Have the Tesla phone app to show the amount of battery charge as a percent as well as the estimated range. Better still would be the projected range as well as a range based on the last 30 miles.
Unfortunately, the estimated range is not what is normally achieved and therefore can be misleading when planning journeys.
At the top of the app, it shows the range in miles, the same indicator as in the car. In addition, the battery charge graphic is shown. While the battery level not in a percent form, it’s easy to estimate. The charging screen shows a larger view.
I prefer to think in terms of "rated miles" instead of "% of battery". After nearly 70K Model S miles, I have not really needed to know percentage; just rated miles needed to get to the next stop. Besides, the battery bar itself is already a graphical version of the percentage.