Should I set my laptop to sleep/standby or hibernate when the battery is nearly dead?

Question

I know the question seems very simple at a first glance, but please hear me out before responding. I did my own research, and want to hear your thoughts/opinions. If you don't care, and just want to see what I'm asking, see the points at the end of my post.

The primary reason for me asking this question here is to raise awareness - we all believe that the second our laptop power is in jeapordy, we must hibernate the system... Why?

To start, I am assuming that hibernation is basically dumping the system RAM and process states to the hard-drive, and shutting the computer down (ref). Resuming would simply load the RAM back from the hard drive - a somewhat time consuming process when compared to standby.

Standby is simply putting the system in a low-power state, providing just enough power to keep the RAM from erasing itself (ref).

Now, according to some websites, standby mode in the S3 state consumes next to no power. Even if the consumption was at "worst" (1.8W according to the linked website - which was for a desktop) in standby mode, this is nothing compared to my laptop's ~30W usage on idle (this figure was found by using HWMonitor). From these figures, it can be estimated that my battery will last roughly 17 times as long in this state.

Now, assuming that you have a battery that lasts about two hours, and you set the critical battery level to 3%, you would have 3.6 minutes left on normal consumption, or roughly 1 hour on standby. In most cases, you would have already saved your work if the battery level reached this critical level, regardless. I don't believe that the consumption of a laptop in S3 mode is even near 1.8W, the reason for this being my own test.

I have done a test myself, with two laptops of mine (a 6-cell battery Compaq, and a 9-cell battery Dell). In both, I ran them until the battery was at 3% and automatically entered standby.

I then turned on the machines again, rebooted them (just to drain the battery a little more), and manually placed them into standby. After leaving them overnight, without even plugging them in again, I turned them back on (~12 hours later), to find that all of my data was still there (long enough for me to grab my power cable and save what was on the screen).

Both of these laptops are just over a year old, which isn't too old... But the Compaq battery isn't very good, and lasts usually around 1.5 hours.

• Now, am I safe in assuming that I can completely disable the hibernate mode on my laptop, and just use the standby mode?
• Has anyone done any tests like this in the past?
• Does anyone know advanced, detailed power consumption of desktops/laptops in S3 mode?
• Has anyone else tried something like I did and found similar/different results?
• Are there any disadvantages (or advantages that I'm unaware of) to using standby over hibernate?

Answer 1

Yes, you can completely disable hibernation with no ill affects, in my experience.

One disadvantage of this is (at least) two things that you can do with hibernation that you cannot do with standby.

1. Completely remove power (no power cord or battery)
2. Hibernate and reboot to another OS (in a dual boot situation)

Both of these are rather uncommon, but I have done #1 at times, mainly to switch batteries or to examine my battery. #2 I do quite often. I use Windows for my job and Linux for everything else, and it is nice to just stop what I am working on at home and not have to worry about losing things.

Answer 2

If you're just going to leave your laptop on top of a table then I guess, at least according to your experiment, it's perfectly fine to have the computer go on stand by instead of hibernating/shutting down at some critical battery level. However, I think if your laptop will have to go mobile (for example you'll have to pack it in a bag and bring it elsewhere), I think your best option would still be to let it hibernate or shut down. If your battery comes lose, you will lose everything in memory.

Answer 3

am I safe in assuming that I can completely disable the hibernate mode on my laptop, and just use the standby mode?

Yes.

You have just complete the experiment and it shows it is ok. Think you are ok to proceed.

_{Let us know in two months how is that strategy going}

Answer 4

Well, my opinion is that such tests are nice in the lab environment. But as the batteries slowly wear out 3% will be less and less time. But are you willing to bet your data that Sleep mode will last enough time?

If you are (or if stuff you're working on is not so valuable), just disable hibernation. But if not, why not put PC in hibernation when you need it?

This question is also very subjective and... not needed? I mean, disk space is cheap, why saving it on hibernation? If you don't need hibernation you simply don't use it. But if situation arises, hey - there's hibernation.

The only drawback I see is possible problem with waking hibernating laptop. XP had such problems, Vista very few and Win7, I expect, virtually none. Linux hasn't got problems waking from hibernation as far as I know. But if you did have such problems, you would simply turn hibernation off, without much discussion. Right? ;)

Answer 5

If you're travelling from one side of the world to the other you might want to have Hibernation enabled, as you can't guarantee being able to find somewhere to plug your laptop in between flights.

So it really depends on what you're doing and where you're taking your laptop as to whether or not you should disable hibernation, or leave it enabled.

Answer 6

Another minor advantage of hibernate over standby: If you do full disk encryption, hibernate is also more secure than standby, since the crypto keys are stored in memory during standby.

Answer 7

One problem I hit with my laptop is sometimes the lid comes open a bit in the bag and it wakes up, chewing up lots of power without me realizing.

I have read that hybernate requires a button press to wake from, whereas sleep wakes up by opening the lid only - although other articles indicate this is laptop hardware specific. My laptop (Dell Studio XPS running Vista Business Edition) appears not to give me the option of pressing the power button to wake from sleep mode. But the only hybernate I have found is when the battery reaches "critical". However, the times the battery has gone dead flat the laptop failed to restart, indicating the hybernate failed to work.

My point - opening the lid may be another factor to consider when chosing between hybernate and sleep, but it may be specific to your hardware/OS version.