Ive got the same 12V usb all over my van too. I did however leave the rubber covers on.
The blue led in them is very bright at night and any blue light at night will give you bad sleep.
Blue wavelength light triggers the wake up time portion of human brains. Always avoid any source of blue light in sleeping areas such as, led's on TV, alarms clocks etc.
Ive also been wondering how much current does the voltmeter uses , bean meaning to measure that, thought of putting a push button with it to minimize power draws in my van.
Between
co2 monitors
carbon monoxide detectors
leds from the usb ports
built in voltmeter
wifi controlled lights (now on its own switch)
The draw adds up, when boondocking.
I have replaced all my interior bulbs with a mix warm white and daylight(6500k) led bulbs so I have gains there.
Btw the warm white leds feel very nice at night for a "cosy feeling"but I have each double fixture with warm white led bulb as the first one to come on then a 6500k led bulb as the both lights option for when I need more brightness.
Also right now i am only using 1 agm 24 battery which is small.
I am going to do possibly get a 31 agm battery in the spring and put in a dual battery selector. Unfortunately the battery layout does not allow me to have two 6V batteries due to height restrictions
Unless I mounted them somewhere underneath my van (awkward)