A battery charge level indicator

Proposed is a circuit designed to indicate the state of charge of a rechargeable battery, the state of charge of the battery being determined by integration of the current flowing in the load circuit. Various correction factors are applied to allow, for instance, for turn-on current surge, temperature, offset and self-discharge effects, thus giving a reproducibly accurate state-of-charge determination. A battery of this kind is particularly suitable for use as a power pack for electrically powered tools. Appropriately designed terminals make it possible to employ a universal battery charger and to use different types of battery for different electric tools.