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Comment by irrational | Hacker News Reader

I do. I rarely need to take it anywhere.

This destroys battery. You do need to charge and discharge the battery frequently.

Got any credible sources that back that up?

My 2015 13" MBP has been charged 221 times in 4.75 years. It has been plugged in for the vast majority of the time, yet still shows 88% total capacity and will still last 8+ hours doing standard web dev stuff.

My iPhone gets discharged every day, but its capacity is down to 78% after just 2.5 years.

Do you discharge your iPhone all the way to 0%? The bottom 20% are also not so great for battery wear.

Ideally you would stay between 20-80% (only charging to 100% and discharging to 0% when you really need it)

I try not to but it has been below 10% many times (and occasionally so empty it turns off).

Now WFH, so it has been plugged most of the time since late March and I'm really just nursing it through until the newer phones are released so I can decided whether to get the updated SE or the newer model.

What’s to say your iPhone isn’t holding 20% in reserve cutting off the phone early so the battery doesn’t get into that 0-20 bad zone.

I think this is false. Lithium-Ion batteries (in contrast to e.g. NiMH) do not have the memory effect [1]. It's actually charge/discharge cycles that reduce battery life for such batteries [2]. Older MacBooks were only rated for 300 charge cycles, nowadays up to 1000.

This also reflects my experience. In recent years, my MacBooks with the highest remaining capacity have been those that I had pretty much always connected to a charger, only using it on battery during meetings.

[1] https://en.wikipedia.org/wiki/Lithium-ion_battery [2] https://support.apple.com/en-us/HT201585

Do note, however, that keeping the battery _in_ while the device plugged in usually results in the battery kept "floating"; which results in many short charging cycles (i.e. discharge to 99%, then top to 100%, rinse and repeatt). This is what this type of "battery management" updates are designed to avoid, and many manufacturers allow configuring these cycles in ways that are much softer on the battery (e.g. avoid 100%).

How frequently? Could you please point us to some source?

I also keep my MBP plugged in almost all the time. Long ago I had a MacBook Air and I absolutely wrecked its battery pretty quickly by doing a full cycle every day.

Seems strange that they don't put code in to repeatedly drain the battery to 90% and then charge it again when plugged in, if that were the case.

What they should do is to allow user to switch between standard (works like now) mode and battery-conservation mode, where user does not care about battery and system does its best to preserve battery health. I'm using my laptop on charger 99% of time and when I need to transport it, I could switch that mode few hours in advance.

The happy range for a modern battery is 20-80%.

The bottom and top 20% are what's causing the wear, so merely staying between 90% and 100% won't do you any good.

Source? If you are letting charge drop in that range and charge again, you are creating charging cycles. Charge cycles reduce the capacity of Li-Ion batteries.

https://support.apple.com/en-us/HT201585

This is an extremely bad UI for battery management logic. If that is the case, a computer that is always plugged should discharge and re-charge the individual battery cells one by one to enlarge their lifespan.

IIRC you should strive to never reach the extremes; i.e. keep in the 20–80% range in order to maximize its lifespan.

Another tip was to avoid rapid energy consumption (such as from intensive use of CPU or discrete GPU usage) while on battery.

My main issue is that whenever you plug an external monitor, this automatically trigger the discrete GPU, and I'm using an external monitor for working from home (due to the cervical), so I'm mostly using the charger.

That's the opposite of accurate. Battery life is measured almost exclusively in charge/discharge cycles. More cycles == more reduced battery life.

Not true. a battery left 4.2v at over 100F will degrade very fast.

Degradation happens most severely if at high voltage and high temperature.

Without high temperature it is completely fine to leave a battery at high voltage.

In some cases, high cpu/gpu utilization will drain the battery when plugged in.

Is this 2010 advice or 2020?

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