MacBook Pro (16-inch, 2019) Battery Drain While Charging

Your screen dump shows an 87 watt Power Adapter (MBP 15 inch type) that is only outputting 60 watts of power (non-Apple Type-C power cable?). That would explain the battery draining effect. As previously stated in this thread, the MBP 16 inch comes with a 96 watt PS and by using the supplied Type C cable (Apple brand) from that power supply directly to a Type - C port on your MBP (i.e., not through an Apple USB-C to Digital AV adapter which limits the power to 60 watts) you should have approximately 96 watts (mine indicates 94 Watts) indicated.

MacBook Pro 2019

I have also noticed the battery discharging when teaching a 1-2 hour class using Zoom with three external monitors connected to my MBP (clamshell mode). My setup includes the 96-watt power supply connected through an Apple USB-C to Digital AV Adapter. Based on what was posted in these threads, I discovered that the Apple USB-C to Digital AV adapter, which I use to connect one of the monitors and the original 96-watt power supply (previously mentioned), only passes 60 watts of power! Once I connected the power cord to the MBP directly, it increased to 94 watts (although my MBP identified it as a 96 watt PS). Time for a longer HDMI cord so I can have the power supply connected directly to the MBP and the Apple USB-C Digital to AV Adapter on a different USB-C port. Thanks to all for helping solve this issue.

Take away: The Apple USB-C to Digital AV adapter will only pass 60 watts of power.

Thanks. i realized i was using a 2017 mbp cable on my 2019! it was limiting me to 60W. i found my other cable and it got me up to 96W. Looks like the best way to ensure this is buying genuine apple

I've learned more about the problem.

I'll start with a reminder that all hardware described here was purchased new directly from Apple as a custom build.

When the charger is plugged in to the left rear USB-C port of my MacBook Pro, it is identified properly as a 94 watt charger. The MacBook Pro charges and operates as expected. I haven't seen any power management problems while using this port.

However, if the Apple charger is plugged in to the right rear USB-C port of my MacBook Pro, the MacBook sometimes identifies it as a 60-watt charger. When this happens, the MacBook has problems with power management. During periods of moderate use, the battery will start draining. This can continue until the state of charge goes so low that the MacBook puts itself to sleep. Even when applications are closed and the computer is idle (CPU use less than 3%), the MacBook may not attempt to charge the battery. When I unplug and reinsert the USB-C cable, the MacBook will start charging.

It's interesting to consider that I've seen this same behavior on two MacBook Pro 16" computers, both purchased directly from Apple within the past 60 days. Both had problems when power was supplied to the right rear USB-C port.

I had the same problem with a 13" MBP. The video cards use more power than the 60W set up I had can provide which means you discharge the battery when you plug monitors in.

The cure is using the 96W charger and the Apple 100W USB-C cable. Has to be BOTH to fix the issue.

The cable serial number lets you check what rating it is - you'll need a magnifying glass to find it though, small and light grey, not easy to see on the cable.

There are variety of cables available. Using the wrong one can cause problems.

Apple sells a Thunderbolt 3 cable rated to 100 watts. This can be used to maximally charge the 16" new Macbook Pro (the Mac laptop that presently requires the most watts) and it can also transfer data at up to 40 Gbps (10 Gbps when used in a USB 3.1 Gen 2 interface).

Apple currently sells a USB-C charge cable that will work with the 96-watt power supply on a 16" Macbook Pro. However, older USB-C cables may be rated to a lower wattage, and hence would not properly charge a 16" Macbook Pro 2019.

Third party cables should be scrutinized before purchase to ensure that they are rated to the right wattage and/or data transfer that you expect or need.

The power adapter is 60 W ?

The 16" MBP ships with 96W.

With the Mac plugged into the main, under a heavy load it will draw additional power from the battery.

Hello spyderdsn, 

Welcome to the Apple Support Communities. From your message I see that you have noticed the battery level drops while the MacBook Pro is in use and connected to the Apple power adapter. 

Based on the screenshot from System Information it appears that the USB-C power adapter was not charging at the time the screenshot was taken. If it was connected, check the battery status by holding down the Option key and clicking on the battery icon. This will show the battery status menu which includes the health of the battery, and if the Power Source is the battery or the power adapter. 

If you have the power adapter and the Power Source is showing that it's the battery, you'll want to follow the steps under, "My battery isn't charging" from this article: About Mac notebook batteries. 

All the best. 

