Will disconnecting the 12V cable mess things up?

[US6x4]

I've got (2) 8D batteries wired together for 24V and I'm wondering if disconnecting only the 12V terminal will hurt anything or will it cause some sort of uneven draw? I'm, uh, asking for a friend...

The +24V terminal is turning blue (corroding) on the exposed wires where the sheath has pulled back a bit so it's making me a little suspicious.

 

[98G]

Sample size of multiple trucks over multiple years and tens of thousands of miles says no problem.

 

[US6x4]

Sample size of multiple trucks over multiple years and tens of thousands of miles says no problem.

Well that's saying something. Thanks for the input!