Follow these instructions to test a cell phone battery.
Cell Battery Test
Step 1- Remove the battery.
Turn off the phone and remove the battery from the cell phone compartment.
Step 2- Locate the battery voltage.
Check the label to see what the voltage should be. Most cell phone batteries produce approximately 3.4 to 4.5 volts dc.
Step 3- Locate the negative and positive power contacts.
Find the metal contacts on the edge or bottom of the battery, most brands will have 3 contacts. Find the positive contact and the negative contact, marked by (-) and (+). If the battery is not marked, test two contacts at a time with a multimeter until you get a positive DC voltage meter reading. These are your positive and negative contacts.
Step 4- Test the battery voltage.
Place your black lead on the negative (-) contact, and the red lead on the positive (+) contact while in the VDC setting. The measurement should be a bit higher voltage than the label states for a fully charged battery. If you find the voltage is too low, and the battery is fully charged, then the battery is going bad.
Step 5- Test for correct amperage.
Test the battery with a load light. Touch the load light probes onto the negative and positive contacts of the battery and it should illuminate. An ammeter can also be used to check the amperage of the cell phone battery.
Step 6- Test the battery charger.
If you have more than one charger, try hooking your phone up to the other charge source and see what happens. If your battery charges on the other charger, then the original charger is faulty.
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