Battery repair - how to measure battery quality with a multimeter
1. A multimeter can only measure the virtual voltage of the battery, and whether the battery is turned on can be known by charging the battery. If the internal resistance of the battery is large or there is a break, the current will be very small. If the current is normal but the voltage is low (for example: below 12V and cannot be charged), there may be a short circuit.
2. It is very meaningful to measure the battery voltage while adding a load to the battery.
For example: connect a 12V100W bulb, and measure the battery voltage at the same time, if it is above 12V, it is normal. If the light is bright at first and gradually dims, the battery is dead and needs to be recharged.
If the light is on but the voltage is only about 9V and can continue, it means there is a short circuit. If the load voltage is connected to 0, it means that the internal resistance of the battery is very large or there is a broken grid.
The large internal resistance of the battery is generally caused by severe vulcanization.
