PAT prefix. Don't have the entire serial with me at the moment. Had to do motor mounts on it last week and fount the battery stone dead. Not just low but flat. Jumped it to get the job done and then went on my way. The next day they called to say the battery was dead again. So I went back to check it out. Looks like it has had recent issues with the charging system because the battery was only a couple of months old. And someone went through a lot of effort to put a wrong battery in it. Like you have to remove the alternator and bracket to change the battery. I checked to see how the alternator was charging (as I did the first time when I had to jump it) and 14.3 volts. So, I got a right battery and installed it. Checked charging again with the same result, but the battery light is still on. Went to high idle and found that it was overcharging when idled up. Near 18 volts. Knowing cat skid steers and all of the UFO problems that happen with wire loom damage I lifted the cab to check that and found nothing. I am suspecting that the alternator has a bad diode. But, I would welcome some other thoughts and maybe a wire diagram, before I go back. I thought I had a diagram for it but I am only finding 226 and 248 in my library.
Don't need a full S/N. All PAT use the same schematic. Check your messages.
Certainly sounds like a bad diode in the alternator.