Internal battery, that is wall rechargeable.
As a backpacker every ounce counts so extra batteries for me are a down fall for this satellite messenger. I’d like to see an internal battery with an external charging port that I could recharge with battery bank or solar panel.
If my spot finder could be charged in my truck I could leave it there and it would be ready when I need it. Now I have to keep it indoors during the cold weather to ensure the batteries are charged. I occasionally forget to take it (Old age brain malfunction) when headed for the woods.