Thanks for the ideas. On March 21, everything was ok. On March 22, the sleep/hibernate problems started. I hadn't installed any software between those times, and the only updates I got were to Windows Defender, which happens almost daily.
Before I read your reply, I had added Hyper-v to my SP3 to see how it responded in that scenario. I know Hyper-v doesn't support connected standby, and apparently it doesn't even sleep. The power options said that closing the lid or pressing the power button would put the machine to sleep, but instead it either powers off or hibernates, I couldn't tell. At least it wasn't chewing up the battery when it powered off. I left Hyper-v installed for a day, and then last night I removed Hyper-v, but not until a system firmware update was installed.
Anyway, my SP3 now goes into connected standby with no issues, and hibernates after 4 hours. There's really no way to tell whether it was installing and removing Hyper-v that fixed the problem, or the firmware update did. I suspect it was the Hyper-v install/uninstall. Thanks again for the help! Here's the latest sleep study information:
Connected Standby Session 12
| 12 | 2015-03-27 09:08:30 | 4:00:42 | 2,101 mWh | 5% of battery | 524 mW | Drain | 98% | HW: 98% | ⋮ |
|---|---|---|---|---|---|---|---|---|---|
| IR TRUNCATE PERCENTAGE | 60% |
|---|---|
| PEP PRE-VETO COUNT | 0 |
| PEP VETO COUNT | 0 |
| CS | 100% | 4:00:26 | 0% | 0:00:00 | 0% | 0:00:00 | 0% | 0:00:11 |
|---|---|---|---|---|---|---|---|---|
DRIPS Histogram
Percent of time spent in DRIPS bucketed by time interval length
Top Offenders
Top 5 offenders, ranked by active time
| Disk drive (\_SB.PCI0.SAT0.PRT0) | Fx Device | 1% | 0:02:42 |
|---|---|---|---|
| Marvell AVASTAR Wireless-AC Network Controller | Networking | 1% | 0:02:30 |
| CPU C0 Time | Processor | 0% | 0:00:43 |
| Intel(R) HD Graphics Family (\_SB.PCI0.GFX0) | Fx Device | 0% | 0:00:06 |
| Maintenance Phase | PDC Phase | 0% | 0:00:05 |