Is it okay to plug in multiple devices to a plugged-in MacBook pro (2021) all at once? Will this put extra strain on the battery or will it just draw directly from the power cord and not affect the battery itself? Essentially, can you use your mac as a charging station (while plugged in) without harming or depleting the long-term health of the battery?
MacBook Pro 13″, macOS 10.15
It depends on what you have connected. However, there really is no danger of overloading. The main issue would be if the demand is so high that the power supply can't supply enough and it taps into the battery for some power. I'm guessing your hope is that the battery is more or less unused. Using it doesn't "hurt" it any more than using the Mac normally on battery power, but any battery use inherently will result in degradation. That's just what happens with any rechargeable battery.
One of the things that a Mac will do is "requisition" power for each port and even device based on the total demands. For instance, I could plug in a single iPhone or iPad to my mid-2012 Unibody MBP, and I could check in System Report that it had reserved 2100 mA for it. But if I had plugged in two such devices, it would reduce the current available for each depending on which one was plugged in first. But it might be 1500 mA for the first and 1000 mA for the second. It probably gets a lot more complicated when there are 3-4 USB-C ports and then hubs and direct connections But it's not going to damage anything, but certainly if you've got a lot of devices it might not deliver maximum power to each device.
It depends on what you have connected. However, there really is no danger of overloading. The main issue would be if the demand is so high that the power supply can't supply enough and it taps into the battery for some power. I'm guessing your hope is that the battery is more or less unused. Using it doesn't "hurt" it any more than using the Mac normally on battery power, but any battery use inherently will result in degradation. That's just what happens with any rechargeable battery.
One of the things that a Mac will do is "requisition" power for each port and even device based on the total demands. For instance, I could plug in a single iPhone or iPad to my mid-2012 Unibody MBP, and I could check in System Report that it had reserved 2100 mA for it. But if I had plugged in two such devices, it would reduce the current available for each depending on which one was plugged in first. But it might be 1500 mA for the first and 1000 mA for the second. It probably gets a lot more complicated when there are 3-4 USB-C ports and then hubs and direct connections But it's not going to damage anything, but certainly if you've got a lot of devices it might not deliver maximum power to each device.
The devices will draw what they need; chargers don't "push" electricity. If their combined need is greater than the charger can supply, it can heat up.
As long as the batteries get the proper electricity, and the charger supplies that, batteries will not be damaged. But as you add devices, power is diluted and it will take longer to charge any given device.
Can you use your macbook laptop as a charging station while plugged in without hurting battery?
