Is it reasonable to hack the PW to be a long life clock?

[NiLuJe]

You'll probably also want to switch to the powersave CPU scheduler. It probably won't help all that much, but, eh.

[mattzz]

Originally Posted by Junket

PW4 has a 1500 mAh battery, PW/2/3 are usually said to be 1420 - 1470 mAh. If you can suspend a significant amount of time as several posters suggest is possible to set (above, here) & minimize wifi use, a month or more on battery should be an attainable goal.

The math still does not check out, even if you spend a considerable amount in STR (like ~90%).

I am using the Kindle as a clock device only (I know, sounds weird - but hey...) which updades the display every minute and does nothing else.

The device will be in STR state for ~55 seconds each minute and active for about 3-5 seconds. 5 seconds consuming 100mA for 60 times an hour results in ~8mAh. So IN THEORY the best we can get is a runtime of ~200 hours. And that is not taking account for any wifi reconnects/updates. So even in best case I think we are far away from a attaining a runtime of a month.

Different story for an hourly update (~50 days runtime) but I guess for a clock the user acceptance factor would drop quite severly. ;-)

So from my understanding the 1440 rtc wakups per day are killing the idea of a long life battery clock.

Creating the header below should forestall aggressive checks for firmware updates when wifi is enabled:
touch /var/local/system/SKIP_UPDATE_CHECK

Does this also work for an old PW running 5.4.3.2?
I added todo-g7g.amazon.com to my /etc/hosts, pointing at 127.0.01...

Better yet to stop the todo process next to lab123_gui and other processes that are not needed in my case.

Setting the cpu governor to powersave also reduces current draw (from ~110mA with "ondemand" to 50-80mA with "powersave" according to gasgauge-info) but things will take longer then.

[NiLuJe]

"things" should be fairly tame for a clock, I wouldn't expect that to be a net loss (for this specific use-case).

[handyguy]

I actually slow the updates down at night to every 10 minutes - nobody's around to see the clock anyways... Also, wifi connect/ntpupdate could be slowed to weekly without ill effect on a clock that is only displaying minutes and not seconds.

[JSWolf]

Originally Posted by handyguy

I actually slow the updates down at night to every 10 minutes - nobody's around to see the clock anyways... Also, wifi connect/ntpupdate could be slowed to weekly without ill effect on a clock that is only displaying minutes and not seconds.

Why not set the clock to go off all night when you are asleep?

[Junket]

There are an endless number of power-centric optimizations that could be made. Do you sync the time once an hour, four times a day, once a day, etc? Do you need the clock to always be spot on or are you insensitive to a few minutes drift? Power save scheduler, perhaps you are willing to halt updates outside of an active hours schedule e.g. when sleeping as suggested earlier.

If your Kindle will be serving as a clock at a fixed location one could have a motion detector trigger the clock to update only when someone walks into or is active in a room. The motion detector could drive an electromagnet to trigger the hall effect sensor (same as a smart case).

Are you willing to set the Kindle in a cradle where power use is no longer an issue? And so on. There are scenarios where you might only get 5 or 7 days on battery. And others where a month should be possible. And enough variables that you might as well do some empirical testing to get accurate run time figures.

[handyguy]

Originally Posted by JSWolf

Why not set the clock to go off all night when you are asleep?

It's a compromise, might be up late, need the time... Hopefully the suspend etc. will more than make up for it.

[DuckieTigger]

Originally Posted by handyguy

It's a compromise, might be up late, need the time... Hopefully the suspend etc. will more than make up for it.

Or a sufficiently large enough powerbank. Then you can afford to update every minute even at night.

[rem736]

Originally Posted by DuckieTigger

Or a sufficiently large enough powerbank. Then you can afford to update every minute even at night.

i have no issue with keeping it plugged in 24/7. so i'm not worried about power saving at all. as it is, e-ink screens are the least power hungry screens available.

as an alternative, i currently use an old android phone with a clock app set with always on display. there's no sim card and it's connected to my home wifi. it's also constantly plugged in for power. i use "Big Digital Clock" by andreas1724 (free on the google play store and currently at version 1.1.1) for this purpose. it's also ad free. no more adjusting any clock in the house twice a year to get the time right.

i'm not the developer nor am i promoting this app in any way. i just like it because
1. it's free
2. it's ad free
3. display color is completely customizable (not limited to a few pre-determined colors)
4. it's simple (just displays the time, 12/24 hour with or without seconds).
5. it will also prevent the screen from going to sleep (blacking out).

[DuckieTigger]

I see. Also survives a power outage — the other reason to reset clocks.

[handyguy]

Here's my current version of the Kindle clock. It does not have any Kindle power optimization yet.
To make it work:
1) Unzip and copy the files to /mnt/us/extensions/clock.
2) Update the email info in emailbat.py if you want to be notified of low battery
3) Update the fonts in c2.py to something on your device and un-comment out the emailbat.py code section
Press the new Clock button in KUAL or from the command line:
python c2.py

I don't pretend to be the greatest coder, but the code is relatively modular and commented.

[Junket]

So that settles the question in post no. 1
Thanks for sharing.

[handyguy]

oops, forgot to mention I manually disable the screensaver:

lipc-set-prop com.lab126.powerd preventScreenSaver 1

[handyguy]

I have changed from using python sleep to using rtcwake; battery is now lasting an estimated 8 days (from 3+ with sleep.) Still not the order of magnitude improvement I was hoping for. I will be fine tuning the code, but that is not likely going to get me to the 2-4 weeks I would like. Will report back.

[rem736]

Originally Posted by handyguy

Here's my current version of the Kindle clock. It does not have any Kindle power optimization yet.
To make it work:
1) Unzip and copy the files to /mnt/us/extensions/clock.
2) Update the email info in emailbat.py if you want to be notified of low battery
3) Update the fonts in c2.py to something on your device and un-comment out the emailbat.py code section
Press the new Clock button in KUAL or from the command line:
python c2.py

I don't pretend to be the greatest coder, but the code is relatively modular and commented.

would this work on any kindle? or just the PW?