using MBP charger on rMB?

[FilmIndustryGuy]

is it safe to use the MBP 16 charger on the 12 inch rMB which usually takes a 29w charger? Is it also safe to use the 29w on the MBP? Trying not to degrade batteries

 

[chabig]

You can use any charger. A charger is the source of power. The device being charged controls what happens with that power.

 

[bdj33ranch]

You will be OK. Responder chabig is correct. Here’s some additional info to help soothe your concern. I’ve used various Apple chargers rated at different wattages between my old, old MB and somewhat newer rMBP for years with no issues. I’ve intentionally bought higher rated chargers as replacements to give greater flexibility for future MBP purchases. The internal circuitry of your MB’s will only draw the amount of power from the charger that the computer is designed to accept. You may notice that your 12in will charge faster with the 16in charger. But it won’t hurt it. Be aware though that the 12in charger may not put out enough wattage to “keep up” with the power draw of the 16in. So you may see the battery level decrease while the computer is in use even though the charger is connected.

 

[evec]

USB-C PD charging all with protocol communicate between laptop and charger, so they will match and select best avilable power profile.
Higher rated Power supply is good running on low power need device. However, high power draw device use under-rated PD charger will not sufficent for full power draw, make the battery consume and power down if battery exhausted.