How to avoid battery drain on MacBook Air while asleep

I have a MacBook Air, 13 inch, 2017, running macOS Sierra 10.12.6. I use it once or twice a week. I close the lid when not using it, and do not shut it down.

When I open the lid, it has lost more than 10% of battery capacity per 24 hour period.

Do I need to shut it down manually rather than closing the lid? That would require startup time for each use.

I have tried to reset the hibernate mode to 1, and it will not change from mode 3.

Any ideas?