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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?

Jawa
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Ryccardo
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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 06 '13 at 03:15
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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 07 '13 at 18:41
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    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 07 '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 09:54
  • 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
  • I need this because my solar panels can't both charge AND run my computer at the some time (either is fine) – diachedelic Aug 07 '16 at 04:28
  • It is so unfortunate that we don't have an answer to this in software. It would really be helpful to extend battery life. I'm also surprised Apple does not provide this out of the box. – davidpfahler Sep 18 '16 at 16:00
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    You might want to look into tools like AlDente (comes with a GUI), or bclm (CLI).

    Those are softwares that write to the BCLM (battery charge level max) of SMC, so you can set a upper limit to which your Mac will charge its battery.

     – toaruScar Sep 03 '20 at 03:46

6 Answers6

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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

Kevin Chen
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    If you remove the charger it also won't change. – CousinCocaine Jun 04 '14 at 18:50
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    Of course, but OP wanted to know how to disable charging "even though your Apple portable is plugged into AC power." – Kevin Chen Jun 04 '14 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 '14 at 22:02
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    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 '14 at 08:44
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    Yep! On laptops whose CPUs have higher TDPs, you might notice that the battery level also drops when you make the computer work hard and the charger can't provide all the power needed. – Kevin Chen Jun 22 '14 at 13:55
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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 '14 at 23:21
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    So it does not charge the battery, but it does use the power for normal consumption. Nice solution! – CousinCocaine Sep 30 '14 at 12:35
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    This is gold. I wish I knew this right after I started using my laptop. Many thanks for the tip! – WhatHiFi Jul 05 '17 at 18:20
  • Careful with this. Worked for months, then it smoked a charged almost damaged my mac and started a fire. Charger tip melted and burnt the charging port where the MagSafe connects. I used transparent tape like the photo. Maybe I should have used electrical tape. But, I think a timer like yurkennis suggest is safer. – Skurfur Apr 12 '21 at 12:04
  • can anyone test this with the new magsafe 3? – anonymousaga Feb 05 '22 at 21:16
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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.

yurkennis
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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.

Alex Todd
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My Magsafe currently has one of the outer pins stuck in, I cant seem to get it to come out, Ive ordered a new chord, but the interesting thing is that its not charging the battery. It is powering the Macbook pro, but my battery percentage is not going up. maybe try sticking some PVC tape over one of the outer contacts if you don't want the battery to charge?

jclights
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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.

V2Blast
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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 !

investigating charger and batt
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