[Nexus 4 Q&A, Help & Troubleshooting] FranzBier:
I made an interesting find in the kernel logs of my phone.

Not sure, but i will post a short piece:

<6>[28051.217025] PM: suspend exit 2012-12-04 19:41:46.156162395 UTC
<6>[28051.217117] suspend: exit suspend, ret = 0 (2012-12-04 19:41:46.156284372 UTC)
<6>[28052.152414] hdmi_msm hdmi_msm.1: HDMI HPD: event detected
<6>[28052.152536] hdmi_msm hdmi_msm.1: HDMI HPD: QDSP OFF
<6>[28052.153024] hdmi_msm hdmi_msm.1: hdmi_audio state switched to 0: hdmi_msm_hpd_state_work
<6>[28052.153116] hdmi_msm hdmi_msm.1: Hdmi state switched to 0: hdmi_msm_hpd_state_work
<6>[28052.153268] hdmi_msm hdmi_msm.1: HDMI HPD: DISCONNECTED: send OFFLINE
<6>[28052.823221] suspend: enter suspend
<6>[28052.823435] PM: suspend entry 2012-12-04 19:41:47.762002847 UTC
<6>[28052.823709] PM: Syncing filesystems...
<4>[28052.826426] Freezing user space processes ... (elapsed 0.03 seconds) done.
<6>[28052.890000] sync done.

As you can see, the device is sleeping. then it exits suspens, just for some HDMI stuff (which is not connected to the phone). After this. it goes to sleep again. The interesting thing: BatteryState said in this complete log, there should be 14 wakelocks of msm_hsic_host, but i just found 1

<6>[28049.121527] suspend: exit suspend, ret = 0 (2012-12-04 19:41:44.061334684 UTC)
<6>[28049.121619] active wake lock PowerManagerService
<6>[28049.121741] active wake lock msm_hsic_host
<6>[28049.121802] suspend: abort suspend
<6>[28050.052429] hdmi_msm hdmi_msm.1: HDMI HPD: event detected
<6>[28050.052582] hdmi_msm hdmi_msm.1: HDMI HPD: QDSP OFF
<6>[28050.053375] hdmi_msm hdmi_msm.1: hdmi_audio state switched to 0: hdmi_msm_hpd_state_work
<6>[28050.053528] hdmi_msm hdmi_msm.1: Hdmi state switched to 0: hdmi_msm_hpd_state_work
<6>[28050.053680] hdmi_msm hdmi_msm.1: HDMI HPD: DISCONNECTED: send OFFLINE
<6>[28050.822305] suspend: enter suspend

Again in combination with the HDMI stuff. I will compile a kernel without the HDMI driver and then lets see if i can raise battery life.

Problem here: i could hardly find 14 hsic wakelocks in this log. But this hasn't to say anything, as its not sure if they all log in this file,

In other logs i found some hsic wakelocks, but they dont seem to stop the device from going to sleep. For example see here:

<6>[26776.471871] active wake lock msm_hsic_host
<6>[26776.471962] active wake lock sns_async_ev_wakelock
<6>[26776.472023] PM: Syncing filesystems...
<6>[26776.478219] sync done.
<6>[26776.563249] pm8xxx-led pm8xxx-led: resume red set 0
<6>[26776.563401] pm8xxx-led pm8xxx-led: resume green set 0
<6>[26776.563584] pm8xxx-led pm8xxx-led: resume blue set 0
<6>[26778.364653] suspend: enter suspend
<6>[26778.364653] PM: Syncing filesystems...
<6>[26778.365171] PM: suspend entry 2012-12-04 19:01:14.130533725 UTC

Device goes to suspend even if there is a hsic wakelock active.... i will make a deeper dive into this and lets see what we can find...

P.S. every couple of seconds the device goes active for

event0-572:

<6>[28037.160380] wakeup wake lock: event0-572

<6>[28047.558762] wakeup wake lock: event0-572

<6>[28051.151986] wakeup wake lock: event0-572

<6>[28053.190228] wakeup wake lock: event0-572

and so on. Im sure that a couple of seconds are nothing for the battery but i may sum up. Lets see if we can find whats event0-572 is