12V, High Current ATX Power Supply Mod, Part 3

I ran some tests using the 12V lead-acid battery I pulled out of my motorcycle for the winter, and I’m only able to charge at a disappointing 1.5 amps, at which point the power supply is down to 10.07V, just above the charger’s low voltage cut-off of 10V. So, I either did something wrong, or I missed something. I’m not sure what I’m going to do about it at this point. At least I can charge though, if just at a very slow rate.

12V, High Current ATX Power Supply Mod, Part 1

My hobby charger, like many of them, runs on 10-18V DC, which is rather handy, as it allows you to use crocodile clips to connect it to your 12V car battery when you’re out flying somewhere, which is the handiest power source around. But, when it comes to home charging, this means you need a high current DC power supply. These can be rather pricey…or are they?
IMG_20120927_052531_zps41238748, Uploaded from the Photobucket Android App
Hmm, what’s this? I like hackable parts.

Enter the PC power supply unit, or PSU for short. These can readily be found anywhere for free, just watch for someone throwing out a desktop computer. Being a geek, I tend to get a few old computers, and when I saw this 450W power supply I knew I’d have a use for it someday. Well, I had done this once before, for my dad and me when I was younger, and I knew it wasn’t a hard job. The label from the above picture says I can get 12V at 18A, which is pretty dang good. That’s 216W, and I only have a 200W charger at this time, so I should be able to use the charger to its maximum capacity, something I’ve only been able to do with a car battery as a power source until now.

I have to go, so I’ll just leave you a picture, but I have the power supply in working condition. I get somewhere in the neighborhood of 12V, which is cool with me, but I didn’t do extensive testing yet as that’s not a smart thing to do with the current state of the power supply. Nothing is protected against shorts right now, so even just checking the voltage had a potential hazard. Not to me so much, but mainly to the power supply, as one slip could short the output and render the power supply useless.
Photobucket
It’s not nearly as dangerous as it looks, just don’t touch the fat traces on the printed circuit board…

Still to go is a power switch, two power status indicator LEDs, and lots of liquid electrical tape slathered on all the cut wires and soldering joints. This, as well as the process used to convert an ATX power supply to something useful outside a computer, will be covered in part two.