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The smaller of Apple's MacBook Air laptops featuring dual microphones and 802.11ac Wi-Fi connectivity.

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MagSafe charging & LED inconsistent w/3rd party power supply

I received some MagSafe 1 connectors a while back that were cut off from defective power supplies. I happened to have a 15v/3A DC Toshiba power supply lying around, so I replaced the power supply's connector with an L-shaped magsafe 1 connector (good, beefy solder joints, lots of insulation between the wires, etc).

I've been using this power supply for for a couple months now strictly at home and I've noticed that it performs a bit erratically at times.

1.) The LED on the MagSafe 1 connector almost always remains on even when I unplug it from a MacBook Air and/or the MagSafe 2 adapter.

2.) Sometimes the status bar displays "not charging". If I unplug it a couple times from the MacBook or slowly connect the MagSafe 1 connector + adapter to the MacBook, it may begin to charge after about a 10-20 second delay during which the status bar displays the message "battery is not charging" and "power source: power adapter". On a few occasions I've unplugged the power supply from the wall for a couple minutes and then plugged it back in and the MacBook was often (not always) charging again.

3.) When I leave the MacBook on all day while plugged-in to this power supply, I'll sometimes come home to a 0% battery.

I briefly took a look at this article on how the MagSafe charging protocol works:

http://www.righto.com/2013/06/teardown-a...

But It didn't really discuss the power supply attached to the MagSafe connector. The Macbook clearly recognizes the MagSafe connector - I can read the serial number and other info in the system profile.

Does anyone know if there's a chip inside the MagSafe 2 adapter? Could the adapter have any implications here?

Is Apple doing some kind of proprietary magic inside their power supplies? Any help is greatly appreciated. Thanks for reading.

Here's a photo of the power supply I'm using:

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Yep, its Apple magic! ;-}

Sadly, there is some logic within the power adapter that interacts with the system via the middle connector. The connector it's self is not the issue it's the signal within the middle pin between the power adapter and the system thats is the issue here.

Basically, you'll need to get a real power adapter unit to run or charge your systems battery. Hopefully you didn't damage the logic inside your system with your home made power source.

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To clarify, I didn't make the power source, it's a commercially available power supply distributed by Toshiba. The middle pin isn't connected to the power supply, all that the power supply seems to give is +15v and ground. Why would it damage the logic board? Isn't the maximum input voltage of the MacBook Air 18v before the fuse blows?

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My point was its not an Apple Power adapter. Using a substitute which does not have the means to interact with the system puts your system at risk. There's more to just applying power with these Lithium Ion batteries.

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that is correct. Your Toshiba power supply only puts out 15V. No, the fuse will not blow over 18V. The fuse "blows" when the current carried exceeds the rated value for an excessive time. anyhow, that is not the issue here. Get a correct charger to at least properly troubleshoot your computer. You have a $1200 computer, so why not spend the $30 for a proper power supply.

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Because I want to know how it works.

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"My point was its not an Apple Power adapter. Using a substitute which does not have the means to interact with the system puts your system at risk. There's more to just applying power with these Lithium Ion batteries."

Oh, ok, so what else is involved in charging the lithium-ion cells in a MacBook air, apart from the charging circuitry inside the computer and the tiny circuit inside the magsafe connector?

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