There has been some comments regarding the number of charge cycle's and how much the battery should be allowed to discharge before re charging. However batteries from manufacturers such as Pure Energy are designed to be charged 100's of times but only with a charger designed fot these RAM batteries.

Normal alkaline batteries should never be recharged and are not designed to do so.

AA and AAA batteries are probably the most common battery sizes for consumers today. The challenge is there are so many different kinds of AA and AAA batteries, nickel metal hydride batteries, lithium batteries, lithium ion batteries, alkaline batteries, Ultra low discharge NIMH and even RAM rechargable alkaline each of them have their strengths and weaknesses for use in today's modern electronic equipment.

The average household uses 21 batteries a year.  What we will try to do it here is to explain some of the advantages and drawbacks of each different battery type and explain what the recommended ideal battery type for different applications might be so that you can make an informed decision about which batteries to use for all of your electronic equipment.

• alkaline batteries - if you don't use a lot of batteries and the devices that you do have are not gobbling up your alkalines - use them, you can't beat them for convenience and initial cost. Check them occasionally as they can leak if left well past their expiry date shown on the can.

• lithium batteries - if you need batteries that last for years or are fantastic in extreme temperatures, this is the ticket. They are not rechargeable but there are some applications where these really are the best batteries for the job, especially in smoke detectors for example (PP3 version). They do last several times longer than alkaline, up to seven so the ads go... and also perform well in high drain application (AA and AAA) such as digital cameras. They also have a longer shelf life than alkaline.

•nickel metal hydride (NIMH) batteries - . Environmentally friendly rechargeable batteries. If you use your device a lot and over a short period of time - say days or weeks, the higher the mAh rating on your NiMH high capacity battery the longer it will last per charge (it will also take longer to charge though). Now available in a Ultra Low Self Discharge (ULSD) -my personal favourite also known as ready to use N1MH batteries -. When you buy them they are ready to use. This is a better choice for general purpose use if you use devices that are high drain infrequently (it is high drain if it uses alkaline batteries fast).- e.g.- I have a Olympus digital camera, I like it but don't use it a lot. I'll take a few pictures and then leave it in a drawer for weeks on end. This is the perfect application for the ULSD type of NiMH batteries. The self discharge issue with nimh batteries is probably their biggest weakness loosing approx. 30% of their charge/month (over a 3 month period they are often unusable) This newer type of battery addresses this problem to great effect. If you have not tried them you really need to.

• alkaline (RAM) batteries - these are a modified alkaline battery specifically developed to make them rechargeable using a smart charger developed by the manufacturer for use with these batteries. They must NOT be used with other chargers and are not suitable for high drain applications. As they are 1.5v as opposed to 1.2 volt nickel metal hydride they are useful where equipment may be voltage sensative. These batteries do however have some recharging issues

• nickel cadmium batteries - in some cases these batteries are still a good choice - we don't offer them on our site - but for high temperature applications or some commercial applications these are actually better than NiMH. Not environmentally friendly though .

• Why use rechargeable batteries at all- This saves energy because the energy needed to manufacture a battery is on average 50 times greater than the energy it gives out. Whilst to recharge a NIMH rechargeable battery uses approx. 1 ½ times (depending upon how fast the re-charge cycle takes-typically 5 to 10 hours ). However, rechargeable batteries are not suitable for smoke alarms as they tend to run out suddenly, preventing the alarm from warning when battery power is low.

You probably mean to ask: What is the self discharge rate of a NiMH battery? The rate of self discharge for any battery depends on the temperature at which they are stored. Stored at 70 degrees F (20 C) NiMH batteries will lose up to 40% of their charge within a month. If they are stored at a higher temperature, they will self discharge at an even higher rate. Stored at a lower temperature they self discharge at a lower rate. Think of a NIMH battery as a bucket of water with a small hole in the bottom, if you don’t use the water up before it is empty it will be empty anyway over a period of time. Ultra Low Self Discharge NIMH batteries overcome this problem to a great extent.

Typically "100’s" and up to 1000 with the very latest technology. The reason we can be more specific is because this is a more complex question to answer than it at first might seem. The number of times a battery can be recharged depends on how the battery is used ( how deep the discharge before recharging for example). An analogy that is sometimes used is to compare a rechargeable battery to a loaf of bread. Suppose someone asked, how many slices can be cut from a loaf of unsliced bread? The answer, of course, depends on how thick or thin the bread is sliced. If the slices are very thin it can be cut into more slices. The same is true for recharging a battery. Every time a rechargeable battery goes through a charge and discharge cycle it loses a tiny bit of capacity.

If the battery is completely discharged before it is recharged, that takes a bigger "slice" of the battery's capacity, if it is only partially discharged a before recharging, it uses up a smaller "slice". A NiMH battery can be charged and discharged hundreds of times, but whether that means 200 times or 1000 times has a lot to do with how big of a "slice" you take each time.

One of the problems with terms like these is that the amount of time it takes to charge a battery is dependent on the capacity of the battery being charged. A charger that can charge a standard capacity AAA MIMH battery (1300 mAh) in just five hour might take thirteen hours to charge a high capacity NiMH (2700 mAh) battery.

It's best to ignore such terms and use the charge time as a relative indication, unless the charge time is quoted against a specific battery capacity.