Monitor Charging New MacBook Pros - potential issues?

[inigo85]

Hello

I currently have a base MacBook Pro for personal use and in a month or so I'll also be receiving a 16 inch M1 Max for work.

I'm looking to purchase a monitor to use for both (a Dell U2720Q) that offers 90w of charge via USB-C.

I just wanted to pick people's brains on the forums as to whether charging via USB-C from the monitor would gradually harm the MacBook Pro batteries over time as opposed to using the MagSafe Charging?

For the base MacBook, 90W is more powerful that the standard 60w or so that came with the MagSafe charger...yet Apple also sell the 90w MagSafe charger as an upgrade, so I'm guessing there should be no issues there with the base (although I did read somewhere that fast charging a battery, which can be done on the more powerful chargers, can damage a battery over time...don't know how true that is...)

On the other side of the coin, will using a USB-C 90W charge from the monitor harm the 16 inch MacBook Pro's battery when it is running full pelt? I'm only wondering as the 16 inch comes with a mammoth 140W MagSafe charger. Is there any potential damage caused to the batteries by using 90w instead of the full 140w?

Many thanks for any help or advice in advance!

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[badsimian]

It will be fine. PD specs mean that negotiation goes on as to how much power a device needs and draws. It often isn't the full 60 or 90w anyway, those are maximum lilmits. Secondly Apple has a lot of battery wear mitigation technologies in play as well when you choose the Optimised battery charging option in System Preferences. I wouldn't worry about it. Worst thing that might happen is if your 16" runs at full whack and requires more than 90w...it might drain the battery on top of the power via USB-C.

 

[throAU]

I just wanted to pick people's brains on the forums as to whether charging via USB-C from the monitor would gradually harm the MacBook Pro batteries over time as opposed to using the MagSafe Charging?

It shouldn't do.

As an aside, I've been running my 14" almost entirely off one of my old MacBook Air chargers when at work because it simply doesn't need the power. I have the supplied 97 watt charger under my desk at home, but rarely need it. 30 watts is enough to charge it while doing light work at work.

The MacBook/device itself will control the charging, not the charger. I've regularly charged my iPhones, iPad Pro, AirPods, etc. via 30 watt MacBook Air chargers (i.e., 2-6 times the supplied charger size) with no ill effect.

Worst thing that might happen is if your 16" runs at full whack and requires more than 90w.

In my experience, pretty unlikely. I don't think the M1-Pro models ever draw much more than 60-65 watts even fully loaded from the testing I've seen. The 97-147 watt charger is, I think so you can charge it quickly whilst still running it hard. . Very different from previous Mac laptops which have always been supplied with totally inadequate chargers (my previous models have taken hours to charge and barely been able to charge and work hard at the same time at all).