Saving power

tve · 2019-03-10T21:21:49.428Z

I’m installing a GL-X750 (Spitz) in an RV where it runs from batteries (and solar) most of the time and I’m wondering how to reduce power consumption to the minimum. Does anyone have experience with that or suggestions?

I did some tests:

system idle with 2.4Ghz Wifi running in STA+AP mode ~1.8W-1.9W (~150-160mA@12V)
add 5.2Ghz AP brings it up to ~180mA @12V
add cellular w/EP06 goes to ~190-200mA @12V

I’m wondering whether under-clocking could help, but I doubt it. Any other tricks to reduce power consumption?
Is there a way to put the system into a timed-sleep? I suspect not and would have to implement that by cutting power from the outside…

kyson-lok · 2019-03-11T03:20:11.841Z

It is a router, not sensor, so it can’t be into sleep state.

If you want to save power, you can turn off both of 2.4GHz and 5GHz, and don’t attach any peripheral, such as modem or USB.

tve · 2019-03-11T15:48:04.951Z

kyson-lok:

It is a router, not sensor, so it can’t be into sleep state.

Sure… but it may be appropriate for it to sleep from midnight to 6am, for example.

jolouis · 2019-03-11T19:54:43.241Z

OK so you kind of answered your own question. The key reading you missed is what’s the power consumption with 2.4Ghz wifi off also?
If you wanted to sleep from midnight to 6am, you could easily use cron to run a script that would turn all Wifi and EP06 off at midnight, and power them back on at say 6am. Keep in mind during those times that obviously anything powered down isn’t going to be usable of course…

I’m not sure trying to tweak the clock would have any impact as these days most embeded SOCs keep their power consumption to a minimum and ramp up when you put load on them. So as long as you were not doing anything power draw should be at its minimum with the things like Wifi powered off.

What is the underling purpose of having it in the RV? i.e. if it’s to use only while you’re there then why not just unplug it or wire up a power switch to it when you’re not there?

tve · 2019-03-11T23:33:35.950Z

jolouis:

OK so you kind of answered your own question. The key reading you missed is what’s the power consumption with 2.4Ghz wifi off also?

Looks like the answer is 130mA.

jolouis:

I’m not sure trying to tweak the clock would have any impact as these days most embeded SOCs keep their power consumption to a minimum and ramp up when you put load on them. So as long as you were not doing anything power draw should be at its minimum with the things like Wifi powered off.

Yes & no. My browsing so far hasn’t been conclusive. I’m not convinced that OpenWrt includes dynamic frequency scaling. Or if it can, I’m not convinced it’s there for the QCA9533. I’m not finding anything that suggests freq scaling in /sys. I was hoping that someone who knows could respond to my post.

jolouis:

What is the underling purpose of having it in the RV? i.e. if it’s to use only while you’re there then why not just unplug it or wire up a power switch to it when you’re not there?

I hooked up a GPS antenna to the EP06 and can now use the GL-X750 as a tracker as well. So I’d like it to be “in service” all the time (in-service != everything powered on). I also don’t like devices that I have to remember to turn off, 'cause I’m bound to forget…

Overall, I’m also trying to understand the range of possibilities. I will be attaching an arduino-like embedded controller to the uart port (or ethernet) and use the GL-X750 as a bridge to report stats such as RV battery condition to a server of mine.

jolouis · 2019-03-13T13:04:33.908Z

If you are concerned about maximum power saving, then leaving the GPS and the cell radio active will be the biggest draw. There is nothing you can do about that really, unless you want to setup some kind of periodic wakeup/burst/disconnect kind of “idle” pattern to only enable things when in use. I’m not entirely sure doing that would give you much overall consumption saving unless your intervals were quite large, and if you’re talking about tracking/management/etc that might not make sense.

I think at this stage of the game you have things about as power-oriented as you can get. There are definitely more options for chopping down consumption, but then you’re also cutting out features that you want to use. So it’s a question from your side of choosing priorities.

David · 2019-03-14T02:19:44.730Z

Hello!
You can try to install wifischedule in Luci>software, you can schedule wifi on-off by hours and days and configure multiple plans, also there is the possibility to unload certain modules to save power.
Tried on a AR750S and AR750, don’t know in X750.
Bye