12/24 volt system

[m16ty]

My RD822sx starts on 24v but everything else is 12v. It doesn't have the common series/parallel switch though.

The batteries are wired 24v but it has a 12v tap off the second battery. Both the 12v and 24v power wire runs to the alternator and there is a box on the back of the alternator that charges the batteries at 24v and sends 12v where it needs to go. I was just wondering if anybody has seen this setup before?

When I got the truck, somebody had wired everything up 24v. It blew the regulator in the alternator, most of the light bulbs, and the in-dash solenoid before I figured out what was going on. Luckily, everything else electrical survived. I finally figured something was going on when I was doing a light check and one by one they started going out. There was a battery wiring diagram on the box on the back of the alternator so I knew how the wire the batteries correctly.

When i took the alternator to the rebuild shop, he was able to fix the burnt regulator but said he didn't know anything about the box on the back. He did say the alternator puts out 24v but somehow that box also has 12v coming out of it.

I'll try to get some pics of the box.

[41chevy]

It a Step Down Converter / Transformer from 24 Volt to 12 Volt. Some trucks, most Military trucks and many Boats over 40 feet run them. for 24 volt start and 12 volt accessories in the cabin. West Marine, NAPA should have them if you need a replacement. Being a step down transformer it takes a lot to burn it out. Paul