A D battery, also known as a D cell or IEC R20, is a standardized size of a dry cell. A D battery is cylindrical with an electrical contact at either end. The positive end has a nub or bump, while the negative end is flat. D rechargeable batteries are ideal for use in high current drain applications, such as large flashlights, radio receivers and transmitters, and other devices that need an extended running time. A D cell may be either rechargeable or non-rechargeable/primary.
The capacity of D Rechargeable Batteries
The first D cell came into being in 1898 and it was widely known as flashlight batteries. A battery’s capacity is based on its cell chemistry and current draw. Some alkaline D cell performance is rated as approximately 20,000 mAh at 25 mA draw and about 10,000 mAh at 500 mA draw. The effect is generally less noticeable in cells with NiMH chemistry and scarcely at all with NiCd. Several common size D rechargeable cells are sub-C cells in a D-sized holder.
D batteries come with a nominal diameter of 33.2 ± 1 millimetres (1.3 inches) and their overall length is 61.5 millimetres (2.42 inches).
How to Improve the Lifespan of D Rechargeable Batteries?
Apart from the capacity, several other factors determine the longevity of a battery. While rechargeable batteries come with the natural advantage of longer life than their non-rechargeable counterparts, you have to take good care of them. As such, the temperature is the important factor that affects the life of a battery.
The migration rate of a rechargeable battery in the electrolyte and electrode sheets is closely related to temperature. Hence any fluctuation in temperature will drastically affect the technical performance of a rechargeable battery.
This is another factor that affects the longevity of a battery. Under normal circumstances, long-term storage at low temperatures is likely to destroy the internal chemical substances of the battery because the battery contains liquid inside. Therefore, a storage temperature not lower than -20°C is recommended. Similarly, too high a temperature will also cause damage and hence the battery cannot reach its rated capacity. So, you must store the battery at a temperature ranging of -20℃～+65℃.
The ideal charging temperature of a rechargeable battery is between 0°C and 45°C. Anything above or below this will affect the longevity of your battery.
Normally, the discharge temperature of a rechargeable battery is between -20°C and 65°C. The battery packs are generally discharged before they leave the factory to prevent short circuits due to shock and other such hazards during transportation. So, a new battery is not charged or might contain about 20% of electricity.
It should also be noted that a new battery or a battery that is not used for a long time may not be fully activated in a single charge cycle. It might need two or three cycles of low current (0.1C) charge and discharge treatment before it can reach the normal capacity. That is why you should store batteries that will not be used for a long time in a charged state. The best way is to store them after pre-charging 50% to 100% of the power. Furthermore, it is better to charge the battery once every three months to restore the saturated capacity.
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