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31 of 33 people found the following review helpful
on September 14, 2010
Re: 9V 250mAh NiMH high capacity rechargeable Battery

Buy them for your hi-drain devices... NOW!!!

I'm a musician (mainly keyboards but) I DO utilize 2 wireless giutars setups that need 9v batteries. I play about 10 times a month (4+ hours a night), so the Return On Investment was almost instantanious. Bought the 10 or 12-pack with the NiMH charger and can't be happier after a year and a half.

PLEASE NOTE: If you have flashlights or smoke detectors, NiMH batteries (simply by their design) are not intended for use where your device is rarely called upon (emergency/backup flashlight) or if your device requires a low but constant power source that's "on" for months at a time (smoke detectors). NiMH are not meant to hold a "long term" charge (and may have up to 40% loss of charge after 1 month). They're plimarily for hi-drain devices (Digital cameras, Wireless mic and guitar transmitters or constant duty flashlight and scanners) that need to be used for hours at a time until they need a recharge.

PLEASE ALSO NOTE: While researching NiMH batteries I found out you should get a 9V with a higher (250mAh) rating like Tenergy. Radio Shack 9v NiMH batteries are only rated at 125 mAh. They're both good batteries, but the higher mAh means the longer it will hold the charge. As a FINAL TIP, don't leave ANY batteries in your pockets unless they are the only thing in that pocket. I lost 3 because they shorted out against something else in my pocket, and since 9v have the + & - contacts next to each other... the more likely this is to happen. Mine didn't explode but they swelled up and got pretty warm in my pocket. Of all people, I sometimes forget this simple fact. Hope these tips help you in making your selection. Get the charger too, unless you already have a "NiMH" charger.

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36 of 39 people found the following review helpful
on March 1, 2009
The performance of these batteries has been surprisingly good! I've been using them for almost one year now. I use them in a set of Shure wireless mics (see my review of the mics on They have been doing an outstanding and demanding job. Their capacity is very good. Additionally, I feel environmentally green by using rechargeable battery. They pay for themselves after few recharges easy. I've been very happy with this product. Highly recommended.
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30 of 34 people found the following review helpful
TOP 500 REVIEWERon May 23, 2009
I bought two of these Tenergy 9V's for the smoke and carbon monoxide detectors in my kitchen (they came as part of a set: V3969A1 Plug-in Type Speedy NiMH & NiCd Charger with 14 cells (8AA /4AAA/2 9V) --New!!). I got fed up with the frequent replacement of alkaline 9V batteries. They'd last a month or two, then the alarm would start chirping annoyingly to indicate the need for replacement. Then I'd have to stand on a chair and tiptoe precariously to reach the ceiling mounted alarm and fumble with the cover.

Not being a well-known brand, I was unsure whether I would be able to rely on Tenergy. But after 8 months of using these and the other sizes, I am pleased with their performance and bought 12 more 9V's for the other detectors in the house and a TENS muscle relaxer. It has been at least 4 months since I inserted the Tenergy batteries into the detectors and they haven't needed recharging yet, so I am quite pleased with their life and energy capacity.

Their price to performance ratio is hard to beat. A regular alkaline Energizer at the local CVS is $5. They can only be used once. These can be recharged hundreds of times, making them very cost effective. (Tenergy claims up to 1000 charges, but real world performance will be a lot less).

Highly recommended.
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15 of 17 people found the following review helpful
on April 27, 2012
These are not good batteries. I bought 4 of these a couple of years back. Recently, two of these 4 stopped accepting a charge. My charger [Tenergy T-3969A1] won't even recognize them when inserted into the charger [charging light wont come on]. I researched into this issue on the `net and found out that sometimes the batteries get an open cell. I have not tried the revive methods suggested by some people on those two batteries.

At that point I suspected that the charger went bad so I bought a Maha Powerex MH-C490F Stealth charger. That charger also refused to charge the two bad batteries.

