A few considerations.
D cell battery = 1.5 volts
3D cell batteries= either 1.5 volts at 3x capacity OR 4.5 volts at ~3000mAh capacity
if, IF it is 4.5 volts, one could power this lantern Via a USB plug which are 5 volts DC. There are 4 wires in a USB cable. Red+ black-. Disregard the 2 other wires. Easy peazy.
The extra 0.5 volts is not going to hurt anything. Alkaline batteries are fully charged at ~1.65volts. 1.65 x3 =4.95V
One could use rechargeable NiMH batteries. I personally dislike the disposable alkaline battery mindset. I think feel batteries winding up in a landfill is a crime against nature.
If one has some wiring skills, one might be able to recharge NiMH batteries Via a USB plug whilst the Nimh batteries are inside the lantern.
But a dedicated charger is probably better. NIMH batteries are generally very tolerant of owner negligence concerning charging.
http://www.amazon.com/gp/product/B0..._m=ATVPDKIKX0DER&pf_rd_r=1F21H6855TFKD4GXSJGA
http://www.amazon.com/Universal-Cha...1-11&keywords=nimh+charger+d+cell+car+adapter
Now some more personal opinion.
I dislike lantern style lights. I find they give me a headache when the bright light source is able to meet my eyes. Over the holidaze, I was at a home where a single lantern of this style was placed on a table at the lowest setting, I still wound up stacking things in front of me to block the light for my eyes. I find lantern style lights to be obnoxious in use, and was always the guy secretly Whohoo happy at camp when a coleman lamp got knocked over and the mantles shredded.
So, would not consider this to be the perfectly simple light solution for a van dweller minimalist?
No.
Will it work? Sure, but is it bright enough to use as a task light? Maybe, depends on the task.
Do I have any other proposals? Of course, but they are not for everybody, just as I do not like lantern light.
Firstly, every single 12 volt car bulb out there has a drop in replacement LED equivalent, that at most, will use 1/4 the electricity of the incandescent bulb it will replace, and 1/10th for the same amount of light can be expected too, from the better LED bulbs.
festoon, T10 wedge base, and BA 15s are some common style 12v bulbs for interior lighting
http://www.amazon.com/s/ref=nb_sb_n...:228013,n:322525011,n:2314207011,k:ba+15s+led
http://www.amazon.com/s/ref=nb_sb_n...=n:228013,n:322525011,n:2314207011,k:t+10+led
http://www.amazon.com/s/ref=nb_sb_n...228013,n:322525011,n:2314207011,k:festoon+led
These LEDS can vary greatly in light color and output. Some can be dazzlingly bright, some might be surprisingly dim. Some can be very blue and harsh. They do sell warm white versions which are closer to the color of incandescent lighting. I prefer the whitest of interior lights without any blue. I dislike blue light.
I'd recommend getting a few extremely bright LEDs for a few key stock interior light housings. and having a few dimmer ones too. Pop off the light cover and have a look.
Please do not install LED bulbs in your external signal lights that were designed for incandescent bulbs. In most cases they are unsafe and illegal. They will not fill out the lens correctly, nor have the proper brightness difference between running and brake light, if a dual filament bulb like an 1157.
Now, even for outdoor tent style camping, traditional home of the lantern light, I find the lantern light to be inadequate. Headlamps rule here as light is always where you are looking, can be easily turned off when not needed, and can easily be transferred to van dweller duties.
I use a Nitecore HC50 headlamp:
http://www.amazon.com/NiteCore-XM-L2-Lumens-Headlamp-Black/dp/B00GNJM3AM
These use a single Li-ion 18650 cell, or 2 cr123 lithium disposable cells.( DO not MIx old and new!) 565 lumens is fairly extreme, but there are 5 brightness settings as well as strobes and SOS, and red LEDs too.
I use a Nitecore I4 v2 charger, which can operate from 12vDC (12vdc wiring plug not included) and which will also charge most every LI-ion size, as well as AA, and AAA niMh batteries
http://www.amazon.com/NiteCore-Inte...F8&qid=1422760163&sr=1-1&keywords=nitecore+i4
While I have some top quality panasonic NCR 18650B cells, bot protected and not, I recently harvested 9 18650 cells from an old laptop battery. 8 of the cells have a lot of capacity left and used regularly.
These Li ion cells are pretty safe, especially when not used in parallel or series with other cells. Cells are available with protection circuitry to prevent overcharging and overdischarging. I do not think unprotected LI-ion cells are safe around children or those who will run them down dead. Cells pulled from laptop batteries are not individually protected. Many XXXX-fire 18650 cells sold on Amazon for cheap are recycled laptop batteries, and claim to be new and to contain protection circuits. They LIE!. Avoid Lithium ion battery cells like trust fire and surefire, and certainly do not use them in series or parallel in devices that use multiple cells.
Anyway, this is a good headlamp, and a good charger. There are better available, and worse. These are what I have experience with and can recommend.
I tend to use this headlamp for every task I do which requires lots of light. It usually lives in my tool belt, and simply allows me superior acuity of details on projects.
A headlamp in Van dwelling is simply awesome, especially for interior tasks. When I fly to visit family x country, I bring this light and use the 1 lumen lowest setting as a reading light, and usually for other tasks when people ask me if I can fix this or that.
While I do employ a few original or slightly modified 12v incandescent housings with LED bulbs inside them for the interior of my Van, I've had to make my best lights.
My preference is a very bright white light, with a shroud to block the light source from my eyes, and allowing it to be aimable. I modified a 99 cent store LED gooseneck light with a T20 Cree LED bulb which was designed to be a reverse light for some vehicles:
Here is one of them illuminating one under construction:
I either aim these downward at my stove or table, or upward at the white ceiling for ambient light. One of them I have on a long cord with a ciggy plug and can move it where needed anywhere within 25 feet of my Van, and it often winds up in somebody's tent or on the communal camp table, when camping with others in a campground. Well, they are camping, I am simply parking.
My interiors incandescent housings take T10 wedge base LEDS. These are the best LED's I've found for these particular lamps:
http://www.amazon.com/Philips-12964...8&qid=1422761166&sr=1-2&keywords=phillips+t10
The light exits only the very end of the bulb. It is not the brightest LED I have, but it is the warmest color, and the most efficient. Lots of light for extremely little amp draw. Phillips is also the only LED bulb maker which had DOT compliant bulbs for exterior signal fixtures, but they are only compliant in some vehicles. Most would be better off just staying with incandescent bulbs in exterior signals. The few benefits of LED in exterior fixtures do not outweigh the risks of having the signal light not perform as designed.
I have about 2 dozen LED lights in the t10 base that I do not use and will likely not ever use again. If someone
really is in need of a t10 LED and has a t10 wedge base receptacle to install them in, I can mail, or hand, some of them off.
That is a standard t10 194 incandescent bulb on the right, it draws 0.4 amps. The brightest LED to the left of it is under 0.08amps