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I'm running Sierra 10.12.6 on a 2015 MacBook Pro and I was wondering if anyone knew a way to trick the OS into thinking the battery is connected when it's actually unplugged.

I'm sure you guys will want to know why in the first place...I keep my mac plugged for long periods of time and it's messed up my battery capacity ( down to 70% in just 300+ cycles).

mac_33
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Your question assumes that something is wrong on the basis of your battery health only being at 70%. It's not clear how you're getting this figure, but a battery health of 70% after 300 cycles sounds perfectly reasonable to me if what you're measuring is the number of cycles remaining. Otherwise Battery Health is not usually represented by a percentage value, but in terms of Normal, Replace Soon, Replace Now, and Service Battery.

While it used to be in years gone by that Apple recommended allowing your battery to drain somewhat on a regular basis, this is no longer the case. In other words, keeping your MacBook Pro plugged into an AC power source for prolonged periods will not mess up your battery.

You may want to refer to what Apple has to say about their batteries for more information.

In summary:

  • Apple lithium-ion batteries use fast charging to reach 80% of their capacity and then switch to slower trickle charging to complete the charge.
  • Charge your MacBook Pro whenever you want. Many people believe you need to let them discharge 100% before recharging. This is not true.
  • Ambient temperature is one of the biggest factors in battery health/life. MacBooks are designed to work at their best when ambient temperatures are between 16° to 22° C (62° to 72° F).
  • It’s important to avoid exposing your MacBook to ambient temperatures higher than 35° C (95° F)
  • If you're ever going to store your MacBook for long-term without usage, it is best to store it totally powered down and at only about half charge.

Also, some of the latest research suggests that one of the most important determinants of what ruins a battery is time, and that's not something you can do anything about.

Finally, there is no way of safely tricking your Mac into thinking that your battery is connected when it's not. It will cause other issues for your MacBook and, in the event of a power failure, you have no built in uninterruptible power supply.

Monomeeth
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  • I'm not sure how to address this, but maybe you should drink a beer and chill before you answer questions (just a thought). Irregardless, I'm fairly sure the how is pretty irrelevant (it's not like I measured and did the math myself), and I don't know how you can assume it's perfectly reasonable when apple says the following: "MacBook Owners, Your battery is designed to retain up to 80% of its original capacity at 1000 complete charge cycles." ([https://www.apple.com/batteries/service-and-recycling/]). Nevertheless, I appreciate the input...I suppose. – mac_33 Nov 16 '17 at 03:59
  • Posting a comment is fine. :) Yes, a MacBook battery is designed to retain up to 80% of its original capacity. But that is different to 'battery health' which is usually measured in terms of Normal, Replace Soon, Replace Now, and Service Battery. It's not measured in terms of a percentage, although percentages are used to indicate a battery's Full Charge Capacity, Design Capacity, and its current state of charge. I guess you could say that your battery has 70% of its cycle life left in it, but that's not an indicator of health. – Monomeeth Nov 16 '17 at 04:22
  • To check your battery's health: Hold the – Monomeeth Nov 16 '17 at 04:22
  • Oh ok, that clears up what you meant by how. I wrongly assumed that health would refer to current mAh capacity not just a description. By 70%, I literally mean 70% of the original mAh capacity. – mac_33 Nov 16 '17 at 04:38
  • You may find coconutBattery useful (if you haven't already come across it). You can try it for free and it gives you some accurate info re your mAh capacities, as well as other useful data. – Monomeeth Nov 16 '17 at 05:37
  • That's where I'm getting the mAh capacity I'm quoting, that and two other apps to account for error. – mac_33 Nov 16 '17 at 05:39
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I keep my Mac plugged for long periods of time and it's messed up my battery capacity ( down to 70% in just 300+ cycles)

It doesn't work this way anymore. In this answer, I describe the two factors of what contributes to battery life: time and cycles.

It is entirely possible to get a battery with diminished capacity with relatively few cycles on it - it's older than your machine. You are proceeding under the assumption that the battery wasn't older, unused stock and/or the battery itself wasn't defective from beginning. The bottom line is...it happens - you get faulty components.

Leaving your Mac plugged in won't affect your battery because a cycle is one full discharge and recharge. So, if it only discharges 5 percent then recharges, it will have to do this 20 times to count as a cycle.

I was wondering if anyone knew a way to trick the OS into thinking the battery is connected when it's actually unplugged

Could you? Sure, but you have several power rails you will need to supply voltage to in order to trick the SMC and charging circuits into believing a battery's connected. This happens at the hardware layer long before firmware and especially the OS comes into play, so the hack will involve a fair bit of electronic engineering know-how.

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It's by far cheaper, safer and more productive to get the battery changed out and be done with it.

Allan
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  • I suppose I did assume the battery was fine to begin with, but the fact is that this is my third MacBook and the same thing has happened to all my batteries. The other two, I changed the batteries but I don't want to have to do that again. The simplest constant I can think of, is my charging habits and the fact that deterioration was usually mediated when I regularly used cycled charges. However, it's safe to say I hate batteries sometimes. As for the SMC, that really clears up my options thanks. I guess I need to re-phrase my question... – mac_33 Nov 16 '17 at 16:30
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    The real issue is that the CPU is throttled whenever the battery is disconnected. So I guess my real question is how to get around the CPU being throttled. – mac_33 Nov 16 '17 at 16:32