How Do You Tell If a Battery Is Dead? A Quick & Easy Guide

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Check the charge in your alkaline, car, & phone batteries
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Discovering that a battery you need to power an important device has a low charge or is completely dead is a frustrating, but universal experience. This article will help you test your alkaline batteries ( with and without a multimeter ), car battery , and iPhone or Android battery at home, so you can determine if they're still good or need to be replaced.

How to Test If a Battery Is Good

  • Alkaline battery : Use the drop test, a battery tester, a load test, or a multimeter.
  • Car battery : Use a multimeter or have the battery tested for free by an auto parts store or repair shop.
  • Phone battery : Check your iPhone battery's health under Settings, use a 3rd party app like AccuBattery for Android, or have the battery tested at a phone store.
Section 1 of 4:

Testing Alkaline Batteries Without a Multimeter

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  1. A drop test won't tell you if an alkaline battery is dead, but it can help you distinguish new batteries from old ones. That way, you know which ones are most likely to work the longest. Perform this test by holding the battery 2–3 in (5.1–7.6 cm) above a hard, flat surface like a metal table or marble countertop. Position it vertically with the flat end facing down, then drop it. A fresh battery will plop down without bouncing. An older battery will bounce up several times before falling over. [1]
    • For AA, AAA, C, and D batteries, hold the battery so the positive end faces up.
    • For a 9V battery, hold it so both nodes face up and the flat end faces down.
    • A wooden surface is not the best choice for this test. Wood absorbs more energy, and items don’t bounce as well on it.
  2. Universal battery testers are easier to use than a multimeter, though they don't provide much information besides voltage. The tester contains a slide that moves back and forth to adjust to different battery sizes. Open the slide and insert an AA, AAA, C, or D battery into the slot with the positive terminal touching the slide. Then check the display for the voltage reading. Green means it has a charge, yellow means it has a low charge, and red means it's dead. [2]
    • Some battery testers come with a separate port that you can touch the battery against to get a voltage reading. If you're testing a 9V battery, check if your tester has this feature.
    • Some meters can also test lithium ion batteries if they’re shaped like standard alkaline batteries, but not if they’re irregularly shaped.
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  3. Running a load test requires using a voltmeter or multimeter and a resistor to measure the alkaline battery's power when it's in use. To start the test, switch the voltmeter to direct current (DC) voltage. Then hold the black probe of the voltmeter to the negative end of the battery and the red probe to the positive end. Turn the voltmeter on and take a voltage reading without a load. Next, clip the terminals at either end of a 100-ohm resistor to the voltmeter probes with alligator clips . Turn the voltmeter on again and get a voltage reading with a load. [3]
    • Compare the two measurements. On a load test, the battery should drop only slightly below its normal voltage without a load. If it drops below the listed voltage on the battery (e.g., below 1.5V on an AA battery), however, that means the battery is dead.
    • For example, if you tested a fresh 1.5V battery with just the voltmeter, you might get a reading of 1.593V. That's a normal reading. After connecting the resistor, you might get a reading of 1.547V. That's only a small drop, which is a good thing and means the battery still has a healthy charge. [4]
    • This particular test won't work on a lithium ion battery because multimeters don't have load test settings for their voltages.
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Section 2 of 4:

Testing Alkaline Batteries With a Multimeter

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  1. To obtain an exact measurement of a battery’s charge, use a multimeter . Start by finding the positive and negative terminals on the battery you’re measuring. These are marked on the battery with a "+" and a "-", respectively. [5]
    • On AA, AAA, C, and D batteries, the negative terminal is the flat side and the positive terminal is a protrusion on the opposite end. On a 9V, the smaller, rounded terminal is positive and the larger, hexagonal terminal is negative.
    • This method also works for rechargeable lithium batteries. Lithium batteries come in many shapes, so look for the "+" and "-" markings on the battery to determine its positive and negative terminals.
  2. Turn the knob on the front of your multimeter to direct current (DC) and pick a maximum voltage level before taking a reading. On most multimeters, the lowest setting is 20V. This is high enough for all common alkaline batteries. [6]
  3. On a multimeter, the red lead is positive and the black lead is negative. Hold the positive lead to the positive battery terminal and the negative lead to the negative terminal. [7]
    • If you mix up the leads, it won’t damage the battery, but the reading will show a negative value rather than a positive one.
    • Common household batteries won’t shock you during this test, so don’t worry.
  4. The meter will produce a reading within a few seconds. Use this reading to tell if the battery is fresh or not. [8]
    • Fully-charged AA, AAA, C, and D batteries have a charge of 1.5 volts. A 9V has 9 volts. If the charge is more than 1 volt below where it should be, replace the battery.
    • A normal charge for lithium ion batteries is 3.7 volts, but this could vary. Check with the manufacturer for the full charge.
    • A 3.7-volt lithium battery usually stops working at 3.4 volts, so recharge or replace your battery if it's approaching this level.
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Section 3 of 4:

