I haven't been below 10% on the internal battery since I've been using smart power. Next time I am low I'll see what happens. I do know that the range extender set to discharge first with Smart Power works the same. Below 10% it reduces power and at 5% it switches to the internal battery. I do have the remote set so it can disable smart power with a button press. So if I do get the main battery below 5%, I'll be able to switch between smart power on/off and see if actually does enable draining the main battery below 5%.
Sounds like you have smart control set with just the basic settings. If you enable expert mode (top right menu hamburger), there will be more options which include setting different thresholds for smart hr and smart power. Allows to adjust min/max assist levels for each eco/sport/turbo mode as well. This might prevent the low levels of assist you sometimes experienced. If I set eco to 19-98% range I always have a min 19% support in eco.
Sounds like you have smart control set with just the basic settings. If you enable expert mode (top right menu hamburger), there will be more options which include setting different thresholds for smart hr and smart power. Allows to adjust min/max assist levels for each eco/sport/turbo mode as well. This might prevent the low levels of assist you sometimes experienced. If I set eco to 19-98% range I always have a min 19% support in eco.