I have installed my VIM3 to my car to serve as infotainment system. I have been playing with idea to add UPS (4S LiFePo4 and BMS board) to give power for VIM3 and display when car is turned off. My question is will VIM3 reboot when mechanical switching relay operates? I have noticed that there is slight delay turning off while interrupt on power delivery. But is that enough?
I believe you asking for how much time it will take to shut down ?
Stock Android 9 pie, has a shutdown delay, just shy of 8-10 seconds
It totally depends on how many services/apps are running in the background that needs to be stopped…
Not quite that. More I’m interested if VIM3 will notice relay switching between power supplies. So that switch from cars power system to dedicated battery pack. There would also be board doing regulated 12V and 5V power for VIM3 and display. Will VIM3 reboot when relay pulls and switches power input?
You will probably get some drop in supply and so may get brownouts or sometime reboots. Would either stick a diode in line with each supply and join the diode cathodes together (effectively OR’ing the power supplies) or use something like a ICL7673 chip if you want to get a bit more fancy
That seems like a way to test. So something like MBR20100CT to connect power inputs? Or follow route of ICL7673 which detects drop in main supply from car and starts to use battery pack. I am little rusty on basic electronics but getting back to it 
Yep they would probably do it - easiest it it works! Stick a decent size capacitor the vim3 side of the diodes as well to keep the supply nicely up and should be good I would say. Obvs the higher voltage supply would power it with a basic diode circuit like that, so battery backup would have to be lower voltage than the main supply to make sure the supply works properly
I am interested in your circuit, also have you considered any automated orderly shut down process?
I am planning to use a vim3 on my motorcycle system as a GPS and other onboard systems when I can get a few of the shortcomings worked out.
Orderly shutdown with delay is something I want to work in, OR better yet, some way to have it go into sleep mode automated as the VIM uses so incredibly little power in sleep mode.
I started sketching with two switching micro relays. Other switcing between BMS and car for input to VIM3. Other to switch between load and charge battery pack. I’m using 12V line from car stereo head unit (ANT power) to control relays. From this part power goes through 12V3A + 5V3A charger/power supply (https://www.minimani.fi/waltter-fast-car-charger-autolaturi-6a.html link to my local store). Battery management system (BMS) and battery cells are still to be decided. Also sketch of circuit is hand drawn and not useful (many corrections overlaying…) Soft off and possibly sleep mode are yet not thought through. Maybe using XPWR tabs on VIM3?
XPWR for a External power button,
yes, it is a viable option… but right now, long pressing the power button, only gives you Power off, reboot and screenshot options…
we might need to ask Terry if he could add sleep functionality to that menu…
I ordered Arduino clone to start testing it as controller for power system. Or use it to give control signal to relays. As I understand there would be almost unlimited possibilities for delays and signal lenghts. Hope that standby could be added as option under XPWR.
Short press for sleep on button, remote or XPWR pads.
whoops, sry forgot that one…
I am loosing my marbles more than usual
Please forgive my Lapse of memory 
That is good info that short press on power button puts VIM3 to sleep. I have been emptying my wallet on Aliexpress today.
Also going to visit local shop for more 12V micro relays and diodes.
Generally using a silicon solution for low power switching is more reliable an faster right ? 
Silicon solution for control and delays. Mechanical relays for power lines 
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Yes, checked on XPWR pads function when tschultz was planning his truck dashboard project.
I hope your wallet survives the event. 
Wallet is taking deep breaths 
Now time to wait deliveries. Thinking about ordering third VIM3pro for testing purposes. One is installed inside my cars dash, second is waiting in chinese customs with USB port issues to be checked by Khadas team. I’m not feeling like pulling the one installed in car for testing.
“Silicon solution for control and delays. Mechanical relays for power lines”
There are solid state solutions that can handle the power of these units very easily.
https://www.amazon.ca/Bestol-Channel-Solid-State-Trigger/dp/B07F12MXR1
https://mausberry-circuits.myshopify.com/collections/car-power-supply-switches
Mausberry have been making these for years.
Those Mausberry board look nice but are for RaspberryPi and Linux. Also they shut down Rpi when ignition switches off. I’m making UPS to keep VIM3 and Android up when I stop and cycle ignition off and back on again to shut down engine. So VIM3 and probably also dashcam up with UPS.