39rpm from 200 shots to 1200 shots (compared to 45rpm Eneloop). It drops slightly to 36rpm after 1300 shots to 1500 shots. Then it drops further down to 17rpm after 1600 shots. Finally it is completely depleted at 1660 shots.

Conclusion:
Eneloop completed at 1564 shoots and Imedion completed at 1660, approximately 100 shots more than Eneloop, which is pretty much expected as it is a 2100mAh vs 2000mAh, with approximately 5% extra power. For a fair comparison, I only benchmark up to 1500 shots, which is already beyond what average number of photos a person can take on a whole day event (with speedlight)

On cycle performance point of view, Eneloop out performed Imedion from 4rpm to 14rpm with an amazing everage of 6rpm on a consistant performance.

In this experiment, I concluded that the Sanyo Eneloop is a better performer than PowerEx Imedion, at least in speedlight point of view.

Full review, graph, experiment results are available in my blog at: [...]
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12 of 12 people found the following review helpful
Ordinary 'high-capacity' NiMH cells typically advertise charge capacity of 2500-2700mAh (for AA), but they all suffer from rapid self discharge problems. That is why I switched over to low-self-discharge (also called 'Pre-Charged') rechargeable batteries more than six years ago, starting from the original SANYO eneloop. Over the years I have tested many other name-brand LSD cells such as Rayovac Hybrid and Kodak Pre-Charged, all with great results.

The only drawback of LSD cells is lower capacity. First-generation LSD cells are typically rated at 2000-2100mAh. But by now, we have seen arrival of second-generation LSD cells with higher capacity, such as this PowerEx Imedion Precharged 2400mAh AA Rechargeable Battery. Here are my test results, using the La Crosse BC-900 battery Charger/Analyzer:

- Right out the package, the average remaining charge is 1880mAh for a set of four Imedion AA cells. This is about 78% of the rated capacity, which suggests those are low-self-discharge type (ordinary NiMH cells typically arrive exhausted)

- After just one Charge/Discharge cycle, the average capacity improved to 2455mAh, or 2% higher than rated capacity. This number remains the same in subsequence cycles. Again, this performance suggests that those cells are LSD type (ordinary NiMH cells typically takes ~5 cycles to slowly approach their rated capacities)

Just for comparison, here are my measured capacity numbers for other brands of LSD cells:
Sanyo Eneloop XX: Rated 2500mAh, measured ~2600mAh (4% higher)
Yuasa Enitime PLUS: Rated 2500mAh, measured ~2400mAh (4% LOWER)
GP Recyko NiMH AA: Rated 2100mAh, tested ~2230mAh (6% higher)
SANYO eneloop (2nd-gen): Rated 2000mAh, measured ~2130mAh (6% higher)

About long-term self-discharge rate: I tested a pair of Imedion AA after 5 months in storage. The average remaining charge is 2125mAh, or 86% of the original capacity. A second pair was tested after 17 months, and retained 75% of original capacity. That means the Imedion's self-discharge rate is just slightly faster than that of Sanyo eneloop, but similar to that of the Sanyo XX. For all practical purposes all three are sufficient.

[Conclusion]:
The measured capacity of IMEDION AA cells (2455mAh) is higher than all others except for Sanyo XX (2600mAh). However, as of this writing, the Sanyo XX costs about 50% more than the Imedion. That makes Imedion LSD cells a much better deal compared to Sanyo XX.

[Important note]:
The Imedion AA cells are quite a bit thicker than normal alkaline cells. So they may not fit in appliances with tight battery compartments. This is actually a common problem with high-capacity NiMH cells. I don't have a pair of calipers to measure the cell diameters. But in term of relative 'fatness' of various AA cells, I can arrange them in the following order:

IMEDION > Sanyo XX > Sanyo eneloop > Rayovac Hybrid > Alkaline
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11 of 11 people found the following review helpful
on April 25, 2012
I bought two sets of these batteries just a little over a year ago and at first they seemed great. They had the highest capacity of any NiMH batteries that I have owned. They averaged a little over 2300 mAh with the lowest being 2270. The battery states the minimum is 2250 mAh. Also I've read that my charger prematurely ends the charging cycle on low self discharge batteries so that probably explains the less than rated charges. This was more than acceptable though because they easily outlasted my eneloops in my police scanner, which is what I bought these for. I only listen to it over the weekend, usually around 16 hours a day for three days. With the eneloops two sets of batteries wouldn't quite make it the whole way and usually would die a couple of hours before I needed them to (usually got around 23 hours of use out of each set). With these Imedions I was getting over 54 hours of use out of my scanner (more than 27 hours per set). About ten months after I started using these batteries I noticed they were slowly starting to go dead sooner than they had previously. I used the "break in" function on my charger and that seemed to help for a few weeks. Then they once again start to slowly die sooner. Now I'm lucky to get 23 hours of use out of each set which is about the same as I was getting with the eneloops. Testing the batteries confirms that I'm barely getting 2000 mAh of charge with the batteries now, which is the same as with my eneloops. My eneloops are over two years old and have shown no such degradation. They've been charged less than 100 times and I always use a charge rate of 800 mA or less so I don't believe I've damaged the batteries. Maybe I just got a bad batch but given my experience I can't really recommend these batteries nor will I purchase any more in the future.

