eCost12 Acuvar High Capacity AA Rechargeable Batteries 3100mAh NiMH

You have to read the fine print. These "3100"mAh batteries are 1.2V, not 1.3V, which makes these closer to a 1.3V 2800mAh equivalent on paper (only 2.72Wh at 1.2V vs 2.77Wh at 1.3V). The problem is lower voltage effects electronics in ways that a simple mAh rating will not predict.These batteries hold their charge fairly well in low-duty applications - but in high draw electronics they do not perform very well. This is mainly due to their 1.2V specification. In other words - the 3100mAh rating is deceiving due to the fact most high-output NiMH batteries have their rating spec'd at 1.3V. To someone with little experience in the field of electronics 0.1V may not seem significant - but in reality it is, especially in sensitive electronics.The real word service comparison that I can provide is in a Yale z-wave dead bolt - and it's noteworthy. I have seen comparable service out of standard 1.5V alkaline batteries and 1500mAh 1.3V NiMH batteries. The rated Watt-hours would not suggest this - but the lower voltage (and proportional voltage drop-off over time) cause this battery to approach a device's minimum voltage much sooner, and therefore stop working. The battery may still have a charge - but it's not a useable charge due to the lower voltage.

Will be using these in harsh colder than normal climates will let you know how it goes

Best battery ever. Plays my 1 hour nightly cd over 6 times before replacing fresh batteries. They keep their charge a long time. Run clocks for a year, and my toothbrush for 6 months. use on mp3, for 10 to 15 hours of play.

We are unable to keep much of a charge on the Acuvar batteries. In other words, they act as if they have been used a thousand times and are ready for recycling. I do need to verify, however, if we need a different charger. Thanks.

Many nimh batteries are thicker than standard AAs, but these are no bigger than normal AAs. Last a long time in everything from Xbox controllers to microphone packs to led video lights. Couldn't be happier so far!

Works. Great and I use them every day and still recharging them. They last very well. Jerry

I charges them and they don’t work. I tried them in several items. Trash can flashlight. Tv remote. They didn’t work at all

These batteries seem to hold a charge for a long time. I use them with wireless microphones and I can run several hours on one charge.