Two 9V in Parallel Power Supply

[Paul_KD7HB]

@SteveMann

Trucks and trailers do often put lead-acid batteries in parallel, but lead-acid batteries are more tolerant of a small imbalance.

Two in my truck and two in my 5th wheel trailer. You always get a voltage equal to the lowest voltage of the two batteries, but twice the current of one. The also charge to the lowest voltage.
Paul