Next find the positive contact and the negative contact, marked by (-) and (+). Place your black lead on the negative (-) contact, and the red positive lead on the positive (+) contact. If your battery is not marked, then test two contacts at a time until you get a positive DC voltage on your meter, you have found the positive and negative contacts. You should read around, or even a little bit more voltage than the label states for a fully charged battery. If you find your voltage is too low, and the battery is fully charged, then the battery is bad. I would recommend taking the battery with you when you go to the cell phone store for a new one, and let them test it for a second opinion.

If you are getting good voltage, but the battery still will not power the phone, then maybe your problem lies with amperage. Even though voltage is good, if you do not have good amperage (current), then the battery will not power the phone.

If you know, or can find the correct milliamps of the battery, then an amp meter would tell you if your battery is good.

If you do not have an amp meter, or cannot find the correct milliamps of your battery, then I would suggest taking your battery to a cell phone store for testing.

If you are having problems keeping your battery charged, then the life of the battery is probably over. A lithium ion battery (rechargeable) will only last for so many charge cycles. Of course your charger could be failing also. 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 bad, and your battery is probably ok.

Cell phone batteries can be tricky to troubleshoot, so if you're in doubt with any of these tests, just take your phone in for a quick diagnostic at your cell phone dealer, it's usually free. 

                                                    See more how-to articles