Macbook Air won't charge, randomly works, can't figure it out

Macbook Air 11" (Mid 2013). My girlfriends MBA has had a weird charging problem. We can never tell if it's going to charge or not. Attach the Magsafe and it charges, disconnect, and then no charge for hours, days, we just never know. For the last week, when we connect the adapter it doesn't work. Then last night when we went to the Apple store and it was charging fine, and the Genius' couldn't really help. The only advice they gave was that it might be dusty, so they dusted the port.

The problem has been on and off. She has 3 different adapters, bought from Apple, but that doesn't seem to be the problem, they all work when the MBA is accepting a charge. We had the charging port replaced by an authorized dealer, and seemed to work fine, until a week later.

I've troubleshooted everything I can think of (resets, playing with finicky cords, adapters, or power outlets, etc) and have tried everything I could, scouring the web, but I can't seem to pinpoint the problem. We thought maybe it was the temperature of the MBA or the power adapter, but it's showed the same results hot or cold. There are several articles on the web about this, and seems to work for a lot of people.

One unique thing that I've noticed is that, when we attach the magsafe, we won't see a light, but if we open the screen (or turn on the computer, if it has a charge) then the light shows up on the charger. This has worked a couple times, but a few times it hasn't. Not a solid pattern, but might shed some light on what's wrong.

I consider myself pretty good at troubleshooting, but this has got me perplexed. Any suggestions would be great. Thanks guys.

Newtons Apple said:

I would take it back to the Apple tore and demonstrate the light problem on the MagSafe connector. It should be green or amber at all times when connected to the laptop.

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That's the problem, the few times we've went to get it looked it, it starts working at the store. It will be unable to charge for days, then take it into the Apple store, and the light shows up and starts charging. This has happened 3 times.

We were only able to reproduce the problem when visiting an authorized repair shop, when we were stressed for time. They ended up replacing the charging port, but the problem still persists.

julianps said:

The obvious thoughts are the quality of the power supply in your house/flat, whether all the MagSafe/MagSafe 2 pins are in good condition, the MagSafe port connectors as well. Beyond that there are two more thoughts; what sort of condition is that battery in (use coconutbattery) and is the BIOS capacitor still working?

On Intel's 'boards they long did away with BIOS batteries preferring small capacitors and I've read people working out these were at fault for their woes. Basically run the machine on battery till it's flat then leave it a day (or more). turn off all WiFi access and restart. If, on restart, it can't work out date and time that apparently suggests the capacitor's shot and you'll need a new motherboard, or a soldering guru to replace the 10p capacitor with one from Maplin's.

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Hmm Thanks for the information. I don't think it's the power outlets in your apartment because she uses it in her office also, same results. Same with the power adapters, cause she has 3 different ones. Also the Magsafe port was replaced, with same results.

I'll check into the battery part. Thanks for the info.