| 摘要 |
A battery-powered electrical device comprising a switchable voltage drain (3,5) and a rechargeable battery (1), and further comprising means for measuring the voltage V across the terminals of the battery (1) as a function of cumulative discharge time t, and for determining the cumulative discharge time tp corresponding to the attainment of the local extremum of least magnitude in the derivative dV/dt. In a particular embodiment, the device contains means for interrupting the voltage drain (3,5) upon expiry of a cumulative discharge time te=ntp, whereby n is a fixed, pre-selected real number. In addition, it is possible to calculate and display the remaining discharge time trem=moto-t, where mo is a fixed, pre-selected real number. The values of n and mo will generally be chosen to lie in the range 1.2-6.
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