Two level LED strip on different voltage with separate switches
simulate this circuit &ndash; Schematic created using CircuitLab

Figure 1. (a) A dual supply dual brightness configuration. (b) A single supply with diode droppers.

It's a bit difficult to understand your unconventional schematics but here are two suggestions. How you incorporate the motion sensor depends on its output switching.


The diodes will each drop the voltage by 0.7 V.
You will need diodes rated for the LED strip current (at the reduced voltage).
The diodes will waste energy as heat all day.


Take your pick.









simulate this circuit

Figure 2. Beware of shorting out earthed DC power-supplies. Note that PSU2 is short-circuited through the earth connections.