Unibody MacBook Pro models with 13" displays produced from 2009-2012.

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Battery not detected and auto turn on

Good morning,

I was trying to get a working MacBook Pro from two different, not working entirely. I will try to explain everything as better as I can.

One of the two did work perfectly, the problems where a completely broken screen, broken trackpad and very ruined casing.

The other one was my original one, which had a long series of problem. Everything started with a hard-disk problem, apparently according to the mac partition it wasn't working anymore. So, since with the Windows partition everything was working fine, I resetted everything and reinstalled Mac OS. After that things seems to go well, but at some point the Wi-Fi stopped working suddenly. So I bought a new wi-fi card from ebay, installed it, and started using the mac again. Now the wifi was going perfectly, but a new problem arised. The battery was not detected anymore. I then brought my mac to the apple store to check for the problem and they told me after some struggling that probably the mainboard had to be replaced for some unknown reason.

I then tried to fuse those two macs into one, by changing my motherboard. And then the same problem as before arose also with this new one. Battery was not detected and now also wifi was not working.

In detail I have the following problems:

-> The battery is not detected, it's like no battery is connected to the mainboard. MagSafe adapter show always green light and without it, it doesn't turn on.

-> As I connect the MagSafe to the turned off mac it automatically turns on!

-> Wifi is completely not working, as if I have nothing connected to the mainboard.

What I already tried:

-> SMC and PRAM reset. (SMC probably can't be completed in the right way, because of the auto-turning)

-> Tried another battery.

-> Tried another MagSafe. (Now I'm using one of a 15'' MacBook Pro)

-> Starting with the completely connected Motherboard I started to detach every device from it, until I got to having only Fan connected, to see if some device was causing the auto turn on.

Anyone have any suggestion of what is happening to my motherboards? (I forgot to mention that both behave the same way, auto-turn on without any device connected)

Thank you very much!!

Answered! View the answer I have this problem too

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Auto turn on is normal behaviour for Intel i5/i7, if the charger is plugged in and the battery has just been reconnected or is not detected.

With the battery issue, you likely shorted the pins above where the battery plugs in and sent the battery 12V to the SMC data line, which detects and communicates with the battery. This would have damaged this part of the SMC, which is responsible for recognising the battery.

One way to check the above, is to unplug the charger whilst it is on the Apple logo, with a battery plugged in (which has some charge). The MacBook will stay switched on until it gets into the OS, at which point it will shut down, since it thinks the battery is not plugged in.

The only way to resolve the above is to either replace the board, or remove and reball an SMC from a board of the same year, and solder it onto your one (which isn't recommended for beginners).

For the same two issues to occur on both boards, I imagine there must be an intermittent fault with the wifi cable and you sent 12V to the SMC when disconnecting the battery on the second one. I doubt both boards will have the wifi issue related to the board, but it is highly likely you damaged the 2nd one the same way as the 1st

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I tried this thing with disconnecting the logo on my old board, and it is going exactly as you told unfortunately for me. I will try with the board that was previously working and see if I notice the same problem... hopefully not but I assume yes ahahah


I have the same issue, but when I tried disconnecting with the logo on, the mac booted up and didn't go off and still shows cross icon on the battery.

Also my mag safe is having light green light instead of bright green and I am not able to see the battery charge indicator either. The mac fan speed is running at full and is showing N/A / 0 RPM on TG PRO app. Please help. It was working perfectly until suddenly I reseted the SMC and PRAM for some reason and it went buggy and now the mac auto boots when plugging the mag safe and power button is unresponsive.


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I believe auto turn on is normal behavior for if the power was cut out, or the battery dead. There is a chance that both boards are bad, it's almost what that sounds like. Have you tried running Apple Hardware Test yet? That can help tell you what's wrong. You should be able to run it by holding the D key when turning it on.

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I didn't know about that test, I will try it and check. Thank you!!

I think that one of the two battery should not be completely dead... I should check voltage on them...


I runned it and it detected no problems. You where right with your guess that the auto start is due to the missing battery, as soon as I attached it, even though it is not detected, the auto start disappeared.


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