Schematic for parallel/series battery switch..

[BennyFX]

Hi, I'm a newbie here...
I'm building a power supply that can switch between 12v and 24v, copying an existing design, that uses 2x 12v batteries and 2x integral chargers.

I made a schematic of the existing pack and I'm confused by the wiring. The wiring I imagined would use a dpdt switch both batteries from parallel to series.. this is something different and I'm not sure why it's done this way.. here is a photo...

It seems the batteries are wired in series, but in 12v position, the switch bipases one battery, and in 24v it is in series, but the neutrals are still linked...

Any help understanding this?

Thank you!

 

[Gryd3]

Try this :
Resting state... both batteries are Parallel.
Switched state, batteries are in Series.
The positive and negative outputs are separated and placed on either side of the relay.
You will need a double pole, double throw switch for this to work

 

[Harald Kapp]

I made a schematic of the existing pack

That schematic can't be right, as in the right scenario the left batery will be short circuited.
Gryd has given good advice.