When and how long I need to charge my laptop?

Man, that question is a can o' worms. It's all about how many battery cycles you go through. Batteries have a limited amount of charge cycles, then their performance suffers. Modern MacBooks use lithium batteries with an estimated 1000 battery

cycle life. If that's to believed, and there is no adverse effects of having the battery plugged in at all times, you may as well keep it plugged in.

To find the battery cycle count on your MacBook Pro:

• Hold the Option key and click the Apple  menu. Choose System Information

• Under the Hardware section of the System Information window, select Power. The current cycle count is listed under the Battery Information section.

If you think you might ever sell the Mac and get a newer model, then I highly highly suggest keeping it plugged in as much as is possible. That is so your battery cycle count stays low (people certainly look at that, for good reason).

Personally, I purchased another charger so I can keep it charged when I swap rooms etc.

Here's a good article:

https://support.apple.com/en-us/HT201585

I get it. That's why I said "that question is a can o' worms" in my reply! There are many factors that can effect battery life. Environmental conditions, heat, charge cycles, voltage fluctuations in your power source, etc. That all said, abused MBPs may have batteries that last way beyond the 1000 charge cycle estimation, but a home-kept MBP battery may fail well before 1000 cycles.

Keep it plugged in. Use an Apple charger. Use a surge protector. If your an electronics snob, use a power conditioner!

I hope my reply was of some use to you.

peace

~( ):>

An easy to follow rule of thumb:

If you are near an AC outlet, leave it connected to the charge circuit.

If you need portability, use it on battery power.

Also:

https://www.apple.com/batteries/maximizing-performance/