Power on/off on ignition state, car install

Hello community, after “failed” to build a car pc using a normal pc with android OS I decided to do some research regarding khadas.

So, I would like to build a car pc using khadas but I have a problem regarding the power on and off control. I didn’t buy it yet so that’s why I am here.

Before any possible solution I want to mention that my programming skills are near to 0. So I think I would need a hardware solution and I was thinking at 2 options.

First one, khadas has that power button but I don’t know how it works on android. When it’s pressed the pc goes in sleep mode or it’s powering off completely? If it goes in sleep mode I think the best solution for me is to build a circuit board that sends a pulse every time the ignition is on or off, something that simulates the press of the power button. Now, my question is, what is the power consumption in sleep mode?

If the above solution is not possible, I was thinking about using 2 power supplies, one for permanent powering and the other one on ignition. Now the question is, does the pc make the difference between two different power supplies? I mean, I can use vin pins for permanent and the ignition one through an usb port, if khadas make the difference between them( ac charging and usb charging for example) I think I can use an app like Tasker to do some tasks when the second power supply is connected. I’m not so sure if this would work, just an ideea.

So, please tell me how the power button works and if somebody did this before. I’ve read the other topic about this and Dave’s project but I don’t know how that power supply works.


why turn it off? it uses only 0.5 amp/hour
you can use pass through power bank that can work as ups
when car is on the power bank charges itself and supply the vim at the same time
when turn off the car the vim will still working by power supplied from the power bank until your next day
20000 ma will keep the pi on for 16-18 hours
and you can power the screen directly to the ignition power supply so turn of with car switch

hope that will help

1 Like

Hello, VIMs power on when power is applied, regardless of the port supplying power.

Physical power button running Android…
Quick press=sleep/wake. Current draw during sleep seems negligible.
Long press=Power shutdown menu.

VIMs can be fitted with a real time clock(RTC) battery.

See docs.khadas.com for schematics and other information.

I have no experience with VIMs used in car installs.

I don’t need to power it off completely, I would prefer a sleep mode. It is a possible solution but not the perfect one, that power bank, if it really has 20000ma that means 20 amps, with a 2amps charger will need 10 hours to be fully charged from 0. Yes, it won’t be at 0% next day morning but even with 50% still get a huge charging time. And another problem is the battery itself, I don’t like the idea having a battery in the dashboard.

RDFTKV thanks, that’s the answer I was waiting for.

Less than 20mA at sleep mode for both VIMs.

And it’s uA level in power off status.

What do you mean this? For both VIMs, the devices will work if any one of these is supplied.


Perfect, 20ma sounds very good.

Regarding the difference between two power supplies, a phone or a tablet, when is charging, if you go to power/battery menu it sais what kind of charger you’re using, either usb either ac. Of course, khadas doesn’t have a battery so is not charging, but I’m thinking it has some sort of power management so that’s why I asked. But I don’t care about this anymore as the power button works how I wanted. Thanks for the info.

1 Like