TREE

With a suitable load, the terminal voltage of a NiCd or lithium-ion battery is proportional to the amount of stored energy. This relationship, which is linear over a wide range, can be used to build a simple battery capacity meter. Circuit Image :   Voltage Tester for Model Batteries Circuit Image  This model battery tester has two functions: it provides a load for the battery, and at the same time it measures the terminal voltage. In addition, both functions can be switched on or off via a model remote-control receiver, to avoid draining the battery when it is not necessary to make a measurement. The load network, which consists of a BC517 Darlington transistor (T2) and load resistor R11 (15 Ω /5 W), is readily evident. When the load is active, the base of T1 lies practically at ground level. Consequently, T1 conducts and allows one of the LEDs to be illuminated. Circuit Diagram : Voltage Tester for Model Batteries Circuit Diagram The thoroughly familiar voltmeter circuit, whi...

Rechargeable batteries of 6V and 12V are used in a large number of applications. It is imperative that these are maintained properly to get maximum life out of them. Further, their permissible number of charge-discharge cycles must be fully utilised. Here is a circuit that gives a visual as well as an audible alarm if the battery voltage is higher or lower than acceptable limits, so that corrective action can be taken. Circuit and working As shown in Fig. 1, the circuit is built around dual-operational amplifier LM358 (IC1), hex inverting Schmitt trigger 74HC14 (IC2) and a few other components. The circuit can be divided into two parts—the input unit built around two operational amplifiers (op amps) in IC1 working as comparators, and audio alarm unit built around two RC oscillators and a transistor. Voltage from the battery under test (BUT) is applied to connector CON1. It is divided by five by R1 and R2 for comparison with the threshold levels. the power supply of the circuit is limit...