How to view MacBook power usage while unplugged

Yes, and that is a tremendous waste of your time and personal energy.

That computer is a battery-CAPABLE device, It is not optimized as a battery-operated device (it is not an iPhone.)

Your computer performs best when connected to AC power, such as the power adapter. It can use the full output of the Power Adapter AND when doing especially challenging work could also freely "borrow" power from the battery. In some cases, even with the power adapter connected, the charged state may decline during very stressful work.

When used only on battery, your computer has no extra cushion of power, and may perform more slowly. However, for ordinary non-stressful tasks this may not be objectionable (possibly not even noticeable.)

In general, you should ALWAYS connect a power source when it is possible to do so, and only run on batteries (which could be somewhat slower) when no power sources are at hand. Modern Macs maintain optimum battery charge levels under program control, and will NEVER over-charge. Connected to Power is NOT necessarily charging.

When you set it down in one place, or set it down for the night, Plug it in. Then you won’t CARE whether it would drain the battery.

head_unit wrote:

I should have posted that I sometimes use it in the car and want to power it because I forget what, it was low or something. I tend to use the MBP at a table not too near an outlet, then when not using it leave it plugged in in the kitchen.

I'm wondering if 30W PD is enough...but I am also just curious to see how much power it is using.

I would not expect most car charger adapters to do more than slowly charge the laptop while it is powered off. I think the most powerful charing adapter for a cigarette lighter adapter I found several years ago was only capable of about 70W with PD and was from Satechi (may be fine to actually run some smaller laptops). I wasn't impressed by most others.

At best completely powering off the laptop will allow the 30W power adapter to slowly charge the laptop. If you just put the laptop to sleep, then you may find it will charge even slower plus you would likely need to put the laptop back to sleep since connecting a power adapter will wake up the laptop.

If you will find yourself having no options except to have the laptop on battery for extended periods of time, then you may want to look into a Power Bank made for use with laptops. Here is one article show casing some options:

https://www.engadget.com/computing/accessories/best-laptop-power-bank-120040388.html

As @Grant mentioned, keep the laptop connected to power whenever you can so when you need to be away from power outlets you should have enough battery charge to operate the laptop for some hours. If you know ahead of time you will need the laptop to run on battery for an extended amount of time make sure the battery is at 100% charge....if charging is paused at 80%, then click on the battery icon & select "Charge to Full".

<< I'm wondering if 30W PD is enough. >>

Probably NOT. The currently-for-sale MacBook Pro 14-in ships with a 70 watts power adapter. That is the smallest I would recommend you use to run your Mac. any lower, and you may risk draining out the battery while using it.

<< I tend to use the MBP at a table not too near an outlet. >>

then I recommend you buy the Apple Power adapter AC extension cord, to get two meters closer to an outlet. This is the US version: