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From the pmset man page:

POWER SOURCE ARGUMENTS

-g with a 'batt' or 'ps' argument will show the state of all attached power sources.

[…] Certain Apple battery calibration tools may temporarily disable battery charging, even though your Apple portable is plugged into AC power.

Such tools will never surprise you with this behavior; you will know it's happening. This state will be reflected in an additional line of output to 'batt' or 'ps' readings, including the pid of the app inducing this behavior.

     'ChargeInhibit':    1432

So, does any piece of publicly available software exist to force the battery not to charge?

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I am a little bit curious here, why would someone want to do something like that? Batteries are meant to be charged and dis-charged to keep them healthy. Also, once the battery is fully charged will stop of course. –  bluewoodtree Apr 6 '13 at 3:15
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The SMC already prevents charging if starting with a 93% or higher battery level, but a Li-Ion battery is ideally stored at about 40%. I am one of those who hardly ever move their computer from the desk. –  Ryccardo Apr 7 '13 at 18:41
    
Okay, now I understand the point. However, you will be fine by just having the battery fully charged and discharge it to 20 % at least once per month. The benefit of storage at 40% is more important if you are planning to store your battery for a year or so without using it. –  bluewoodtree Apr 7 '13 at 22:16
    
And that damn SMC design always cause me to worry about the healthiness of my battery. LOL! –  Shane Hsu May 21 '13 at 9:54
    
Hi, I tried to find this out some years ago... but I was not able to find anything. My idea was to control the charging of my macs with the power generation of my windmill :-) –  otmezger Aug 18 '13 at 17:54

5 Answers 5

If you use a small piece of tape to block the middle (signal) pin on your MagSafe charger, your Mac will not charge because it can't identify the charger.

enter image description here

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If you remove the charger it also won't change. –  CousinCocaine Jun 4 at 18:50
    
Of course, but OP wanted to know how to disable charging "even though your Apple portable is plugged into AC power." –  Kevin Chen Jun 4 at 21:58
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I confirm, this works. I am able to stay at 40% charge forever while using AC power, which is exactly what OP wanted, albeit the solution is not software but hardware :) I have Magsafe 2 –  Sergei Jun 10 at 22:02
    
As the days go by, I can see the percentage slowly drop due to self-discharge. This is awesome solution for MacBooks used as servers, or MacBooks used as desktops. This answer deserves more upvotes! –  Sergei Jun 21 at 8:44
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I used this to make my MacBook work with an underpowered car inverter so it would draw less power and it worked great. Thanks! –  Justin Cherniak Jul 11 at 23:21

Not an Apple-approved answer, but to solve your root cause (to train battery regularly when your MBP is always at your desk), consider surge protectors with scheduled on/off (example, about $40 in Russia). You can program it to turn off in the beginning of night, and to turn on about 4am so that battery is charged back by the time you show up at your desk. To save charge cycles, I believe it should be performed not daily--but maybe once or twice a week.

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how many rubles is that :) great and effective answer +10 –  Buscar웃 Apr 14 at 23:52
    
@Buscar웃 Thanks :-) –  yurkennis Apr 15 at 9:14
    
A simple timer ($5,-) would do the same, right? –  CousinCocaine May 30 at 7:54
    
@cousincocaine Much more manual work, isn't it? –  yurkennis May 30 at 14:16
    
No, is digital, not much work. –  CousinCocaine Jun 4 at 18:51

I don't believe there is any way to disable charging while plugged in (if you have a non-removable battery, as recent models do).

Apple used to make an Airline MagSafe Adapter (which didn't charge computers, so as to avoid tripping the airplane outlet's circuit breaker (or whatever the cause) that resulted in no power being provided at all), but it was discontinued years ago.

Your computer will automatically stop charging once it reaches a high enough charge. You can't "disable charging" except by already having a charged battery.

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No it is not possible to discontinue charging while it is plugged in. This is a default function that enables as soon as you plug your portable charger in power source, and if any software does that, then it is surely going to harm you device as well as battery even more. So it is better to keep it that way.

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When I opened the cord (between the transformer and the magsafe connector) for the charger on my macbook pro, there were only 2 wires. Therefore its seems likely that the tiny middle pin on the magsafe connector does not do anything electrical !

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