"Until recently if you had an off-grid system such as a street light and there was bad weather for more than a few days, the battery would drain, and eventually the light would go out. That’s it! There was no way to predict how long the battery might last, or to change the settings to preserve power. It’s like driving a car with no warning light on the dashboard to indicate when you’re low on gas."
Read the articleat North American Clean Energy.