Running 12v accessories from 24v D6D

before there were converter boxes................

split the 12 volt loads evenly between the two batteries (can be hard to do exactly

or

Put 2 identical 12 volt loads like 2 lights etc in series circuit and apply 24 volts to the circuit

Add a resister ahead of the load to drop the 24 volts to 12.

Or just get a converter box.

You could get a Series Parallel Switch from an old Mack truck to do the job for
you. Back in the 50's/60's all the B and H model Macks had four 6 volt batties. Two on each side were wired for 12V and then went to the series parallel switch to create 24V when starting. Everything on the truck was 12V except the starter. The generator was 12V, lights, everything 12V except the starter. When you pushed the starter button, a spring loaded washer (selenoid) moved up to make contact with 2 points to give you 24V for starting. When you released the starter button the washer went back to 2 contacts to give you 12V for operations.

Here is the wiring diagram that goes with the Series Parallel Switch that "old 3T" mentions.
I don't know how well the charging system worked with this arrangement but most likely the loads had to be balanced for success.

I think I misunderstood the question.

I have run lights and fans off a single 12V battery in a two battery 24V system. Radios and computers....I don't know if that would be wise or not.

I have run some light load 12v acessories off of one 12v battery on my 24v system on my 941b. Have had no problem with the batterys charging in my 6 years with them.

OM,
From your wiring diagram, I'd think the 12V load should be connected to the right hand battery as it has a direct charging path from the alternator. The left hand battery's charge path would be (I think). with the SER/PAR SW not activated, through the switch #1 to#6 (grounds battery negative) and #2 to #5 (connects both battery's positive together). I don't have a clue how the Ammeter can measure any charging current (though it could be the ground path for the left battery).

Daron

Hmmmm,
I was thinking the 12v loads would be on battery B and there would be a connection at 3/5 with loads between ammeter and ground. Kind of hard to tell without the internal circuitry of the switch.

Here is what the actual switch looks like.