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Mike, Mac Medic
Category: Mac
Satisfied Customers: 8527
Experience:  Over 20 years IT experience with Apple computers in publishing, marketing and design.
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My battery has been acting extremely oddly for the last

Customer Question

My battery has been acting extremely oddly for the last month or so. It drains very quickly at some points, and very slowly at others. Today, it reported a 20% power charge only a few hours after being unplugged, but when I plugged it in to charge it, it went back to registering at 74% charge. Do I need a new battery, or is something I'm not aware of draining the power?
JA: What OS X (Operating System, e.g. Sierra, El Capitan, Yosemite, etc.) or iOS are you running?
Customer: iOS 10.3.3. I've done every system update that I've been notified of.
JA: Have you installed any updates recently?
Customer: To the system, or to the apps I've got on the phone?
JA: What troubleshooting have you tried?
Customer: I've checked the battery health, done all the tips recommended to save battery life (shutting down background apps, using non-graphic heavy screen switches, etc.).
JA: Anything else you want the Mac Expert to know before I connect you?
Customer: Just that I admit to doing a decent amount of game playing, and I know that does drain the battery- but the rate has increased sharply recently.
Submitted: 1 month ago.
Category: Mac
Expert:  Russell H. replied 1 month ago.

Hi, thank you for contacting My name is***** will do my best to provide the right answer to your question.

That sounds as if either the battery were failing - oddly though, in an irregular way. Or more likely, as if its contacts were dirty or were not making good contact, were loose, etc.

Examine the metal contacts on the battery, and the corresponding contacts in the computer. Are any of them bent, or dirtied looking, corroded or rusted, etc.

Customer: replied 1 month ago.
From what I can see in the charging port no- but one metal bar on the charger itself is discolored, on both sides.
Expert:  Russell H. replied 1 month ago.

OK! That might very well affect things. Now, cleaning that contact is an obvious thing to try, but if the contact on the charger is delicate, it might simply break off. Trying buffing it gently with light-grit sandpaper might prevent breaking it but clean it enough for it work well, after blowing away all the grit once you have gotten it to where it looks shiny once more, and is neither broken away nor bent by this process. (Cloth cleaning might catch on it and bend or break it.)

Replacing the charger is another possibility. Let me know if you'd like references to possible sources of a replacement charger.