Abstract: The present invention relates to a method for operating a battery charger, and a battery charger. The method comprising the steps of determining a capacity of the battery, determining an initial charging current, apply the calculated initial charging current as a charging current to the battery, determining the voltage change with time ?V/?t for the voltage over the battery, adjusting the charging current based on the ?V/?t.

Abstract: The present invention relates to a method for operating a battery charger, and a battery charger. The method comprising the steps of determining a capacity of the battery, determining an initial charging current, apply the calculated initial charging current as a charging current to the battery, determining the voltage change with time ?V/?t for the voltage over the battery, adjusting the charging current based on the ?V/?t.

Abstract: A method for measuring a capacitance using a capacitance meter. The capacitance meter includes an AC power source with a controllable frequency which is fed to a capacitor to measure its capacitance. A first measurement of the capacitance is performed by the capacitance meter using a first frequency. When the first measurement of the capacitance indicates the capacitance is below a threshold capacitance a lower capacitance measurement is performed in the capacitance meter, using a second measurement of the capacitance using a second frequency. When the first measurement of the capacitance indicates the capacitance is above a threshold capacitance, a higher capacitance measurement is performed in the capacitance meter, using a second measurement of the capacitance using a third frequency, the third frequency being lower than the second frequency.

Abstract: A capacitance meter including an AC source providing a measurement voltage with a measurement frequency to a capacitor. A current sensor is arranged to measure a current going to or from the capacitance meter. A voltage sensor is arranged to measure a voltage over the capacitor. A capacitance calculation unit is arranged to calculate, using a controller, a capacitance of the capacitor using a measured current from the current sensor, a measured voltage from the voltage sensor and the measurement frequency. The capacitance meter is arranged to obtain measurements using the current sensor and the voltage sensor during a measurement duration. The measurement frequency and the measurement duration are selected such that the measurement duration equals a multiple of the period of the measurement frequency, and the measurement duration equals a multiple of the period of a mains electricity.

Abstract: A method for measuring a capacitance using a capacitance meter. The capacitance meter includes an AC power source with a controllable frequency which is fed to a capacitor to measure its capacitance. A first measurement of the capacitance is performed by the capacitance meter using a first frequency. When the first measurement of the capacitance indicates the capacitance is below a threshold capacitance a lower capacitance measurement is performed in the capacitance meter, using a second measurement of the capacitance using a second frequency. When the first measurement of the capacitance indicates the capacitance is above a threshold capacitance, a higher capacitance measurement is performed in the capacitance meter, using a second measurement of the capacitance using a third frequency, the third frequency being lower than the second frequency.

Abstract: A capacitance meter including an AC source providing a measurement voltage with a measurement frequency to a capacitor. A current sensor is arranged to measure a current going to or from the capacitance meter. A voltage sensor is arranged to measure a voltage over the capacitor. A capacitance calculation unit is arranged to calculate, using a controller, a capacitance of the capacitor using a measured current from the current sensor, a measured voltage from the voltage sensor and the measurement frequency. The capacitance meter is arranged to obtain measurements using the current sensor and the voltage sensor during a measurement duration. The measurement frequency and the measurement duration are selected such that the measurement duration equals a multiple of the period of the measurement frequency, and the measurement duration equals a multiple of the period of a mains electricity.

Abstract: A method and configuration from maintaining a constant of air to a protective helmet (4) from a fan (3) in a battery powered fresh air unit. The fan (3) is a radial fan with a filter (5) positioned on the suction side of the fan and is operated by a brushless continuous current motor (2). With the aid of signals from position sensors (30) in the motor (2), a control unit (12) can determine the speed of the fan (3). The control unit also detects the motor's power consumption and compares this and the speed with a characteristic curve for the motor (2) for a given flow from the fan, which is stored in a memory (14). In the event of any deviation, the control unit (12) regulates a change of the voltage supply to the motor (2) so that the deviation is reduced.

Abstract: A method and configuration from maintaining a constant of air to a protective helmet (4) from a fan (3) in a battery powered fresh air unit. The fan (3) is a radial fan with a filter (5) positioned on the suction side of the fan and is operated by a brushless continuous current motor (2). With the aid of signals from position sensors (30) in the motor (2), a control unit (12) can determine the speed of the fan (3). The control unit also detects the motor's power consumption and compares this and the speed with a characteristic curve for the motor (2) for a given flow from the fan, which is stored in a memory (14). In the event of any deviation, the control unit (12) regulates a change of the voltage supply to the motor (2) so that the deviation is reduced.