Low self-discharge NiMH battery

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The low self-discharge nickel-metal hydride battery (LSD NiMH) was introduced in November 2005. It reduces self-discharge and, therefore, lengthens shelf life compared to normal NiMH batteries. By using a new separator that is saturated with deionized water, manufacturers claim the batteries retain 70 to 85% of their capacity after one year when stored at 20 °C (68 °F), while standard NiMH batteries may lose half their charge in this time period. Low self-discharge cells are marketed as "ready-to-use" or "pre-charged" rechargeables.

Low self-discharge NiMH batteries are good for photography and other high energy requirement applications. Due to the low self-discharge, they are also suitable for long-term intermittent or low-current uses; they might last up to a year between charges, much better than ordinary NiMH batteries. They can therefore also be used for electrical clocks, remote controls, etc.

Aside from their longer shelf life, and moderately higher prices, they are otherwise similar to normal NiMH batteries of equivalent capacity and can be charged with normal NiMH chargers. However they are generally available at lower capacities than the highest capacity of normal NiMH batteries.

[edit] Charge retention

It is generally claimed that low self-discharge NiMH batteries retain 90% of their charge after six months, 85% after a year and 70% after two years, when stored at 20 °C (68 °F).

[edit] Other benefits

Low self-discharge NiMH batteries typically have a significantly lower internal resistance than traditional NiMH batteries. This has a number of desirable effects especially for high-drain applications:

• Voltage is more stable (less load- and capacity-dependent). This can have a beneficial effect on runtime in electronic devices, which typically have a cut-off voltage per battery that is not much lower than NiMH's nominal voltage. (However, this can also cause some devices with battery status indicators to overestimate the remaining capacity of a nearly drained cell.)
• Reduced heat buildup when the battery is quickly charged or discharged
• Higher efficiency