This is a simpler version of https://manifold.markets/dreev/will-my-battery-redqueening-strateg
I have a 16-inch Macbook Pro made in 2021. It has a Magsafe charger that charges extremely fast. You can also charge it with a phone charger with one of the USB-C ports, which takes forever. Is one or the other generally better for battery health?
(I'm actually biased towards the phone charger because (a) that way I can leave the Magsafe charger in my bag for when I travel and (b) the phone charger is so slow that it's easier to keep the battery mostly in the recommended 40-80% charge range. But this may be misguided!)
This resolves to YES if Apple has official guidance recommending using the Magsafe charger or someone who knows what they're talking about has an opinion.
PS: Turns out I really never need the Magsafe charger, even when traveling. I just charge it overnight with a phone charger, or use a phone charger while working and it keeps up well enough.
1,000I'd be surprised if there's any difference. Newer ones are supposed to have software managing the battery for you, such that they'll rate-limit the charging or stop charging at 80% if usage patterns indicate that will extend the battery life.
So regardless of the charging source, it shouldn't matter.
I'm not going to bother researching battery chemistry to get authoritative proof for 800 mana though...
@Sjlver Do you know how you'd resolve it? I'm happy to add a bunch of liquidity or a bounty to incentivize more research till we're confident of the answer.
A bit more research brought up this explanation:
https://www.dell.com/community/XPS/Will-charging-at-lower-wattage-increase-battery-lifespan/td-p/7579834
Conclusions are similar to before: while lower wattage is in principle good, the charging controller in the laptop will automatically adjust the wattage it gets from a powerful charger, so in practice powerful chargers do not pose a risk.
Other settings apparently have a larger effect on battery life. For example, you could limit the maximum charge to 80% to avoid the stressful high-voltage charge phase from 80 to 100%. For a MacBook, you can find this under System Settings > Battery > Optimize battery charging.
USB-C chargers can be anywhere from 15W to 100+W, and it's the wattage, not the connector, that matters.
A 15W phone charger supplies less than the peak power draw of a Mackbook Pro, which means that if you're using it while plugged in to a phone charger, it will alternate between charging and discharging based on processor activity. Whereas if you use it while plugged into a fast charger, it will fill the battery then leave it alone. (If you mostly use it in a fixed spot always plugged in, it will by default instead charge it to 80% and leave it there, to extend battery life. See the "Optimized battery charging" config setting in system preferences.)
@JamesBabcock This sounds helpful! But is switching between charging and discharging harmful? I hear about minimizing charge cycles but that doesn't seem to literally mean number of times it flips between charging/discharging but rather total amount of energy fed to the battery.
@dreev I'm not a battery chemist, but I think it's the amount recharged that causes wear, not the transition, so discharging 1% then recharging 1% would be 0.01 cycles. (The main caveat being that wear is worse at higher temperature, and a 0-to-100 charge produces a lot more heat than a 50-to-51 charge).