**UPDATE 6/16/2013**

It's been over a year since I wrote this review and over two years since I bought these batteries so I thought I'd do a quick update. Two of the batteries will no longer charge at all and the remaining six now average under 1800 mAh. Due to this I have changed the rating to two stars instead of the original rating of three. I recently ordered and received two sets of Eneloop XX batteries so hopefully those will turn out better than these have.
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4 of 4 people found the following review helpful
on January 12, 2012
First, there are plenty of great reviews of these batteries from other folks, so I'm not going to bother writing up all the technical detail! In short, these are about the best low-self discharge rechargeables you can currently get, in my experience; other reviewers go into this in more detail.

My one problem with these batteries from Amazon is that the product page is vague as to whether you're getting the retail package, or if you're getting a re-packed bulk battery. The picture should reflect what you get, but I ordered based on the picture with one order, and the order history page showed separate batteries...yet I did get the retail packaging that time. Another order, product page and confirmation showed the retail packaging, but I got the bulk packaging! Go figure. I've actually noticed slightly higher capacity from the retail packaging (~2460mAh average across 8 batteries from 3 different packs) than from the bulk packaging. (~2390mAh average across 6 batteries from 2 different packs.) In other words, the bulk packaged ones tend to be around or slightly below the advertised capacity...but the retail packaged ones tended to be slightly above it. (All these tests are taking the best value from 4+ tests on a La Crosse BC-700.)

So, I don't know because my sample size is really too small, but it's possible Maha is shipping slightly-lower-capacity batteries for the bulk packages than the retail blister-pack with the original Maha case. I've actually stripped batteries from both types, and the manufacturing codes on the retail packs are significantly different than the bulk ones; I don't know if this actually means anything...but it does also lend some evidence to the two types being manufactured in separate batches, for unknown reasons.

As far as Amazon sellers go, I've noticed that Thomas Distributing sells the bulk packaged batteries...the ones I've ordered from Micro-Tools are in retail packaging but cost the same AND definitely tested better. I'm not sure if the Thomas Distributing one wasn't also a customer return on top of the bulk packaging though, only testing to 2300 - 2350mAh for that batch and all arriving with < 50% charge! I'd blame Amazon for accepting a bad return where that goes... I actually excluded those from my results above, or the number would be even worse for bulk packaged ones! (Around ~2350mAh average if I did include those.)

I don't know about other sellers, but it may be worth checking beforehand...and if anyone has noticed whether any other sellers than those two sell the retail pack vs bulk pack, I wouldn't mind a comment to that effect. :) (And if anyone has noticed capacity differences between the two!)
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4 of 4 people found the following review helpful
on February 1, 2012
Let me start off by saying that these batteries are simply amazing. Like you, I sometimes look for an extra small ticket item to round out my purchase and get free super saver shipping; The Imedions were one such purchase. I thought these would be just like any other rechargable batteries, but I was wrong. I've been using rechargeables for about 15yrs. now, and these are perhaps the best that I have come across. I use rechargeable batteries for everything in my household and recharge them with a La Crosse charger, another great product. Where I have noticed a vast improvement with these batteries is with my Denotte Bicycle light. If you have a bike that uses AA batteries, you already know that next to photography, probably nothing punishes batteries more. It used to be that I could only get 1/2 way through my ride when my Low Bat. indicator would flash, with these I can take 2 commutes the same distance before they give up the ghost. I also used to have to make sure that my AA batteries were freshly charged before a ride, with these.... not so much! Rechargeable batteries already save me close to $70 dollars per year, with the Imedions I estimate a even better value because they don't need to be charged as often, that saves me electricity as well as battery life. All rechargeable batteries advertise that they can be recharged X amount of times before they need to be trashed... Ahem, I mean recycled, and it is true, recharging and discharging takes a tole on them, so the less you have to constantly charge a battery to make sure it is ready for action, the more years said battery will be around! Excellent battery, I think I am sold on these and the more expensive but equally as good, Enloops.
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7 of 8 people found the following review helpful
on September 26, 2011
The title surely says it all. These were purchased only because they perfectly fit the Magic Flight Launch Box. They are actually the same batteries that are shipped with the device. Sure there are much better batteries out there, however these were used for a singular purpose and work quite well.
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8 of 10 people found the following review helpful
on November 9, 2010
This is a great battery. I am seeing ~2400mAh as indicated by my MH-C9000 charger which is as I expected. I haven't had the batteries long enough to know if they live up to their long term storage capacity, but judging by Maha and other products on the market now, I have little doubt. These are great batteries in any event at 2400mAh and the low self discharge features of these new batteries from a known and established company known for its quality (Maha).

I would give these batteries five stars, but $14.99 for four is expensive when they can be found elsewhere (i.e. Thomas Distributing) for less than $11 for four.
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13 of 17 people found the following review helpful
on January 22, 2008
My fully charged set of Imedion AA batteries give me on average 10% more shots with my DSLR than my Eneloop, which has long been the sole power source for my camera. I have not tried Panasonic Infinium or other hybrid brands so no comparison there. Considering the price to performance ratio I am a very happy user of these made-in-Taiwan NiMH's. Highly recommended!
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