NI-CD FAQ

How NiCd Batteries are Unique

NiCad batteries are different from typical alkaline batteries or lead-acid batteries in several key ways. One of the main key differences is in cell voltage. A typical alkaline or lead-acid battery has a cell voltage of approximately 2V, which then steadily drops off as it is depleted. NiCad batteries are unique in that they will maintain a steady voltage of 1.2v per cell up until it is almost completely depleted. This causes the NiCad batteries to have the ability to deliver full power output up until the end of its discharge cycle. So, while they have a lower voltage per cell, they have a more powerful delivery throughout the entirety of the application. Some manufacturers make up the voltage difference by adding an extra cell to the battery pack. This allows for the voltage to be the same as the traditional type batteries, while still retaining the constant voltage that is so unique of NiCads. Another reason the NiCad batteries can deliver such high power output, is they have very low internal resistance. Because their internal resistance is so low, they are capable of discharging a lot of power very quickly, as well as accepting a lot of power very quickly. Having such a low internal resistance keeps the internal temperature low as well, allowing for quick charge and discharge times. This feature, combined with the constant voltage of the cells, allows them to put out a high amount of amperage, at a consistently higher voltage than comparable alkaline batteries.

Storing NiCd Batteries

When storing NiCad batteries, be sure to pick a cool, dry place. The temperature range for storing batteries is between −20 °C and 45 °C. When preparing to store NiCad batteries, be sure to discharge the batteries fairly deeply. The range in recommendations is between 40% and 0% charged when going into storage. NEVER short circuit a NiCad to drain as this causes excessive heat and can cause hydrogen gas to be released…AKA-Boom! The self-discharge rate for NiCad's is right around 10% at 20 °C, and rising up to 20% at higher temperatures. It is recommended not to store NiCads for an extended amount of time without occasionally using the batteries. Over long periods of storage the cadmium in the NiCad can form dendrites (thin, conductive crystals), which can bridge the gap between contacts and short out the cell. Once this happens, there is really nothing that can be done to fix it long term. The best way to prevent this from happening is frequent use.

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