Hi, I am designing and building my CarPC, based on an laptop with a broken screen.
I have chosen to go with a Carnetix 1900 PSU, instead of an inverter. I think its just cleaner, but I am still installing the inverter I bought. Anyways I was going to build my own Webmasters Laptop Auto Turn on Module, but upon reading the instructions for the Carnetix PSU. I realised I need a bit more to make it work. So far this I have come up with this diagram.
I don't think it's all that complicated, anyone could build this.
It senses the ACC/IGN circuit -- turns on the laptop from battery.
Laptop turns on the Carnetix psu through power to USB.
Carnetix will then power on my usb devices before windows has loaded.
When the ign/acc is turned off -- power is cut to the laptop battery, the software will shutdown the laptop. which will turn off the usb port -- which will turn off the carnetix psu. which will then turn off the usb devices. After windows has hibernated
This should cover any usb/software conflicts.
As per Webmasters design, I included the safety to prevent the power button from being pressed by accident, and the button to push the power manually if you want to.
I also put in a valet switch to completely disable the CarPC and the Carnetix PSU. And also a bypass switch keep the power on, or turn on the power without the key in. I put in an optional "status light" circuit to tell you if the bypass switch is on.
This is a WIP and I haven't actually finished this module yet. I am posting this to share my design with anyone interested, and to get some feedback on it. This design could easily be adapted to an inverter with the Carnetix-IGN wire going to a relay turning it on. I also plan on putting in a USB port with data wires from the laptop, and maybe power lines from the carnetix.