Those are a pretty neat light, and rechargeable from USB is also a neat feature. I hope nobody is using an inverter
just to power some 120Vac to 5vDC USB receptacle. The inverter turned on powering nothing will likely draw 2x as much as the USB recharged device requires to recharge.
Converting 12v battery voltage to 5v DC (USB voltage) is only about 80% efficient too.
Whether that loss of efficiency matters, depends on the particular recharging capacity of the user of course. If that 20% makes or breaks someones system well they likely need more recharging capacity anyway.
I am pretty firmly in the 12v LED camp for my interior lighting. My favorite lights are currently employing this type of bulb:
This bulb base is also known as a T10 wedge bulb base, and some incandescent bulbs which use this base have numbers like 168, 194, 914, and 921 to identify them.
The LEDs shown above are quite bright and fit in the salt and pepper shaker style of lamps my conversion van came with, but heat has proven to be their demise.
i have bought many of these T10 receptacles, but the cheapest of them still smell like stinky harbor freight rubber 1 year later:
https://www.amazon.com/uxcell-Wedge-Light-Instrument-Socket/dp/B00W8W5MR4/ref=sr_1_fkmr0_1?s=automotive&ie=UTF8&qid=1517169341&sr=1-1-fkmr0&keywords=T10++wedge+base+receptacles
My actual favorite light is a 99 cent store gooseneck light originally designed to run off 2 AA batteries. I ran some thicker wire up te gooseneck stem, installed 3 T10 receptacles in the hood, and put a better push button switch and an LED dimmer in the base of the light.
With three of those bulbs it is extremely bright, and i can aim it anywhere and not have the light source visible to my eyes. At full brightness the three bulbs get too hot if left on high for over a minute, but it is likely over 1000 lumens.
For reference, a sealed halogen 6054 5x7 rectangular headlight bulb on a car low beam, from the 1980's, is about 1000 lumens, and required 55 watts of power. My homemade gooseneck light requires about 8.8 watts at highest brightness, and about 0.4 watts on the lowest. The bulbs claim 450 lumens each, but I suspect they are more like 350.
I have been using the guts from these PWM led Dimmers in side my light fixtures. the actual circuit boards take up a small fraction of the space inside that housing shown:
https://www.amazon.com/BestLED-Dimming-Controller-Lights-Ribbon/dp/B00H8KTXNU/ref=sr_1_4?ie=UTF8&qid=1517169458&sr=8-4&keywords=PWM+led+dimmer
This post is not intended as a 'you are doing it wrong!' I only wanted to share what I have done to meet my interior lighting desires which are basically: white without obvious blue, very bright, and dimmable, and Aimable.
The T10 bulbs are easily replaced, fairly inexpensive, and when the latest and greatest LED chipset comes out, I can get perhaps more light for less wattage and heat generated with a 3 second bulb swap.
My initial T10 wedge base LEDs from 10+ years ago are absolutely pitiful in terms of light output, light color, and wattage consumed for that light, so i feel my existing system allows for easy upgrades when the products come to market. I have recently ordered more of the bulbs pictured above, as they do tend to burn out if left on highest brighness setting for a long period of time, and battery charging voltages exacerbate this, But 50 cents a bulb is acceptable, and their light color and output is favorable to me.
I am not sure these LED bulbs are driven as hard as the 'CUTEQUEEN' versions I originally purchased 10 of, then 10 more, but the design is the same.
https://www.amazon.com/Ecosin-Fashion-Canbus-White-Car/dp/B01M0ZZECH/ref=sr_1_133?s=automotive&ie=UTF8&qid=1510284686&sr=1-133&keywords=5730+led+bulb+t10