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voltage gauge reads lower than what it really is
The battery voltage of the car is lower than what it really is , the indicator light of the instrument panel is not on, and the indicator light of the instrument panel is not on. First, check the power supply fuse of the instrument panel, and replace it if it is blown. The lamp on the instrument panel is damaged and needs to be replaced in time; If the power supply line of the instrument panel is broken, open circuit or short circuit will occur, which will also cause the instrument panel of the vehicle to be not lit;If the power supply fuse of the instrument panel of the car is broken, the power supply will not be available, and the instrument panel will not light up.
The battery can not be judged by voltage. Some bad batteries have rotten positive plates. The measured voltage is still 12V. The voltage measured by the electric meter is virtual voltage, not real voltage. We know that the internal resistance of a new battery or a fully charged battery is very small, and the internal resistance of a single cell of a battery above 50 ampere hour is generally below 0.0015 ohm.
The automobile battery is generally composed of 6 single cells connected in series, and the total internal resistance is mostly below 0.01 Ω. The discharged battery has a large internal resistance. Therefore, the most reliable detection method is to determine the amount of storage battery by checking the voltage value at both ends of the pole when the battery is discharged with large current.
The specific method is to use a device called high efficiency discharge meter to measure. The high rate discharge meter is composed of a spring (resistance for discharge) wound by a thick alloy wire and a voltmeter. The resistance value of the spring is 0.06 ohm. If it is connected in parallel to a 12V battery, if the internal resistance of the battery is extremely small, it should generate a current of about 200A. At this time, if the reading of the voltmeter connected in parallel to this resistance is 10V or above, it means that the power is sufficient.If it is 9.5v, it means that the electricity is not small, but it is not enough; The lower the reading is, the less power is stored. If the reading of the voltmeter is 8.4v or less, it indicates a serious power loss and should be charged in time. If the reading of the voltmeter is 0V, it indicates that the battery has been damaged and the charging may not be able to recover.
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