D6 9U Charging System

I just had someone pose me a question at lunch I couldn't answer. The starting system on my D6 9U 23xxxx is 24V, but does that necessarily make the charging system 24V? He seemed to recall some tractors having a 24V starter but the charging system was 6V. He thinks he worked on some tractors of this configuration which had four 6V batteries and charged each battery as a 6V. I had never heard of something like this, but it raised an interesting question. As I haven't spent much time studying the electrical system on the D6 it would seem possible to have a 24V starter and then charge each of the batteries as 12V, or even 6V if they were connected in series. I have just picked up my two new 12V natteries for the D6, I guess I just want to make sure I don't mess something up with the batteries or charging system. I surmise that since there are currently three 8V batteries in it that the charging system would be a 24V system. Also has made me realize the impoertance of getting my manuals ordered to improve my knowledge. Thanks.

Bryan

It could be done but a 12/24 volt system with a series parralell switch is more common. Used mostly on trucks to have 24 volt for starting and all other components standard 12 volt.
Later Bob

I don't think CAT ever did a series/parallel system. They just used a 24 volt charging system when they went to 24 volt starters. It's possible someone tried to rig up some kind of system to use the original 6 volt generator when they converted from pony to 24 volt direct electric start. The original installation would have had four 6 volt batteries in series. Someone must have gotten a deal on the three 8's!😆
I believe the regulator on your 9U will have an A1 and an A2 terminal. The A2 is shown on the end of the regulator and is grounded. There is also an A2 terminal on the generator which is connected to the A2/grounded regulator terminal. If you don't have either of the A2 terminals on the regulator or generator, try just grounding whichever is missing the A2.

The later 24 volt systems did away with the A2 and just have a ground, so later components may not have A2.

Your system should be 24 volt negative ground.

Before starting the engine, you need to polarize the generator. CAT manual recommends installing the batteries and connecting all wiring. Then close the battery disconnect before disconnecting the Field wire at the regulator and touching it to the BAT terminal for a second. Replace the Field wire on the correct terminal. Make sign of the cross.............Start the engine.😆

Found that our grader has had the ground wire and the field wire swapped at the generator for a year or two now. It finally quit charging because of the damaged regulator cutout (49 volts open circuit!) and the guy running it just began jumping it off and didn't say anything to anyone about it. He did notice that the batteries were dry and refilled them, so I guess that is something at least.

I got involved and noticed the swapped wires once I started looking for the reason behind the 49 volts. Amazingly everything but the cutout still works, so I'm going to install a pair of diodes to take the place of the cutout and see how that works.