10.1.1. Voltage measurement

Measuring devices

Control lamp and indicator of tension

Voltage measurement
Tension can be determined by a simple control lamp or the indicator of tension. In this case presence of tension is distinguished only. To measure its size it is necessary to connect the voltmeter.

Cables of the measuring device need to be connected to the consumer in parallel. At the same time the red cable of the measuring device is connected to the cable going to a positive pole of the rechargeable battery, a black cable to a negative wire or "mass" of the car, for example, to the engine.

Example of measurement: if the engine is badly started as the starter twists too slowly, then it is expedient to check tension of the rechargeable battery in operating time of a starter. For this purpose to connect a red cable () the voltmeter to a positive pole of the battery, and a black cable (-) to the mass of the car. Then, with assistance to include a starter and to measure tension. If voltage below 10 V (at a temperature of battery of 20 °C), it is necessary to check the rechargeable battery or to charge it.