Mojave Battery Charging Controls?

Question

Mojave Battery Charging Controls?

If laptop battery life can be maximized by keeping battery charge in the range of 50% to 90%, or even if my percentages are not quite right, why can't Apple write battery management controls into Mojave that turn off the charge current below 50% charge and above 90% charge?

Without built-in controls, I have to keep an eye on my charge level and unplug my charge cable below 50% and above 90%. Is there a reason why this type of control cannot be written into the MacOS?

MacBook Pro 13", macOS 10.14

Posted on Jun 21, 2019 5:17 AM

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Answer 1

John Galt

Level 10

141,332 points

Jun 21, 2019 1:04 PM in response to fourwheelcycle

fourwheelcycle wrote:

... Maybe an Apple rep will jump into this thread and tell us.

They don't do that.

Portable Mac power management systems (both hardware and software) are considered highly valuable intellectual property. Apple's Mac division absolutely, positively does not discuss those details with anyone else.

The point is that you will hear all sorts of weird allegations posted to this site, and it's presumptuous to assume a MacBook's power management isn't already highly refined. Apple has more experience extracting maximum performance from portable devices than any company on Earth. The overwhelming majority of MacBook users never need to replace its battery over the entire Mac's useful life.

Luis Sequeira1 already posted the starting point for all that is known to the rest of us. Here's some more: Batteries - Maximizing Performance - Apple. Follow them and your MBP's battery will last a long time. If you want to learn more than that, the best I can suggest is to participate in the Developer Forums. Every once in a while a macOS engineer has been known to inadvertently divulge something else (I'm only being partially facetious).

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Answer 2

Lexiepex

Level 6

14,102 points

Jun 21, 2019 6:06 AM in response to fourwheelcycle

"I have to keep an eye on my charge level and unplug my charge cable below 50% and above 90%".

that is exactly what you don't have to do.

let the charger cable connected. Once in thre weeks unplug and work until the charge level is 30-50% lower than full, then

plug in again for the next three weeks.

Your battery is designed for a number of (charge) cycles, for example 1000 cycles. A full charge cycle is when the number of partial charges combined is a full charge cycle (from empty to full). The way you treat the battery is giving it charge cycles continuously.

To see the number of charge cycles: open SystemInformation (in Utilities)->select "power" on the left side->on the right side you see the battery information.

Never let the battery going down to fully empty, that is bad for the battery.

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Answer 3

Jun 21, 2019 6:07 AM in response to fourwheelcycle

There is no need to hold yourself hostage to this. Your mac will work fine. Don't fret about it.

Batteries last for over 1000 charge cycles. I work on my laptop for hours every day, on a desk, so I keep it connected to power. This works better than continuously discharging, then connecting, recharging, then disconnecting. Doing that would actually reduce the life of your battery, as you'd be using up many more charging cycles.

I replaced my battery after about five years, and some 1200 cycles. The second battery will probably outlast my now oldish mac.

Had I recharged twice a day, I'd have to have replaced it years ago.

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Answer 4

Jun 21, 2019 6:43 AM in response to Lexiepex

I am certainly not an expert on batteries, but from web browsing I understand battery life is affected by the number of charge cycles and the number of times a battery is deep discharged (below 50%?) and/or fully charged (above 90%?).

Maybe my understanding is wrong. Do you have a reference that says battery life is only affected by charge cycles and discharges to empty?

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Answer 5

Jun 21, 2019 6:51 AM in response to Luis Sequeira1

Apple's support page on battery management says one battery cycle is measured as using 100% of the battery's capacity, which can happen over several cycles of use and recharging. I don't think plugging in the charge cable at 50% and unplugging it at 90% is measured as one charge cycle.

I do agree, it is probably not even necessary to fret about battery charging. In fact, I have never had to replace an Apple laptop battery. However, I do wonder whether it might be possible to program charging current switching controls into the MacOS.

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Answer 6

Jun 21, 2019 7:15 AM in response to Luis Sequeira1

Thanks for that Apple page reference, I had not seen it. As it turns out, I am a long time remote control car user and I am very experienced in recharging batteries. The page you referenced notes that allowing a battery's temperature to rise to a high level as it approaches full charge at high amperage levels (relative to the battery's amp hour capacity) will shorten the battery's life. The way to avoid this risk is to charge at low amperage levels (relative to a battery's amp hour capacity) or switch to a very low (trickle charge) amperage level as the battery approaches full charge.

Apple says it switches to a trickle charge level above 80% charge, and I am sure this does extend battery life. However, the Apple page does not comment about possible impacts on battery life related to discharges below a certain level or full charges to 100%. I do wonder whether discharges below 50% and charges above 90% may also have some impact on battery life, and whether Apple could include management controls to switch the charge current completely off above and below some percent of charge limits.

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