How to Test Cell Phone Battery with Multimeter (Step-by-Step Guide)

Cell phones have become a part of our daily routine. Like it or not, an average person usually spends five to six hours on their phone daily.

With that amount of daily use,  you probably drain the battery each day. So even if the battery indicator says it’s 80% charged, how much power does the device actually have?

This Step-by-Step Guide will show you how to test your cell phone battery with a multimeter, and a few common problems that a faulty battery can cause.

Step 1: Removing the Battery

Back in the day most cellphones actually had a removable back, however, that’s not the case with modern-day smartphones.

Removing the battery was as simple as popping out the back, and just reaching out to unplug the battery. 

If your phone has an easy way of removing the battery then great. But if your phone is sealed shut, you might need some extra tools to remove it safely.

Some common cellphones have the battery fixed with an adhesive (this is to keep the phone water protected) while this is a great feature it does make it almost impossible for the average user to remove their battery rather than a removal they need to purchase a whole new phone.

Common Models and Battery Removal

Samsung Galaxy S Series – adhesive fixed, very difficult to remove, can be done with specific tools

Iphones – use strong glue, can be very difficult to remove without an expert

We could provide you with a guide, but it all depends on your phone model, so please research this before continuing on as this guide assumes you have already removed the battery.

Once you have the battery out of your phone make sure to store it in a dry environment. 

Step 2: Checking Battery Label

Before proceeding with the testing, you need to check the label for the voltage. Most batteries are either 3.7V or 3.8V. After checking the labeling on the battery, adjust the multimeter setting to DC Volts. Some multimeters also use V for DC voltage.

If you are not sure if you chose the right setting, you can make sure by finding the straight line with 3 dots below it.

Black DT838 digital multimeter at an initial reading of 0.00v

AC voltage is accompanied by a curved line. Make sure to not use this setting since batteries always run on DC voltage.

Also, check if the battery indicates the amperage or mAh.

Step 3: Using the Multimeter

Place the battery so the terminals face you. The terminals are labeled with “+” and “-“.

The multimeter should consist of two probes. One black and one red probe.

Touch the tip of the red probe on the terminal labeled with “+“.

Touch the top of the black probe on the terminal labeled with ““.

Black DT838 digital multimeter set at an initial reading of 0.00v

Do this for a few seconds to make sure you have an accurate reading. Once the number stabilizes you should get the actual value.

Now, the reading displayed on the screen should indicate how much battery juice is in the battery.

If the reading is close to the battery label that you previously checked, that means the battery is fully charged. Compare that value with the battery indicator on your phone. (1)

Step 4: Test Again!

Before you come to a conclusion about whether your battery is dead or not, give the testing another go. If the readings are the same you’ve probably done the test right!

man charging phone

Step 5: The Results

After you made sure you’ve properly done the testing it’s time to know if you need a trip to your local mobile repair shop for a new battery.

If the multimeter reads over 3.0 volts, your battery is pretty much in pristine condition. 

If the multimeter reads between 2.2 and 2.9 volts, your battery is fine, but it means the chemicals inside aren’t as potent as they were and the battery is decaying over time. (2)

If the battery is showing a reading under 2.2 volts it’s time to throw it out and get a new one.

If the battery shows there’s power in it or it shows a high voltage reading, but there are still problems with it, you might want to check the amperage.

Repeat the testing the same way as before, but this time switch to the amperage setting on the multimeter. 

If the amperage displayed on the multimeter is significantly lower than the number on the battery label, the battery storage capacity is probably lowered which means it’s time to replace it.

How Do You Know if the Battery is Draining Fast?

A multimeter won’t help you determine if your battery is draining fast. It cannot actually measure the discharge. The multimeter will show you how much charge is left in the battery. That’s it.

How Do You Know if the Battery is Dead?

If the readings show 0, don’t give up yet. Grab your phone charger and plug it in for a while. Leave it for at least an hour before trying the test again.

If the numbers refuse to change, the battery is faulty. In this case, swapping out the battery is necessary since they are not repairable.

Take a look at some of our related articles below.




References
(1) phone – https://www.tomsguide.com/us/smartphones-best-battery-life,review-2857.html
(2) chemicals – https://ehs.mit.edu/chemical-safety-program/dangerous-highly-toxic-chemicals/

About Sam Orlovsky

b1d87d2ee85af3e51479df87928bdc88?s=90&d=mm&r=gI realized early on carpentry was a huge passion for me and I’ve stayed in the industry for over 20 years now. This gives me a unique ability to really be able to tell you what the best tools and recommendations are. I’m not only a carpenter but I also like machinery and anything to do with electrics. One of my career paths starting off was as an apprentice electrician so I also have a lot of experience with electrical products and anything related.