1 reviews

Tenergy Rechargable AA

$7.99 Released January, 2010

Product Shot 1 The Pros:Charger works efficiently, always reliable. Charger has many slots available for simultaneous charging of a lot of batteries. Charge up quickly, without the need for any special chargers.

The Cons:Charger is bulky, not easily transported. Typically last a little less than advertised. Batteries unable to put out high amps.

info The below section of the report appears to be written as a first-person review.
Please rewrite in original words from a neutral point of view, and if you're the writer, please move this to the comments section.

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I purchased two dozen AA NiMH batteries from All-Battery.com in an ebay auction on January 19, 2008 for home use.  Twelve were to be for me and twelve for a friend.  I purchased these specifically, because the price was good and they came in a package deal, including C and D adapters.  The adapters seemed like a good idea for three reasons.  1)  you need fewer types of batteries on hand, to always have charged AA, C and D cells, 2) most chargers are only for AAA and AA cells and 3) true high capacity C and D NiMH batteries are very expensive, and the cheaper ones are really just AA batteries in a larger shell.  This was fine, because the particular uses for C and D cells that we have, Roomba virtual walls, are low drain and the more rapid turnover for the AA batteries would be acceptable.


Upon receiving the batteries, I charged all twelve of mine and tried them out.  It turned out that they did not work in my Cateye LED bike light or in the controller for my radio-controlled helicopter, two main reasons I needed them.  Comparing them with other AA batteries, it seems that the problem is that the positive terminal of the Tenergy batteries stands a little less proud from the body than the others, and the aforementioned devices happened to have plastic bosses around the positive terminals, so that the positive terminals of the batteries could not reach those of the devices.  I contacted All-Battery.com about this, and they referred me to Tenergy for technical support.  The Tenergy tech support person  assured me that the batteries met the IEC specification and offered me a 50% refund.  It was not clear if I had to send the batteries back and only 50% of my money would be refunded or they would refund 50% of the money without taking the batteries back, but I didn’t clarify this, as I thought I might add a little solder to the terminals to make them work – I did not get a chance to try that.   


In the applications where the batteries did work, they seemed OK initially, but lost their charge very rapidly.  My friend tried newly-charged ones in her Roomba virtual walls one day and they worked, but a few days later they did not. She also put them in her wireless computer keyboards, but they only lasted a couple of days, while other brands last several months. I put a newly charged pair in my etrex GPS one weekend and went on a hike, but the next weekend they were dead.  It seemed that the batteries were running down very fast between charges, so I decided to do a test.  I charged 12 batteries and measured the voltages.  I found that the voltages were lower than the other NiMH batteries I had (Sony and Ultra).  I also found that they discharged faster than other batteries and were very weak after one week.  I unfortunately lost that data, but I wrote to All-Battery.com and Tenergy again, asking for a complete refund.  They never answered my email, so I decided to do another test and write this review.


I charged 12 Tenergy cells and 2 Ultra cells.  The Tenergy cells were bought January 19th 2008 and the Ultra cells were at least two years old but in excellent condition.  I had bought them from Globalcomputer.com.  I measured the no-load voltage of all cells immediately after charging and a couple of times over the next three weeks.  The results for all 14 cells are plotted individually in the graph below.  Even at time zero, all Tenergy cells had significantly lower voltage than the Ultra cells, by 68 mV on average, and the discharge rate was much greater, so that after three weeks, the Tenergy cells were on average 190 mV lower than the Ultra cells.  After the three week measurements I tested pairs of batteries in a 2-cell Maglite.  The Ultra cells lit the bulb brightly with no noticeable decrease during half an hour of  continuous operation.  On the other hand, all six pairs of tenergy cells produced a very dim light that extinguished completely within 30 seconds.


In conclusion, the Tenergy cells I received are defective in three ways. 1) they have a nonstandard positive terminal size that makes them unserviceable in some devices. 2) the fully charged voltage is lower than that of other NiMH cells and 3) The no-load discharge rate is much higher than that of other brands.  I can’t see how any customer could be satisifed with this performance.  I think that I may have gotten a bad batch or the comments from satisfied Tenergy customers I have seen on their site were from customers who had just tried their batteries after charging them.  In either case, it is unacceptable.

User Reviews (1)

Add Pros & Cons
  • 1

    charger works efficiently, always reliable

  • 1

    charger has many slots available for simultaneous charging of a lot of batteries

  • 1

    charge up quickly, without the need for any special chargers

  • 1

    much lower-cost than equivalent rated rechargeable batteries on the market

  • 1

    compatible with a wide range of chargers

  • 1

    can be recharged again and again, last a long time

  • 1

    charger is bulky, not easily transported

  • 1

    typically last a little less than advertised

  • 1

    batteries unable to put out high amps

  • 1

    devices that require 4 AA batteries often will not receive adequate power

Comments (8)

What's on your mind? See more ProductWiki Talk
Harry: #tenergy_aa_nimh_batteries I have a 4 cell AA/AAA Energizer charger that came with Energizer 2500 mAh NiMH batteries. (1) I assume that the charger is not limited to recharge only Energizer or only up to 2500 mAh batteries - am I correct? (2) Is charging only one battery at a time in a 4 slot charger same as using a charger that charges each battery separately? (3) Does the discharge rate during initial (10X) cycling affect long term performance/potential? Thanks Dec 26, 10
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Prepared: #tenergy_aa_nimh_batteries We've been using Tenergy batteries extensively for over year and are very pleased with them. Like other NiMH batteries, they need to be cycled several times to reach their peak but they last quite a long time under heavy use. We use them primarily in high-powered LED flashlights and the R2Us hold their own against our Sanyo Eneloops. The Sanyo 2700s last a bit longer, but they are also three times the price. I even use the Tenergy AAA's in a Cree flashlight that takes AA cells. I use AAA-to-AA adapters. Very pleased with the performance.

