What is the minimum power adapter rating required for a 14" MBP with M1 Max, if you don’t care about fast charging?

I was able to come up with my own measurements to answer this question. I remembered that I had a device called a "Kill A Watt P3", that plugs between an electrical outlet and an appliance plug. It can give real time power consumption data. I plugged my Apple 96W power adapter into this and my 14" MacBook Pro with M1 Max, 64GB of memory, and 24 graphics cores (i.e. a nearly maxed out system) and took power measurements:

Battery 100% charged, power readings varied, the ones below are the peak powers observed

Lid closed. 5 W

Waking up, screen 50%: 14 W

Screen off: 9 W

Screen 50%: 11 W

Screen 100%: 18 W

Single core GeekBench 5: 24 W

Multi core GeekBench 5: 53 W

Battery 5% charged (i.e. fast charging)

Awake screen 50%: 96 W

My tentative conclusion is that even a maxed out 14" MacBook Pro should operate fine with a ~60 W + supply. Obviously fast charging will be limited by the power supply. There will be power transients that a device like the one I used will miss, but the battery should handle those fine if it has any charge at all. This means that it is likely that a pass through hub limited to 60W or one of the travel sized GaN 66W USB C supplies, should power any 14" MacBook Pro.

I hope to test this soon, or hear from someone who has.

Love it when people don’t know the answer, so their answer is “why would you want to do that…”

One reason would be: to use the M1 Max Mac with a single cable Thunderbolt dock, you need to know the pass through power required.

Thanks for the info. I’ve now had the opportunity to use my 14” M1 Max with 4 different USB-C PD power adapters. Tried both the Apple MagSafe 3 power cord and a 60 W rated USB-C rated cord.

20 W (supplied with Apple iPad): barely kept up with light email and browsing. Slows battery discharge and should be able to recharge a turned off MacBook overnight.

30 W (Anker GaN ultra slim) slowly charged battery during light use: email, browsing, app install.

66 W (Anker GaN about the size of Apple 20 W) seems to charge batteries and keep up with any of my use. I’ve only had the fans come on quietly and briefly. Charging speed seemed comparable to my old Intel MBP.

100 W (Apple supplied) Will fast charge the M1 Max 14.

My conclusion is that many USB C chargers with PD (power delivery negotiation support) may be helpful in a pinch. The tiny Anker 66 W GaN charger will be my regular travel charger. Most docks with 66 W + pass through should be fine as well. Remember that as long as your supply is adequate most of the time, your laptop battery will take the peak loads. If you run your fans all the time or need fast charging, I’m sure you know it and should stick with an Apple 100 (or 130) Watt supply.

USB PD is new, we all know how reliable USB hubs are :-( …. So YMMV and some power supplies that should work won’t.

Thanks for the info. Your observation about the potential for pulling power from the battery as well is quite correct, but probably not an issue here. I should have been clearer that the 96W charger was used. With all the measurements so much below that (except for the rapid charge), it is unlikely that power was pulled from the battery in the other cases except for brief transients.

Not sure how well the new MBP deals with supplies that don’t support PD negotiations. Is obviously an advantage for the laptop to know ahead of time how much power the supply can provide ahead of time. It seems to be well behaved when this isn’t enough and will draw down the battery for needs in excess of the supply. Next time I draw my battery down below 50% I’ll verify if it will fully charge from an iPad 20W adapter.

OK, I ran my MBP 14 A1 Max down to 25% battery charge. I hooked up an Apple 20W USB charger and started it recharging. I closed the lid to sleep the MacBook and then opened it for a quick check about every half hour. The MacBook was fully charged in about 4 hours and 15 minutes. A full charge should take less than 6 hours for the 14". Scaling up I'd expect the 16" to charge in about 8 hours from the 20W supply.

With anything other than light use, I'd expect to loose battery charge slowly with the 20W charger plugged in. If you can get through a full day on battery power, you should be able to keep on going with overnight recharges with the 20W charger indefinitely.

Presumably the Macbook requires some minimum amount of power, negotiated with via the USB C PD 3/3.1 standard to draw any power. It would be good to know ...