The battery life on my Dell XPS 13, while never great, has gotten seriously bad lately. Using powertop, I've noticed that there seems to be some sort of USB device drawing quite a bit of power.
PowerTOP 2.6.1 Overview Idle stats Frequency stats Device stats Tunables The battery reports a discharge rate of 12.8 W The estimated remaining time is 2 hours, 2 minutes Summary: 377.0 wakeups/second, 47.0 GPU ops/seconds, 0.0 VFS ops/sec and 6.0% CPU use Power est. Usage Events/s Category Description 3.85 W 100.0% Device USB device: usb-device-0cf3-3004 3.58 W 40.0% Device Display backlight 1.81 W 2.5 ms/s 130.5 Interrupt PS/2 Touchpad / Keyboard / Mouse 1.13 W 17.5 ms/s 118.4 Process compiz 452 mW 16.0 ms/s 31.0 Process /usr/bin/X -core :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch 419 mW 9.4 ms/s 32.5 Process /usr/lib/gnome-terminal/gnome-terminal-server --app-id com.canonical.Terminal.swYIftfwqqbunjqoezwSzqxRaqPBMBqC 315 mW 676.0 µs/s 22.6 Interrupt  i915 294 mW 0.0 pkts/s Device nic:virbr0 165 mW 0.0 pkts/s Device nic:lxcbr0 144 mW 628.1 µs/s 10.3 Process nautilus -n 129 mW 111.7 µs/s 9.3 Process [rcu_sched] 112 mW 2.7 ms/s 7.5 Process /usr/bin/ibus-daemon --daemonize --xim
Problem is, I don't have any USB devices plugged into the laptop.
What would be my next step for figuring out how to identify the USB device using all this power?
Further research led me to run
lsusb which shows the following output:
Bus 004 Device 003: ID 0cf3:3004 Atheros Communications, Inc. Bus 004 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub Bus 004 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 003 Device 003: ID 1bcf:288f Sunplus Innovation Technology Inc. Bus 003 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
And some Google searching suggests that the problem device is related to my WiFi/Bluetooth module. Most of the forum posts I've found suggest that there used to be a problem with the drivers for this device but that if you're running the latest version of Ubuntu you should be good. I'm on Ubuntu 15.04 but still having problems so I'm not sure what my next step should be.