Testing a Car Battery

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  1. You don't need a tester to see your battery is dead. When you turn the key or press the start button, you won't get any cranking at all from your engine. Your headlights also won't come on, or if they do, they will be very weak. [9]
    • If your battery is almost dead, the car may crank some but won't actually start.
  2. Turning the car off before testing the battery is safer and will make the process easier. If you're not sure where your battery is, check your owner's manual. Lift the hood and look for a black rectangular box marked with positive (red) and negative (black) terminals. [10]
    • Your battery may be covered with a plastic hood. If it is, refer to your owner's manual. You'll likely need to loosen a few screws to take it off.
  3. Set the multimeter to DC voltage. Place the end of the black probe on the negative terminal and the end of the red probe on the positive terminal. Watch the readout on the multimeter. [11]
    • If your battery is reading at or above 12.45 volts, your battery is still in good shape, and any problems you may be having are likely caused by something else.
    • If your battery is reading below that, it won't consistently start your car, and you'll likely need to get a new one.
    • A car battery tester will do the same job. All you need to do is place the black clip on the negative terminal and the red clip on the positive terminal.
  4. Auto technician Jason Shackelford recommends testing your car battery at an auto parts store or a repair shop, saying, "Home diagnosis is rather difficult and not very accurate." [12] These places typically test your battery at no charge.
    • Most auto parts stores will even put in a new battery for you if you don't know how to do it.
    • If your battery is dead, jumpstart it or charge it to get it to the store.
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Section 4 of 4:

Testing an iPhone or Android Battery

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  1. Open Settings, tap Battery, then tap Battery Health & Charging. Look at the Battery Level graph for the past 24 hours to see the battery's overall health and periods when it went into Low Power Mode. Then check the Insights and suggestions section to see what settings Apple recommends changing to improve the battery's performance. [13]
  2. Download an app designed to test the health of your battery, such as AccuBattery . Open the app and follow the instructions on the screen to set it up. Then use your phone as you normally would for at least 24 hours. After 24 hours, open the app to view information on the health of your battery. You'll get more accurate information after using the app for weeks or even months. [14]
    • You can also use third-party apps, such as Coconut Battery, to test an iPhone, but you'll need to plug it into a Mac to do it. [15]
  3. Cell phone retailers can perform a comprehensive test on your phone battery and check its performance. For iPhones, an Apple Store is your best option, as it will have everything you need to get your battery checked and serviced. [16] For Androids, visit a store that sells smartphones and batteries.
    • These stores can also replace your battery if it's gone bad. They may need to wait for the part to arrive if it isn't in stock.
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Community Q&A

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  • Question
    How can I test a 9-volt battery?
    Community Answer
    If you have a multimeter, you can try hooking it up to it. If not, a battery tester is probably the best solution.
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    Not Helpful 9 Helpful 7
  • Question
    Is it possible to test a watch battery, like the ones that look like a coin, with a voltmeter?
    Community Answer
    Yes. Use a multimeter set on DCV, place the red (positive) lead on the + side of the watch battery. Place the black (negative lead on the other side of the coin. You are looking for a reading at 3v. If the reading is 3 the battery should be good. If not, replace it.
    Thanks! We're glad this was helpful.
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  • Question
    Can I use the drop method on a carpet?
    Community Answer
    The natural "springiness" of a carpet would make it difficult to interpret the results of such a test. So in most cases it probably wouldn't work.
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      Warnings

      • Avoid tampering with batteries. Although it's unlikely, you may short out the battery. You'll know if that happens because the battery will heat up. If that occurs, immediately take the battery outside and place it on a non-flammable surface like a concrete driveway. Do not retrieve it until it has cooled down.
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      References

      1. ↑ https://www.princeton.edu/news/2015/03/30/battery-bounce-test-often-bounces-target
      2. ↑ https://youtu.be/n4mKFZT92is?si=cMOCPS89Y7yFCsX_&t=32
      3. ↑ https://youtu.be/JjElWj0fFX4?si=ZyKTWhdh6ZhMQS8-&t=42
      4. ↑ https://youtu.be/JjElWj0fFX4?si=ldWrTS-k4AuMlPww&t=77
      5. ↑ https://sciencing.com/test-lithium-ion-batteries-6886166.html
      6. ↑ https://sciencing.com/test-9volt-battery-8129945.html
      7. ↑ https://sciencing.com/test-9volt-battery-8129945.html
      8. ↑ https://youtu.be/okNXOYCsMe4?t=173
      9. ↑ https://www.kbb.com/car-advice/dead-battery/
      1. ↑ https://www.digitaltrends.com/cars/how-to-test-a-car-battery/
      2. ↑ https://www.digitaltrends.com/cars/how-to-test-a-car-battery/
      3. ↑ Jason Shackelford. Auto Technician. Expert Interview
      4. ↑ https://support.apple.com/guide/iphone/check-battery-health-and-usage-iphd453d043a/ios
      5. ↑ https://www.tomsguide.com/how-to/how-to-check-android-battery-health
      6. ↑ https://www.cnet.com/how-to/iphone-battery-health-how-to-check-it-on-your-own/
      7. ↑ https://www.apple.com/batteries/service-and-recycling/

      About This Article

      Article Summary X

      To test your battery, start by holding it flat-side down an inch or 2 above a table. Then, drop the battery. If it bounces and falls over, the battery is probably dead. If it doesn’t bounce, it probably still has some charge left. Keep in mind this method only works with AA or AAA batteries. Alternatively, use a multimeter to test your battery by turning the knob to 20 on the “DCV” or “V” side. Touch the red probe to the battery’s positive terminal and the black probe to its negative terminal. You should have a working battery if the multimeter reading is close to the voltage written on the battery. However, if the reading is lower, it’s probably dead. For more tips, including how to test a 9-volt battery, read on!

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