I have considered such a setup because I’d love to be able to go mobile easily. However what do you do about battery life? With Macs of the past 10-15 years, one can’t pull the battery out when desk bound. And to “go on battery” periodically as that Juice app would recommend would require losing attached storage and the monitors! How do you handle the dilemma of failure to exercise the battery vs having a battery-operated computer at the core of your home setup?
Frankly, nothing. I wasn’t aware batteries needed to be “exercised.” Perhaps that was true before the more sophisticated battery management capabilities of later versions of macOS? FWIW, the battery in my MBP M1 Pro, which I purchased three years and a few days ago, shows Battery Condition of “normal,” and a Maximum Capacity of 91%. The Battery Level histogram shows the charge being held steady at 80%, with a roughly daily ramp up to 100%. Presumably, that’s all managed by macOS.
Yup. Not an issue any more. I hardly ever use my 2021 16" MBP on battery and it shows normal and 100% capacity. (I have a 13" MacBook Air I use when I travel.)
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Not really a problem anymore. These days there’s options for “Optimized Battery Charging”. You let macOS discover your usage patterns and then charge accordingly. Just sit back and let the OS do the work for you. It will adjust charging patterns to ensure you don’t suffer premature battery aging, especially in setups where you’re plugged in a lot (or even almost always).
I’ll also add this data point. My main Mac is a 14" M1P MBP. It’s now been in heavy use for 3 years. I actually didn’t opt for any smart/optimized charging so it always gets juiced up to the max whenever it sees power. It’s plugged in a lot (over night or at the office), but I also move around various labs with it all day or spend time giving lectures with it not even plugged in. It’s a mix, but it’s seen really heavy use and no special care from my side. After 3 years the original battery is still at 88% health (385 cycles) and everything still works like a charm. Battery life is still awesome (a whole day of work without needing a charger) — as long as I don’t use Zoom that is. 
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That’s interesting. We both got the exact same computer at almost the exact same time. My battery is at 91%, but only has 183 cycles on it. I’ve had optimized charging on since the beginning. Clearly we have different usage patterns, and you’ve exercised your battery more, which likely accounts for the slightly lower max cap percentage.
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Thank you very much for the good news.
My 2015 MacBook battery doesn’t last long (1.5-2 hrs I think), but that’s partially because after its first year, I hardly used it, so it was often dead when I pulled it out and tried to boot it. That’s just no good for a battery, and that’s my fault.
But I’m really glad to hear that Apple has implemented their Optimized Charging for laptops, not just iPhones.
I was really hoping for the 80%-90%-100% slider on iPadOS 18, and I’m so frustrated they kept that off. They don’t even let us have the older “optimized charging,” which I can understand fits a phone better than an iPad. The ability to control the top charging level would have been a real blessing. I was hoping to take it easier on my 2020 iPad Pro. It charges so quickly when plugged into my Mac that it’s hard to catch it before it hits 100%. And because I’m so careful to avoid overcharging it, I often accidentally let it get down in the 20s or 30s. The iPhone works so much nicer because I can charge it whenever I want, knowing it will stop at 80%.
Adam will probably create a new topic from this…
It should be possible to create a Shortcut that gets the iPad current charge and switches a Homekit power outlet off if it exceeds 80%. Search for “Battery” in the Shortcuts app for ideas on how to do this.
Cumbersome but an interesting exercise in using Apple products.
Update: I have created a new topic about iPad charging:
My brother-in-law just bought a 14" M4 MacBook Pro Max computer and was told by two Apple employees to let his new computer run all the way down to zero to let the computer know the battery’s range – I believe that was the term. Personally, I have never heard that advice before. Does it ring a bell for anyone else?
It shouldn’t be necessary on a new computer. The Mac knows the battery’s capacity, and brand new, the battery would be at 100% life, so at that capacity or higher.
That used to be a thing way back in Intel Core Duo MBP times. You’d run the battery down and then charge it fully so that macOS could, based on that data, give you a reliable estimate for how much battery capacity you had and how much remaining runtime you’d have for a given percentage of battery use. Such calibration hasn’t been necessary in ages. Outdated advice.
Yes - that probably applied to NiCad batteries. it is not good for Lithium Ion batteries to drain completely.
What Simon and Michael said.
As others have commented, your MacBook will be just fine. I have used only Mac laptops since 1997 and all of them spent 90% of their lives plugged in on my desk and none had any battery problems. I still have a few of them (Wallstreet, PowerBook, MacBooks) and they are all still OK.
“Calibrating” batteries in that way used to be very common advice, especially for user replaceable Intel MacBook batteries.