However when I tried to charge the other two batteries... both exploded after about an hour of charging. I suspected that the batteries cannot handle the fast charging action of the Maha MH-C490F charger. Did some research again... found out that the Maha Stealth is rated for 70-90mA. For comparison, I looked at Tenergy's own 9v charger - TN141. That is rated for 100mA. Also on Tenergy's own website says "Can be rapidly charged with our chargers model TN141, TN136, TN137, BC1HU, V1199B, V3969A1, V228. "

Hence it was definitely a bad battery and not the charger which caused these batteries to explode
OR, although these are listed to be capable of rapid charged, in reality, these batteries cannot be rapidly charged. These can be charged only by those old style chargers which put out only 15-16mA like the Tenergy T-228 or T-3969A1.

Interesting point:
The 2 batteries did NOT explode spectacularly; they cracked and the tops popped out. After looking closely I could see that 2-3 of the 8 internal cells had swelled up and leaking fluid.
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11 of 12 people found the following review helpful
on September 26, 2010
We bought 10 of these for wireless in-ear monitors at our church, intending for about a 3 hour use per day. They did not last more than 15 recharges before either failing to last that long or dying altogether. In four months time 5 of the 10 no longer hold charges at all. Very disappointed that we have to replace these so soon.
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16 of 19 people found the following review helpful
on March 9, 2009
They came charged and the spec's look good. I have used them now only a few weeks, but they are holding a charge as well as I'd expect. I'll report later if they disappoint me. For now though, I'd recommend. I use them for my DVM and other electronic devices.
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6 of 6 people found the following review helpful
on June 3, 2011
Before being put in a position to have to purchase rechargeable batteries we'd toyed with the idea with no real intention of actually jumping in and making this investment, we were wary about such an unknown and unpublished/unreviewed product.

Well, in 2010 I was in an auto accident which left me with a lovely permanent nerve/back injury and I was prescribed a T.E.N.S. Unit for the pain, which works fantastically, but EATS BATTERIES like there is no tomorrow.. so, I began researching rechargeable batteries, 9V specifically which is difficult to purchase in the stores by the way (go Amazon!, you always come through for us), and really couldn't find any concrete evidence that they were better than the consumable batteries.

SO, if you're toying with the idea, and teetering on the ledge of making this kind of investment and have any gadget that's eating your batteries I'll gladly push you off the battery buying cliff and tell you these are absolutely better than I'd ever expected. The Charge actually lasts longer than the standard run of the mill Energizer (consumable) and the standard Duracell (consumable), when you run low drop 'em back up on the charger and you're ready to go in a few hours, or less if you've invested in enough to switch them out. Bottom line, Tenergy rechargeable batteries while might be an uncomfortable and weary investment for the inexperienced is actually an absolute winner once you get into them. You'll never buy consumables again if you can help it!

Hope that helps you with your purchasing decision
Thanks for Reading!
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6 of 6 people found the following review helpful
on March 17, 2010
Purchased these batteries for my husband to use on his metal detector. The metal detector is a high drain device and he has been very pleased with the performance of these batteries. Price paid was alot cheaper than anywhere else I shopped locally.
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5 of 5 people found the following review helpful
on September 22, 2013
I purchased these several weeks ago. I have not contacted the seller yet.

I use them in a medical device. I go through several batteries a month.

Two of these go so hot in the case that they melted everything, including the contents of my plastic case.
No, the battery were not touching each other or any metal.

I am very upset. I can send photos of the battery's if you like.

This happened after I charged them for ten hours and put them in a plastic box with foam pads inside that keep everything in place.

The batteries are melted beyond recognition!

I am quite upset about the loss of my medical device and the fact that a fire could have started and hurt someone.

Oh, by the way the batteries were only in the box for several hours after charging them. My medical device is destroyed and now I have to contact my doctor and insurance for what to do next.

My unit is made of plastic and almost 1k to replace if I have to pay for it.
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5 of 5 people found the following review helpful
on March 30, 2011
I purchased a set of four of these batteries. Two of them holds no charges at all right from the beginning. The other two are so so. Before trying these, I used Radio Shack's own brand. They cost more but even after five years they work better than the new Tenergy.
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