I had some spare computer parts after upgrading my PC. I decided to make a laptop out of them. First I had to figure out how to power it with low voltage, which would be easy to get from a battery pack. I found a LR1106 PSU that needs 11.2-12.6V. Perfect! I hooked it up to 12V from a normal ATX power supply to test it out.
Later I got a dedicated 12V PSU for further testing:
Then I had to figure out how to get a laptop screen to work with a desktop motherboard. I bought a screen and a controller board from ebay. The screen didn't light up at all, and after banging my head against a wall, I figured out that the backlight wasn't connected. So I plugged it in and saw this:
So I bought another screen and hoped for the best.
I've also been experimenting with Gentoo Linux to try to reduce the power consumption, but it hasn't led to anything.
Now I had to make it run on batteries. I got some 18650 cells from old laptop batteries, bought a charger and borrowed capacity tester from a friend.
I bought a cheap spot welder and connected 16 of the largest capacity cells together to make a 4S4P pack.
Then I bought a BMS and connected it to the battery pack. I also connected a thermal fuse and glued it to the battery pack with a thermal glue. I'm not sure if it was necessary, but I guess extra safety can't hurt.
I bought a buck converter to convert 13-16.8V from the battery pack to 12V to power the computer. Then I run it on batteries for the first time:
Now it was the time to make an enclosure. First, I made a prototype out of cardboard to find out the right dimensions. I also found an old tablet case with a USB keyboard that was small enough for this project.
I also used two xiaomi vacuum robot battery cases for my battery.
Then I started working on a metal case. I found out that I could make it out of two ATX power supply cases. I used rivets for permanent connections and threaded rivets so I could open the case later. I also salvaged a screen frame from a broken laptop.
I also experimented with a dedicated GPU, but eventually gave up because it would make the laptop too large.
Then I connected everything together.
One thing that was missing was the power supply switchover (which would allow me to power the laptop from a 20V wall charger) and a built-in battery charger. For this whole time I was charging the battery using a bench power supply, which wasn't very convenient. I made a circuit using a LTC44122 IC for the power switchover and bought a CC CV buck converter for battery charging. I've adjusted its output voltage a bit lower than the maximum 16.8V so it wouldn't overcharge the cells. I also added legs to the case for better air intake.