What is the correct multimeter setting to test a car battery?
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The most accurate way to test a battery is with a multimeter. These digital devices are inexpensive and easy to use and are available at most auto parts stores. The multimeter can tell you about your battery's state of charge (SOC) and whether it's good or ready to be replaced. The key is to understand the various multimeter settings and what they mean for battery testing.
Here is a quick guide to the various multimeter settings and how they work:
Looking for car battery multimeter setting? Look no further! The voltage range for a car battery is between 15 and 20 volts. You can test your battery by setting your multimeter to the 20V DC range.
Be careful
Here you will encounter a potentially dangerous current, so be careful. First turn off the car and make sure the keys are out of the ignition. Then disconnect the negative cable from the battery with a wrench or socket. This is where you connect the black lead from your multimeter.
Connect the red test lead to the positive terminal of the car battery using another wrench or socket. Your multimeter should now be connected to both pins.
Set your multimeter to the correct scale
Make sure your multimeter is set to the correct voltage scale. Set it to 20V, a scale that can easily read both 12V and 6V batteries. If you have an analog multimeter, make sure the needle is set to zero before taking a reading - that way, any error on your multimeter will show up as an offset, not an offset plus a false reading.
Check battery with low load
The next step is to unplug all accessories in your car and check the battery voltage under low load. To do this, you need to find the positive and negative terminals on the battery. Then connect the red wire to the positive terminal and the black wire to the negative terminal.
If you see 12 volts or more on your display, this means that your car's charging system is working properly and there is no problem with the battery. If it reads anything below 12 volts, the problem is either with its charging system or with the battery itself. For example, a reading of 11 volts means your car battery has 50% charge left, while 10 volts means only 20% left.
Check battery with high load
When testing a battery under heavy load, switch the multimeter to the 20 volt DC range. If you don't have a high load tester, use a 100 watt bulb instead. A 100W lamp draws about 8 amps from the battery when on and about 1 amp when off.
The best way to test the battery with a light bulb is to remove it from your car's headlight or dome light socket. With the ignition off, connect one end of the bulb to ground and touch the other end of the bulb with a meter probe (Figure 2).
Have an assistant turn the ignition on while you look at the meter. If there is no voltage drop, then the battery and alternator are fine. If the voltage drop is more than 0.5 volts, you have a bad connection somewhere in any system.
DC vs. AC
This is probably what you are most familiar with. In this case, direct current is direct current, and alternating current is alternating current. When testing car batteries, you will always use DC voltage, so make sure it is set correctly!
Resistance (Ohm)
This parameter tells you how much resistance there is in the circuit. Ohms are the standard unit for measuring resistance, so this parameter is usually referred to as "Ohm". This parameter can help you measure resistance in wires and other components.
Voltage (V)
This setting allows you to measure the voltage of electricity between two points in a circuit. You can test this with a battery and alternator to make sure it's working properly. This will also be set to direct current (DC) when testing car batteries as this is how they work. (1)
Amperage (A)
Take a multimeter and find the current setting (A). You should see a small symbol that looks like a snake biting its tail - this is a symbol of current strength. (2)
Then locate the positive (+) and negative (-) battery terminals. They are usually marked in red and black respectively. If not, look for the little "+" and "-" symbols next to them.
Connect one of the multimeter leads to the positive terminal and the other to the negative terminal. The red tipped wire is connected to the positive terminal, and the black tipped wire is connected to the negative terminal.
Now look at the display on your multimeter: if it shows a number between 10 and 13 amps, your battery is in good condition! The numbers will be lower if you haven't ridden it recently, but they should come back after some running. Keep in mind that all batteries discharge over time, even if they are working fine now.
Take a look at some of our articles below.
- Multimeter battery test 9V
- How to read an analog multimeter
- How to check the generator with a multimeter
Recommendations
(1) electricity - https://www.eia.gov/energyexplained/electricity/
(2) snake bite - https://www.cdc.gov/niosh/topics/snakes/symptoms.html
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