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I've just bought and installed a replacement battery for my 15" late 2012 MBP (non retina).

The battery is not OEM but from iFixit as they are in my opinion the next best thing.

I was interested to see how the new battery fares, so I installed this battery monitor app to see how it was. See screenshot of report from battery app monitoring app below.

I'm currently charging on a 60W original Apple charger (as I understand it, the 85W is optimal, but not necessary).

Is it correct that the charging with value = 5.5w, shouldn't it be c. 60w?

I'm also getting very long estimated charge times, it first started at c. 5hrs, and was slowly charging. But now it seems to be slowing down at around 40% charge, and is saying time to fill the battery is c. 10hrs.

screenshot of report from battery monitoring app

  • How could it be 60W? You're using the MacBook, right? If 100% of your adapters capacity was used to charge the battery, the MacBook wouldn't be on. – Allan May 21 '18 at 21:25
  • @Allan its defiantly 60W (it says it on the side of the charger). To answer your other question i have no idea how it works exactly, but t is working. – sam May 21 '18 at 21:36
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    You misunderstood my first comment... It was a rhetorical question. If the adapter is 60W, how can your MB be consuming 60W to charge and operate at the same time. That would be greater than 60W. – Allan May 21 '18 at 21:43
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Is it correct that the charging with value = 5.5w, shouldn't it be c. 60w?

This is expected behavior.

The 60W rating on the power adapter is the maximum amount of power that the adapter will supply. Note that it's not the amount that will be "pushed," but the amount that can be drawn from it.

Slow Charging Speed

... for my 15" late 2012 MBP (non retina)...I'm currently charging on a 60W original Apple charger (as I understand it, the 85W is optimal, but not necessary).

This is an incorrect assumption on your part. The 2012 15" MacBook Pro requires the 85W charger - see Apple: Find the right power adapter and cable for your Mac notebook

This is why you're seeing the very long charging times - your MacBook Pro is "asking" for more than your adapter can deliver and since the adapter can't supply any more, it lowers the power to the battery charger in favor of the compute requirements.

Your MacBook has two operations going on: powering the system and charging the battery. In this scenario, priority is given to powering the system. If you were to shut it down, the priority would naturally go to charging the battery.

Seeing only 5 to 6W of power being allocated to a running computer is perfectly fine (for the 60W charger); the power is being divided to account for your current use. Use the correct charger and it will operate and charge correctly.

Further Reading

There's additional questions/answers on this very topic. Please see the following links for further reading:

TL;DR

You're using the wrong charger. Get the 85W charging adapter and your charge times will decrease to normal levels.

  • Thanks @Allan, ive just plugged my MBP in at work using a 85W mag safe charger and its saying its charging with 2.8w. The battery is 96% full and the time remaining for a full charge says 1hr 20mins. Does that seem right ? – sam May 22 '18 at 9:13
  • Sounds correct. Keep in mind, when you're "near full capacity" it slows down charging. Turn it off and time how quickly it goes to a full charge (green LED) – Allan May 22 '18 at 9:27
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This would be normal if your MBP is using lots of power itself. You can check this with Activity Monitor. Or a simple experiment: Turn brightness all the way down and see if you charge quicker. If the Mac is turned off, it should charge reasonably fast.

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