It was intended to be done when replacing batteries or if you noticed performance that didn’t match expectations, e.g., suddenly going from 30% charge to 0% charge. For example, here are the instructions for NewerTech replacement batteries:
I can’t say that I’ve seen that advice for Apple Silicon machines. I suspect that the Apple Silicon Macs have much more sophisticated battery monitoring circuitry.
It’s known as battery recalibration.
All rechargeable lithium-ion battery packs sold to consumers have a controller chip that (among other things) monitors the battery’s life and reports back things like the current charge and capacity. (It is also responsible for blocking overcharging and for preventing attempts to charge completely dead battery).
For simple batteries, measuring the level is pretty straightforward. You measure the voltage and match it against a curve to get an estimated remaining life for some current draw. For instance, here’s the curve for a Duracell Coppertop AA battery. Although specs vary between brand and model, the curves are pretty consistent for all batteries that share the same chemistry (e.g. carbon, alkaline, NiCD and NiMH).
But it doesn’t work that well for lithium batteries. For example, a Duracell CR123A battery. Note the chart on page 3. The voltage level barely changes until the battery is about to die, followed by a sudden drop-off. So simple voltage-vs-curve approaches are not useful - they tend to report almost-full until the battery suddenly dies.
So for the battery packs you find in your computers and phones, the controller chip must use a different approach, and it must be calibrated for each battery in order to give an accurate reading. The usual method for calibrating this chip is:
- Charge the battery until it is full (and maybe a bit longer)
- Run your device until the battery dies (when the system software forces a shutdown)
- Charge the battery, without interruption, until it is full again.
This way the chip can see the voltage levels at every stage, from empty to full, and it can calibrate its output.
Some recommend that you do this periodically (maybe monthly) to keep the battery calibrated. Here’s an iFixit article about this:
But is it strictly necessary? If you typically run your device on battery and occasionally let it run down to shutdown, just make a point to let it fully recharge when you connect the charger and you’re good to go.
If you typically don’t do this (e.g. a laptop that is always connected to battery), then you might want to do this every few months. Or just ignore it, and be aware that the battery levels you see reported may not be accurate.
One word of warning - if you do this, don’t forget about it. I ruined a PC laptop’s battery this way. I started the procedure, but forgot about it while it was discharging. It ran the battery down to shutdown, but I didn’t come back to it for several days. The self-drain (from the computer being powered off with an empty battery) pushed its levels so low that it could no longer charge at all.
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That’s a different issue.
NiCd and NiMh batteries develop a “memory effect”. If you don’t periodically drain and recharge them, they lose their ability to hold a charge.
Lithium batteries don’t suffer from this, and if they are allowed to drain all the way to zero, they can’t be recharged at all. Which is why battery controller chips will disconnect them when the level gets close to zero, to ensure that they can be charged again.
But the controller chip needs to periodically be recalibrated in order to accurately report the current power levels. This recalibration usually takes the form of charging to 100%, draining until the controller cuts it off, then recharging to 100%. You don’t need to do this all the time, but it’s probably a good idea to do it on occasion.
To avoid unnecessary panic, that last point is worth emphasizing.
If a Mac is reporting that its battery has drained to 0%, that is not the same as “the battery is ruined, and it can never be recharged.” It’s similar to how a vehicle’s fuel gauge may say the gas tank is empty, but there actually is a little bit of cushion. If the battery actually gets to the “can’t be recharged” state, it will appear with an “X” through it in the menu bar.
It generally is not a problem for a healthy battery to go to 0% on a running computer with the computer in sleep/hibernating mode for a day or so, but as David reports, leaving it longer definitely can damage the battery permanently.
If a MacBook is going to be left unplugged for days or more, Apple recommends the device be powered down completely with the battery approximately half charged.
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I have some interesting information to add to this. Since March or April 2024, I’ve had my iPhone 15 on the 80% charging limitation, which makes me feel better about leaving it on a charger without having to check that it may have hit full. (I really wish I could do the same on my iPad Pro, which is 4 years old and losing battery capacity.)
What I wanted to add to the discussion is that from time to time, my iPhone does charge up to 100%, so this could be Apple re-calibrating the battery controller. It happens perhaps every 4 weeks; don’t hold me to that, as time flies.
I’ve had good luck using Chargie to manage charging my older iOS devices:
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It is. This is normal. If you go into settings / battery / charging where you set the charge limit, there is a link above the setting that says “learn more” : About Charge Limit and Optimized Battery Charging on iPhone - Apple Support
If you have Charge Limit set to less than 100 percent, your iPhone will occasionally charge to 100 percent to maintain accurate battery state-of-charge estimates.
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