under hood lights! I need idea guys.

Look at my first pic, you will see a small blue led on the fuse box. thats my rocker switch for the lights.
I do like the idea of using a 9volt battery to run the lights for a disconnected battery situation..

Given these lights operate at 12-24 volts. Wire up two 9 volts for 18 volts and use a diode to keep the primary battery separated from them.
If someone was to get real crafty and buy the battery holder. you could use 4 18650 battery's for 14.8 volts and allow the Alternator to charge them Via a
Battery Isolator.