Do you turn wifi off to save battery?

[filmo]

I don't think it is ever totally off until no battery power. Seems to have clock keeping time while off that checks for news paper subscriptions.

[robko]

Just to clear up some potential confusion here: with the older Kobo Wifi (as opposed to the Kobo Touch) there was the option to have the Kobo wake up and automatically download your newspaper in the morning. This could eat a lot more battery for people who didn't have any newspaper subscriptions anyway, so it was recommended to turn this off. The Touch does not have this option at all. Powering the Kobo off would prevent this from happening (you had to leave it in sleep mode). Putting the Wifi in airplane mode (as mentioned previously on here) is the equivalent of turning it off. Yes there must be a tiny amount of battery being used to keep the time, but I can say from experience that my Kobo Wifi in powered off mode will last for several months or more with no appreciable change in power level on the battery (I use my Touch these days).
With the Touch if you don't have the wifi in the airplane mode, you'll notice it automatically connects and updates your bookmark positions when you open/close a book (at least I assume that's what it's doing) so it will use more battery.
And power off puts the whole unit into power down mode. The screen is pretty much in power down any time it's not changing something on it. When the unit is not powered down it is using energy to maintain the data in the volatile memory (the book you have currently loaded to read as opposed to the books stored in the non-volatile long term memory) and polling the touchscreen waiting for touches.

[vice-versa]

I let the wifi on and set sleeping mode after 5 minutes and off after 10 minutes. I would estimate my time between to charge about a month. I noticed that the wifi connected only when I ask my kobo to sync or when I download a book (in fact, as I manage now my books with calibre, I don't download books by wifi anymore).

[jusmee]

Originally Posted by robko

And power off puts the whole unit into power down mode. The screen is pretty much in power down any time it's not changing something on it.

Yes, that's why the "Power Off Screen" option didn't make sense. I guess they have to mean power off device.

Also, most microprocessor chips have a sleep mode where they consume virtually no power. If, as people have said, true power off makes the Kobo touch battery last longer than sleep mode, I have to wonder if Kobo have implemented it properly. On my last reader, inaction let the processor go to sleep mode and battery lasted just as long, and there was never any need to power it off. Using it was more like a real book, you just put it down somewhere until you were ready to start reading again. Given that extra time to power on/off and the time it takes to boot, I wish the Kobo had a true sleep mode too.

[jusmee]

Originally Posted by filmo

I don't think it is ever totally off until no battery power. Seems to have clock keeping time while off that checks for news paper subscriptions.

The clock chip should not be a significant drain on battery. Think how long a watch lasts on it's small battery.

I have trouble with seeing how it can wake up from power off to do anything like connecting to the internet via wifi. The operating system is NOT running, hence the boot-up sequence next time you turn it on. It can't do stuff when the system isn't running.

I even am surprised that it would do this in sleep mode.

[Koboyashi]

Originally Posted by robko

... and polling the touchscreen waiting for touches.

But in sleep mode, there isn't any touchscreen polling, since you can only wake up the KT via power slider. Regarding the absence of page turning and/or other actions in sleep mode this seems to be the only difference in power consumption between reading mode and sleep mode.

[jusmee]

Originally Posted by Koboyashi

But in sleep mode, there isn't any touchscreen polling, since you can only wake up the KT via power slider. Regarding the absence of page turning and/or other actions in sleep mode this seems to be the only difference in power consumption between reading mode and sleep mode.

Hmmm, then it's not really sleep mode, more like a screen lock top prevent accidental touches.

[Koboyashi]

Originally Posted by jusmee

Hmmm, then it's not really sleep mode, more like a screen lock top prevent accidental touches.

Yes, I think so. One could compare the battery life between sleep mode and reading mode (staying on a book page of course) in "Airplane Mode". Unfortunately I haven't the patience to figure it out Mostly I need my KT for reading.

[robko]

Originally Posted by jusmee

Hmmm, then it's not really sleep mode, more like a screen lock top prevent accidental touches.

I'm fairly confident that the processor "sleeps" to some degree even when you aren't in sleep mode. I base this on an issue I had with the original firmware (at least 1st firmware that added newspapers) on the Kobo Wifi with newspapers. Sometimes it would "time-out" and not complete loading until you pressed a button again, since the processor went to sleep before it finished loading. The biggest difference been reading and sleep would have to be the screen polling for touches since it's maintaining stuff loaded in memory even in sleep (not doing either in power off).
The bottom line is that regardless of the reasons: wireless on uses more power than airplane mode, sleep mode uses more power than powered off.

[The Terminator]

I wonder how much battery can be saved by turning full page refresh's down? Fairly easily you can set it to go past six.