Electronic – Supply power to mini-ITX from car battery

There are two components to powering a computer: The rectification from AC to DC, and the regulation from one DC voltage to another, like 3.3 or 5.5V.

The PICOPSU-160-XT is a tiny form-factor device that regulates 12V DC down to the +3.3, +5.5, -12V, and other voltages required by the ATX Power Supply Specification. It requires a 12V input from a male plug into a "Female, panel mount, 2.5*5.5*10 mm" jack according to Page 4 of the (brief) manual. This jack would presumably be attached to your computer case.

The easiest solution would be to buy four AC-to-DC desktop wall warts, like the kind used to charge laptop batteries. However, the biggest one on the store you used only delivered about 8.5A, which is just over half of the 16A maximum (13A continuous) that the PICOPSU supports. You would need to know how much current your computers will be drawing, but this may be OK.

Another alternative would be to purchase a desktop ATX power supply of sufficient amperage (600-1000W), and run ATX power supply cabling into your four computers. Similarly, four small PSUs could be used to the same effect. Visit newegg for a good selection of power supplies. We'd have to know more about your setup to determine whether this is a viable solution. - Would bulky, short cables going into your computers be OK? Would they be located within a few feet of each other? Would a (relatively) bulky ATX power supply fit into the case?

It's like the weakest point in the system.

For example on a car the tires may only be good up to 130 mph but the engine can go up to 140 mph. Or something like that, I'm not a car person.

Really it's being a bit cheap to only stock the 102W supply. If you want a decent 12V supply you should look at an ATX power supply. In fact the pico PSU could be replaced by one of these entirely. Only go for that brick if size is a problem. Even then, you can find a 150W ATX PSU in a small form factor nowadays anyway.

Additionally I would find it very difficult to believe that the pico PSU can provide 150W without cooking itself. Looking at it, the inductors are small surface mount types, probably not greater than 4-5 amps continuous. And I can't see a power transistor; if there is one, it would need some serious heatsinking. (Think about your computer power supply: 300-400W, about 2x as much as the pico PSU but with a large heatsink, plus it has a fan. Yes, one operates off 12V and one off mains, but the mains PSU's FET will actually have less current flowing through it and probably run cooler.) I would like to be wrong, but I can't see it.