Under 10.15.5, the new Battery Health Management (see Energy Saver System Preferences) if turned on, which it is by default, about once per day, if a laptop is left plugged in to the charger all the time, will slowly discharge the battery from 100% down to 90%-92%, then rapidly charge back up to 100%. This is to prolong the battery life (lithium battery), versus leaving it attached to the charger at close to 100% and not discharging. If you see this pattern, it is apparently normal.

If you see the charge drop below, say 89%, even while connected to the charger, that would be not normal, as far as I know. Apple has not provided a lot of documentation on this. But the 100%=>90%=>100% cycle, about once per day, is what I have observed with two new Macbook Pro 16" devices.

If you interrupt this cycle and reboot the computer, I believe it "resets" and charges right back up to 100% after the boot.

To get more than 60 watts over USB-C you need to use special USB-C PD (Power Delivery) cables. They should be labelled as Power Delivery. Normal USB-C cables are 60 watts max.

Not always Steve.

When playing a game, the 16" macbook pro might use more power then the charger can provide, resulting in battery drain while powered.

As far as I know the Battery Health Management option has not effect on this specific behaviour

I have this problem with a brand new 2019 MacBook Pro 16". I bought the computer direct from Apple. I am using only the Apple-branded charger and cable that came with the computer.

The laptop is always plugged in. During the night, the computer runs a backup that takes several hours. Although the laptop is plugged in to the charger, the battery drains down to 20% or so. In the morning, the menu bar will indicate that the battery is not charging at all.

The SMC has been reset several times. I have reinstalled the OS several times, using both Recovery and Internet Recovery.

Apple support told me that the only remaining step is to send the computer in to have the motherboard replaced. The customer service rep advised against doing that, saying that I should return the computer for complete replacement instead.

I now have a new 2019 MacBook Pro 16" which just arrived from Apple's factory in China. It has exactly the same defect. I have reset the T2 chip several times and reinstalled the OS several times, but the problem persists.

It's quite clear that the problem is not due to off-brand chargers or cables. It seems likely that there's a firmware bug here.

Apple will probably realize this and fix it in the future. Note that large corporations are very resistant to learning about problems with their products, so it will likely take many months and quite a few complaints before this comes to the attention of anybody at Apple with any decision-making authority.

sophieogle wrote:

I have this problem with a brand new 2019 MacBook Pro 16". I bought the computer direct from Apple. I am using only the Apple-branded charger and cable that came with the computer.

The laptop is always plugged in. During the night, the computer runs a backup that takes several hours. Although the laptop is plugged in to the charger, the battery drains down to 20% or so. In the morning, the menu bar will indicate that the battery is not charging at all.

I now have a new 2019 MacBook Pro 16" which just arrived from Apple's factory in China. It has exactly the same defect. I have reset the T2 chip several times and reinstalled the OS several times, but the problem persists.

It's quite clear that the problem is not due to off-brand chargers or cables. It seems likely that there's a firmware bug here.

Apple will probably realize this and fix it in the future. Note that large corporations are very resistant to learning about problems with their products, so it will likely take many months and quite a few complaints before this comes to the attention of anybody at Apple with any decision-making authority.

What is your setup? What is connected to your Mac (you indicated a backup external drive, what model/make is that drive)? Is your power supply connected directly to the laptop, or does it go through an adaptor or a monitor? Are you going through a power strip or UPS? Is your AC power stable or reliable?

The reason I ask is that these things can all impact your situation.

Keep in mind that many thousands (maybe tens of thousands) of users are using these Macs and not experiencing a discharge down to 20% when using external drives or games. So something seems to be different about your situation or setup. It is possible that you have two defective Macs in a row, but the likelihood of that seems low. It can be like a detective hunt to track these things down, however, I believe you when you say this is happening.

I believe that the laptop with original cables and power supply should be able to handle the load. We have two of these 2019 Macbook Pro laptops and frequently use them to make "clones" from one external drive to another, in other words two external drives are connected and we are copying large (up to 4 TB) amounts of data from one external drive to the other over an extended time period of ~ hours. Also used in the manner you are, backing up from laptop to a different external drive (we use both mechanical spinning drives as well as SSDs). I have also done Time Machine backups of the laptop at the same time as "cloning" the drive, e.g. multiple drives connected and working all at once. On these units, I have never seen a discharge as you describe when plugged in.

Can you describe more precisely your setup? Are you using a different power supply and cable from the first unit that did not work properly?