How to check the battery and the current consumption when the car is stationary?
The battery is a key component of any car, van, truck, motorcycle, etc. It provides a store of electrical energy, which makes it possible to start the internal combustion engine, through a starter powered by electricity. This is why the battery should be taken care of, as it ensures that you will never encounter an unpleasant surprise on the road. Not being able to start the engine far from home is one of the worst bane of a driver. It sometimes happens that the vehicle draws excessive current at a standstill, due to a short circuit in the installation or other damage. This results in the engine no longer being able to start after a few days, or sometimes even a few hours. So let’s find out how to check the battery with a meter and determine whether it is being discharged while the car is stationary.
Check the condition and voltage of the battery
The first thing we should do is check that the battery is fully charged and in working order. So it’s worth removing it from the vehicle and connecting it to a charger for a few hours. However, if you don’t have an expensive and sophisticated device, you may have trouble determining when the battery is fully charged. So it’s worth checking its voltage with the simplest meter, which should be set to measure a DC voltage of more than 12 volts. If the battery shows a voltage in the region of 12.6 V to 12.8 V, it can be considered to be adequately charged. Just after disconnection from the charger, the voltage may temporarily be higher, even above 13 V, hence it is worth waiting several minutes before measuring.
Instead, we can check the condition of the battery using the vehicle’s installation itself. First, we install a fully charged one in the car. How to check the battery with a meter under load? It is very simple. We ask for help from another person, who will start the engine at the right moment. When the starter starts working, we read the reading of the voltmeter, which should be connected to the clamps at all times. If the voltage does not drop below 10 volts, it means that the battery is operational. A drop to 9 V already indicates some wear and tear, but you can still use such a battery.
We control power consumption and charging
The next step is to check the current consumption at a standstill. For this you will need a meter with an ammeter, the range of which will be at least up to 10 A (amperes). We disconnect the negative terminal from the battery, and then connect it to the battery post through the ammeter cables. At first, the draw will be high, so we leave the car for a long while to let all systems go to sleep. When at least several minutes have passed, we start checking the battery with a meter. We read the amperage value that appears on the display, it should not be higher than 50 mA (milliamps). When it is higher, it means that some component of the installation is constantly drawing current and therefore the battery is discharged. To determine where specifically the fault is, we can take out the fuses one by one and monitor when the current decreases.
Finally, it is still worth checking whether the battery charge is correct when the engine is running. How to check the alternator voltage regulator? It’s very simple. We reconnect the probes of the meter to the battery, setting it to measure the voltage. We start the engine and wait several seconds. During this time we should notice an increase in the voltage value, to at least 14.4 volts. Then we start electrical consumers, such as lights, blower or radio. We check for excessive voltage drop. At idle under load, the voltage may decrease slightly, but it should never drop below 13.8V. Then we increase the engine speed by adding gas. If at this point the value rises again in the vicinity of 14.4V, it can be considered that the voltage regulator and alternator are in good working order.
