This would be a very nice feature! Just got the Steam controller and love it so far :) Thanks Valve!
It would be nice if there was a generic battery indicator comparable to the battery indicators in other desktop environments, so all sorts of batteries could be shown, not just the steam controller, particularly laptop batteries and bluetooth controllers.
For the kernel part of this HID_BATTERY_STRENGTH reads as "This option adds support of reporting battery strength (for HID devices that support this feature) through power_supply class so that userspace tools, such as upower, can display it." and is available as an option in brewmaster's kernel version.
Just to update the report - this can be usefull for other controllers as well. Not needing to be SC specific.
Also there are some other nice ideas discussed here:
https://steamcommunity.com/discussions/forum/10/3203744275144591740/
Nothing extracted yet.
It would be handy to see battery level indicators in the Big Picture overlay, so we don't have to quit out of a game to see if the battery is getting low.