I have two sets and alternate them in a portable radio.
I've tried normal rechargeables and found that, often, they either go flat in the radio when it's unused for a week or flat in the drawer waiting to be used. These don't, and are claimed to be able to retain at least 70% of their charge for several months. I've never had any problems with them going unexpectedly flat, and they charge up just like any other rechargeable battery.
I wouldn't claim that this particular brand is special, I'm sure other manufacturers batteries of this type will do much the same job.
I'd given up on rechargables for any device that didn't trickle charge when not in use. These have changed my mind.
Our household has a strategy of moving entirely to rechargeable batteries now that the technology has come of age. These Panasonic Infinium batteries represent a good balance between cost and power output. We prefer to buy Panasonic or other "big names" in rechargeable batteries because of the safety considerations. These Panasonic AA cells have an output of 2100 mAh which puts them in the middle range of AA cell output.
On delivery I found these pre-charged batteries had around a 90% charge and my advice is to use them and run them down before putting them into your charger - they are designed with that in mind. These batteries charge quickly although that depends to an extent on the charger you use - you can get Panasonic's own models. Once charged, my experience is that the cells maintain their charge for over a year unlike early versions which discharged in a couple weeks. The cells look and feel well made and the fit into all our devices is fine. There's nothing not to like about these Panasonic Infinium cells. Recommended.
I'm already up to 7 packs of these Panasonic Infinium bought over the last 18 months. With this order I have moved up from AAA's to AA's for new powered Salt-n-Pepper grinders. I can vouch from experience, these batteries will perform as described.
The ability of a battery to retain the vast majority of its charge for long periods is a virtue that Alkaline batteries have. The ability to be recharged countless times is a virtue that NiCad, NiMH and Lithium Ion batteries have. Hybrid batteries like these Panasonic 'Infinium' have both virtues - Rechargeable and long charge retention times (claimed as 85% charge after 365 days - who am I to argue). Think of it as "Having your cake and eating it."
Add a great product to a consistently quick delivery service at a very reasonable price and it all adds up to a 5 star service. There's only one tiny downside with these 'hybrid' batteries and that's the slightly lower capacity, than for example a NiMH battery. In the case of these AA batteries the capacity is 2100 mAh. No great shakes - I can live with that.
Buy these batteries you won't be disappointed. I'll keep buying them while they keep performing ;o)
Pre charged in factory. Easy to unpack. Possibly one of the best rechargeable batteries around. I would certainly purchase these again. Ideal for camera's that eat up batteries. All of my Energiser batteries are dead, the Gp branded ones seem very poor on holding their charge. Which leaves those at 7 Day Shop and Panasonic. I have both, but give the Panasonic ones top marks (just). They are a good investment and will not let you down, in my opinion.
I find the latest low self discharge Nimh which hold charge for many weeks much easier to live with as a major user of cameras and flashes, even though they lack the wallop of ordinary Nimh which are now approaching 3000mAh. These are performing well but I take one star away because the plastic wrapping around one of the 4 cells I ordered has peeled off and I had to replace it with shrink wrap or there was a danger of shorting.
Had bought some years ago, they had lasted 7 years, sadly I had lost them:( Had great difficulty finding replacement. Thank you Amazon. The batteries: - charge quickly - last very long (even in high tech equipment) - don't go flat when not in use - great price - one of a kind (checked other brands; they don't compare)