Tenergy Centura 9V NiMH Rechargeable Batteries Low Self Discharge 200mAh Square Batteries For Smoke Alarms Pack Of 2

I have a clock radio that uses a 9v battery for backup in case of power failures. When the power goes out the clock display shuts off to save power but the battery allows it to still keep time and if your alarm is set it will go off as usual. The clock has a low-battery warning light to let you know when to replace (or in my case recharge) the battery.I was using one of the first old style NiMH 9v batteries that was not low self-discharge that had a 150mah capacity and I think around 7.2v output. When it was fully charged and I put it into the clock radio it would take literally 3 or 4 seconds for the low battery light to come on. Obviously the battery didn't have a voltage above the threshold of the warning light so it came on immediately and stayed on. The battery did have enough power to run the clock if we lost power which was good, but it was annoying that I didn't have any way to know when the battery was drained. I found out through trial and error that the battery would only last about two or three months due to it self-discharging over that time. And that was without any power outages.So I went with this new low self-discharge 9V battery to see what would happen and couldn't be happier. It has a higher voltage so now the low battery light stays off (at least so far). I ordered these along with theTenergy TN141 2 Bay 9V Smart Charger for NiMH 9V Rechargeable Batteriesand gave the battery a quick charge to top it off before use. It has been about a month now and I just picked up theDelkin Devices DD/BATTEST MULTI RoHS AA/AAA Battery Power Testerand checked the charge level and it's still showing a full charge which is excellent, the old battery would have already been down to around 50% charge at this point. I will use the battery tester on it again when the low-battery light comes on, I may be able to use it for a while after the light comes on depending on it's charge level at that time.Over time as my other 9v alkaline batteries fail in my smoke detectors and other devices around the house I will definitely be replacing them with these. There really isn't any reason to stay with standard alkalines batteries over these new low self-discharge type of rechargeables anymore, with a few exceptions where rechargeables just aren't a good option for a particular device. But for the majority of our devices these are the way to go, saving us a lot of money over time. Using these batteries is most likely going to eliminate having to ever buy alkaline 9v batteries again since each one can be recharged up to 1000 times. That's a nice chunk of change saved right there. For each of these new 9 volts you bought you would be saving 1000 times the cost of a 9v alkaline, which even if they sold for only a dollar apiece you would save $1000! That's absolutely ridiculous. In a "I really like that" ridiculous kind of way!These modern low self-discharge NiHM batteries are another small but helpful innovation that makes our lives just that much easier. Highly recommended.*** Update Sunday, June 10, 2012This discussion got me wondering, when using NiMH low self-discharge batteries, just how long would a smoke detector give you low battery warnings, until the batteries discharged completely and the warnings stopped?I had a Kidde NightHawk combination smoke/CO2 alarm that I could test with and like a lot of newer alarms it takes AA batteries, so I tested some Imedion AA low self-discharge NiHM batteries (three). I discharged the batteries until they were down to about 25% full, put them in and then had a long wait until I heard the first low battery warning. The alarm manual stated that using alkaline batteries the low battery warning would last at least seven days. I figured that the way these batteries discharge quicker than alkalines at the end of their life that the warning time would definitely be shorter than seven days, maybe around 2 to 5 days. However, what I found was the complete opposite! To my great surprise I actually ended up stopping the test myself before the batteries were completely exhausted. Why? Because the alarm gave me constant low battery warnings FOR THREE FULL WEEKS. I really didn't need to see just how much longer they were going to last past that.So apparently the low voltage cutoff point that triggers the warning was high enough that the NiHM LSD battery still has sufficient voltage to keep the warnings going for a long time, before it hits the steep (and quick) drop off point. So maybe a NiHM LSD 9V battery like this Tenergy might last longer than you would think as well, depending on the device used. Maybe we'll hear about how a 9V battery fares from someone in the future, either on Dropy or posted elsewhere.

I own a lot of NiMH batteries ... mostly AAs & AAAs, but I do have a fair amount of C, D and 9V.Before I give my review, let me state the importance of having a good quality Battery Charger. I typically use a Tenergy T9688 Battery Charger & I have an identical C. Crane-branded model as the T9688. If you don't have a decent charger, you won't get satisfactory performance from ANY NiMH battery! Choose a charger that (1) Reconditions batteries; and (2) Can identify batteries with bad cells that need to be discarded (recycled).I have found these Tenergy LSD Low Self Discharge 200 mAh 9-Volt batteries and the [regular] Tenergy 250 mAh 9V to be the best 9V NiMH batteries that I have used. Both retain a charge for a long time - especially these LSDs. As an example I've switched over all 7 of my home's smoke detectors with a mixture of both and I've found them to be reliable and durable - nearly the same life (before needing a re-charge] as throw-away Duracells. I would not use these in something as important as smoke detectors if I did not have complete faith in their performance! And since they are Green/re-chargeable, you save money within a short period of time & help the environment.Note: If you do use these in Smoke Detectors, just ensure you have a few spares to replace a "chirping" smoke detector battery when they get low and set-off the Low Battery chirp/alarm.

These batteries work well for recharging many times. They are medium quality and will charge over and over for a good amount of time. They don't last as long as more expensive batteries.

I bought my first of these a long while back. And I wasn't impressed initially. The battery felt light for a 9v, materials felt cheap. But happily a long while later, I've been pleasantly surprised.These rechargeable batteries hold a charge for a long time. I originally bought them for Rocksmith. I don't play the game much but had bought a cheap acoustic electric to do so. The pickup like most of them do require a 9v battery. I popped it in and even over a year later, the charge was good. I recently had an issue with a smoke detector. The 9v Duracell batteries I'd bought for them originally-- by the time I had to use them, they were long expired and like 3 years old. It didn't occur to me that they'd run out of juice before I even got a chance to use them. I pulled the battery from my guitar which hadn't been used but three or four times and was months... think like 18 months since I last recharged. They held the charge well enough that it's been over a week in my smoke detector and it's still not beeping low battery. I've long since charged a backup but it may be a long while before I have to swap them. I'll be using these as my replacement and backup 9v batteries from here on out. Even if they run down in between 3 or 4 year swaps, I can recharge them-- and I just don't believe they would take longer to drain than sitting inside the smoke alarm/detector.

They work well. Saves money on batteries with my t.e.n.s. If you have a tight budget they are much more affordable on Dropy than the independent companies. Would recommend!