Power & Source of Big Ideas

Fix for Battery Saver mode /Sleep mode?

Moderators: chensy, FATechsupport

Dear fellow hackers/developers,

Anyone know a way to put te T4 (Android image) in battery saver mode/ sleep mode?

It's normally a standard feature of Android 8.x.x that is configureable, however the latest android ROM from FriendlyElec has the option 'Settings>Battery> battery saver mode' grayed out in the settings menu (cant switch it on)
'Settings>Battery> sleep mode' is not greyed out but is equally nonfunctional.

I'm using the T4 with a hdmi touchscreen displays and this issue is causing burn-in.
I feel like the absence of this base feature also causes the board to consume alot more power then it should on android.

Anyone have a clue how this can be fixed/circumvented?
@Developers: Can this be adresssed in the next android image?

Thanks in advance for your advice,

Hi Joe,

Have you considered building your own Android from the source?

You can use a virtual PC to build this from if you don't own a Linux machine. I use Ubuntu 14.04 running in a virtual PC on my main PC and followed the setup instructions found online. Takes a few hours to build it first time but once the first complete build is done, subsequent part builds are fast. Just remember to setup the cache option.

You can use a shared folder to move files from and to the VM and main PC.

I am busy porting the T4 so that I have Landscape on the eDP HD702 LCD display. I also removed a lot of the stuff I don't need so you can trim it down.


PS. If only I could upload 200GB of data I could share the VM I use and save you the trouble if creating everything from scratch. :)
Hi Dave,

Thanks for the reply. I have not previously considered building my own image from scratch, seemed daunting but now i'm going to look into it.

BTW: have you encountered the same problem when you build your own image?

Joemeister wrote:
BTW: have you encountered the same problem when you build your own image?

I had been doing development and had it always on so never spotted it until I saw your post and then waited and saw it not doing to sleep.
Hi Joe,

I've got it working. It now drops from 12V 500mA to around 12V 50mA when in sleep.

The display dims down and then after about 2 seconds, goes to sleep.

I had to edit this setting in:

Code: Select all


Code: Select all

<!-- Keep screen on at all times by default -->
<bool bame="def_stay_on_while_plugged_in">true</bool>

Edit this to false and now it sleeps.

BUT, I think if you enable debug settings you can edit this in the setting for Stay awake by switching this off. That will save you having to do your own build but I recommend you doing this if you want to have some features removed/add.
Hi Dave,

Awesome, seems to work! :D

I tried changing the setting in debug mode and it seems functional, however have yet to do power measurements to verify lower amps.

Added info for future reference: a reboot of android seems to be required after changing this setting in developers options for it to work.

Thanks a million for looking in to and fixing the problem Dave! Kudos!

Greetings, Joe
Hi Joe,

I've only tested on a basic power supply with max 10mA resolution but I will put it on my DP832A soon to do more testing as that can do down to 0.1mA resolution.

So far I like the T4 for this intended project. The only issue I have just now is the lack of external power connector so I have to solder 2 wires onto the switch. The T3 Plus that I use in another data logger project has an external connection via the headers.

The good thing for me is that the T4 fits onto the back of the eDP HD702E display so makes for a simple installation. A short ribbon cable to my GPIO/I2C interface makes for a simple build too.

Out of curiosity, what are you using the T4 for? I've attached the logger I designed with the T3 Plus which is used to read the data from a pressure/temperature sensor installed in an oil or water well. It also controls the VSD and I have a small 0.75kW one for testing as shown in the attached images. The T4 will be used as a touch interface for an ROV Control System.


Hi Dave,

To satisfy your curiosity :D : I'm using the t4 for home automation control panels.(i'm using 23" IIyama panels connected via HDMI/USB).


Nice. I'd thought about using them for this myself but use the eDP display as it's cheap and good quality and bright.

I run my home automation from a Raspberry Pi3 with Node-red and Mosquitto MQTT server. I am thinking to switch to a Nano PC T3 with HDD for OS and storage as I have a few of the non PLUS version from earlier testing.

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