For the money, the Tenergy cells are a great deal and they perform well. Just remember to cycle them several times and if you decide to throw them away, throw them my way. I'll cycle them and use them for years. Dec 8, 09
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Jigar Patel
Jigar Patel: #tenergy_aa_nimh_batteries Oh, forgot to mention: I have been using Tenergy batteries for 3 years and counting Oct 2, 09
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Jigar Patel
Jigar Patel: #tenergy_aa_nimh_batteries I must agree with rgoers. I have been using Tenergy batteries in everything from Toys, Remotes, Wireless Keyboard, Mouse, etc. and they do last very long time. I always "Refresh" each new battery before putting in circulation. "Refresh" meaning go through charge-discharge cycle for about 10 times. I use "La Crosse Technology BC-9009 AlphaPower Battery Charger". This charge charges each battery separately and has built-in "Refresh" mode that watches capacity of the cell. "Refresh" mode in this charge will charge-discharge each cell until the mAh capacity stabilized and maximized. Oct 2, 09
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rgoers: #tenergy_aa_nimh_batteries

Folks, folks, folks... you have to understand how NiMH batteries work! You MUST put them through several charge/discharge cycles before they reach their full potential! Additionally, you have to use a GOOD charger if you want them to work at peak performance.

I have had a set of 24 Tenergy AA batteries for a couple years now, that get quite intense usage. I could not be happier with them. I use them for everything from LED flashlights, Wii controllers, to the transmitter unit for my R/C Nitro boats. I even put a set in my outdoor landscape lighting unit. They last all night now, unlike the NiCAD batteries I replaced. I've cycled these batteries hundreds of times, and never a problem. I bought my son a set of genuine SONY high-capacity NiMH batteries for a cordless soldering iron (talk about current draw...). The Tenergy batteries perform as well or better than the SONY brand (which cost at least 3X).

In summary:
1) Get a decent charger, one that charges EACH battery separately (not in pairs).
2) Cycle the batteries @10x before judging them.

Nov 21, 08
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squirrel11779: #tenergy_aa_nimh_batteries I got had, I bought the 68 cell set with charger kit.
I put C and D size in my mag-lights and they worked fine for a few months.
The AA & AAA are horrible the AA don't last two days in my digital camera.
I originally bought them for my daughters toys but I have to charge them so frequently it has become more of a hassle than it worth.
Has anyone tried contacting the Better Business Bureau?

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sthnguyen: #tenergy_aa_nimh_batteries Same problem with Tenergy AA batteries. I purchased 40 AA batteries since they were almost as cheap as alkalines. At first everything seems alright but then I noticed that they did not seem to work after a few uses. I realized that they do cannot hold a charge. I tested two of random batteries in my charger that has a test mode and found the capacity to be 0.036mA and 360mA for another and will test the rest. Given that two random batteries are pretty bad doesn't bode well for the rest of the batteries.

I have Tenergy C and D size batteries and they work fine. They hold their charge over at least three months and they are still working but I will definitely try to stay away from them in the future regardless of the battery size.

What it comes down to is either Tenergy had very poor quality control by not testing the batteries after production or knew they were bad and shipped them anyways (which is fraudulent). Either way, it is unacceptable as Mattb had put it.

Word of advice. Stay away from Tenergy AA batteries. Sep 30, 08
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mattb: #tenergy_aa_nimh_batteries Junk batteries, worse than non-alkalines
I had a similar experience. My 16 AA batteries from Tenergy self discharge to 0.6v within a week and straight from the charger would not last more than 10 mins in a low power 2 cell LED flashlight, by comparison my Sanyo Eneloop AA's last 5 hours in the same flashlight and are rated lower amp-hours than Tenergy. Their customer service rep said I should use Ni-cads due to the high self discharge rate of their batteries.

Unacceptable and NOT recommended Jul 24, 08
comments (1)
  • Anonymous

    Anonymous: The blue Tenergys tend to be crap. I had a set of C size once, and they were horribly mismatched. Right now, they got rid of the blue ones, and have the new premium line, the white Tenergy Premium. Their Nicads are still mismatchy. There are not many choices with the C and D cells. Imedions are pricy, and Accupower Evolution is no longer making theirs, but they had good D cells. (can't say the same for the other sizes) The new Tenergy premiums hold up far better under heavy load vs any others people are tried, read the thread ( Accupower evolution quality gone..) Tests were done with ultra high demand flashlights. Mar 18, 13

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