Abstract: The method and the apparatus for detecting a deteriorating condition in a bank of standby batteries includes injecting an audio frequency current into one of the battery buses or cables, detecting an audio frequency current signal, matched to the injected audio frequency current signal, that is carried by the battery bus and detecting a voltage drop, at the audio frequency, across the bank of standby batteries. In one embodiment, current transformers are utilized in connection with an oscillator (to inject the AF current signal) and detection circuits (comparators and operational amplifiers) are utilized to generate a representative current signal and a representative voltage signal. The device detects when the standby batteries are operating in a normal, stable condition, that is, when the bank is neither being recharged nor is discharging DC power to the load.

Abstract: The non-intrusive open battery bank detector circuit senses an alternating current component of the DC trickle charge carried by one of a pair of cables connected between the battery charger and the bank of batteries. The detector circuit includes a sensor that is disposed adjacent, but not physically around or electrically connected to, one of the cables. The sensor detects magnetic fields established around the cable. The output of the sensor is connected to a low-pass filter which passes signals consisting primarily of 60 and 120 hertz components. A pre-amplifier amplifies the passed signals. A ripple filter smoothes the pre-amplified signals and a comparator determines whether the smoothed signal is greater than a reference signal thereby signifying the presence of a DC trickle charge on the cable next to the sensor. A transistor switch has its control input connected to the output of the comparator and is triggered on when the output of the comparator is high.

Abstract: This invention relates to improved weighing apparatus for fork lifts comprising a weigh bridge supported at each end thereof by load cells. The weigh bridge and load cells are built into the fork so that the overall height of the fork is kept to a minimum.