Using 1.2 V rechargeable batteries will have no effect on the use of the equipment. Indeed, an alkaline battery only benefits from 1.5 V voltage at the beginning of its discharge. Then, it drops constantly to well below 1.2 V. Finally, it drops to around 0.6 V. Most equipment will work happily on anything between 0.9 V and 1.5 V. Unlike alkaline batteries where the voltage drops quickly, rechargeable batteries offer a more constant voltage around 1.25 V throughout their period of use.That is why the latest rechargeable batteries will actually outperform alkaline batteries in equipment calling for a constant and high level of energy input, such as digital cameras, flashes, camcorders, computers, portable phones, CD players.

Rechargeable batteries (Ni-Cd, Ni-MH, Li-Ion) behave like a conventional battery. They consist of two electrodes immersed in a solution (electrolyte). Between each part is a fibre separator of paper or plastic.

Nickel-Cadmium (Ni-Cd) battery: The positive mass consists of Nickel Hydroxide and the negative mass of cadmium. The cadmium represents less than 20% of the rechargeable battery weight.

Nickel-Metal Hydride battery (Ni-MH): The positive electrode is a Nickel Hydroxide alloy and the negative electrode a Metal Hydride (MH).

Lithium Ion (Li-Ion) battery: This rechargeable battery offers high gravimetric and volumetric energy density. The no-load voltage is governed by a matching of electrodes for a Li2MnO2 / C combination, for instance, at a value of 3 V or 4 V, depending on the type of manganese diode being used. The anode consists of graphite. During recharging, the lithium is conducted in Ion form to the negative electrode. The process is reversed during discharge.

The Ni-Cd (Nickel-Cadmium) and Ni-MH (Nickel-Metal Hydride) batteries are used for camcorders, electronic toys (Game Boy, remote control cars), walkman, CD players, cassette players, radios, alarm clocks, tools, cameras, flashlights, walky-talkies, etc. They can be recharged up to 1,000 times.

Li-Ion (Lithium-Ion) batteries can be used in particular for portable telephones (GSM), digital camcorders, digital cameras and portable computers. They can be recharged between 500 and 1,000 times.

Rechargeable alkaline provide lower performance than ordinary alkaline batteries but can be recharged up to about 20 times. Ni-MH (Nickel-Metal Hydride) and Ni-Cd (Nickel-Cadmium) rechargeable batteries can be recharged up to 1,000 times. In addition, if a rechargeable alkaline battery is discharged entirely, there is a strong risk that it can no longer be used and will have to be disposed of.

Further, a rechargeable alkaline battery cannot be used for equipment using high current (digital cameras, flashes, etc.). It is unsuitable for fast charging and needs to be recharged in chargers designed specifically for the purpose. Otherwise, it will allow corrosive electrolyte to escape and damage the charger.

To summarize, the rechargeable alkaline battery represents a high cost for very limited use.

After using the battery, it needs to be discharged using a charger. If the battery has not been entirely emptied, the charge will not be complete and will set a new lower energy capacity. This is called the “memory effect”.

To avoid this, it is best always discharge the batteries entirely. It will help lengthen their life.

The memory effect does not occur with Nickel-Metal Hydride and Lithium Ion batteries.

Envie Ni-MH batteries are rechargeable up to 1000 times. This means you can use the batteries over and over again.

Envie Ni-MH batteries are designed for power intensive applications. Envie Ni-MH batteries maintain its high power during most of its usage. In other words, Envie Ni-MH batteries maintain a high and consistent voltage during most of its discharge. On the other hand, for alkaline batteries their voltage drops rapidly when used in a power intensive applications such as digital camera. This explains why you can only take 20-30 pictures using alkaline, while you can take up to 250 pictures using Envie Ni-MH. (For those who are a bit more technical, take a look at the discharge curve of the Envie AA 2000 Ni-MH battery).

Capacity counts. Ni-MH batteries are rated in “mAh”, acronym for “milli-ampere hours”. This number tells you how long the batteries can last under a certain power consumption. The higher the better for this number. For example, Envie Ni-MH AA batteries are rated at 2000mAh. This means its performance will be much better than the competition’s 1700mAh, 1800mAh or even 1900mAh.

“mAh”: Stands for milli-ampere hours. It measures the capacity of the batteries. For example, a 1000mAh capacity means that the batteries will last for 1 hour if subjected to a 1000mA discharge current.

“V”: Stands for voltage. It measure the power of the batteries. For Ni-MH batteries, they are 1.2V. For alkaline batteries, they are 1.5V.

“C”: “C” defines the rate at which a battery is charged or discharged. It is the capacity obtained from a new battery subjected to a constant-current discharge at room temperature. For example, draining a battery at 1C means to drain the capacity of a cell completely in one hour. Likewise, draining a battery at 0.2C means discharge a battery in 5 hours. For nickel-metal hydride cells, the rated capacity is normally determined at a discharge rate that fully depletes the cell in five hours, or 0.2C.

When charging rechargeable batteries, they do increase in temperature substantially due to internal resistance. Thus, the batteries may feel warm when the charge is completed. According to specification, most Ni-MH batteries, may heat up to 55° C during a rapid charge. This can certainly feel hot to some individuals.

When used with a overnight charger or a rapid charger with automatic termination, Ni-MH batteries can be left in the charger for an extended period of time without leakage, explosion, or deformation. However, do not store the batteries in the charger if it is not necessary. Always store charged batteries in a cool location.

You should discharge Ni-Cd cells before every fifth to tenth process of charging in order to avoid the feared memory effect. The memory effect has the consequence that the not used parts of the cell due to partially discharging are no longer in a position to receive and produce energy. Consequently, the operating times of their users (appliances) become shorter and shorter and the cells have to be recharged more frequently.