Thank you RC. I looked it up and they did at one time based on an announcement in a web page circa 2010.
I typically use a PVC adapter with AAs but it'd be nice to have 5000 mAh. And then, there's that copper adapter in my thumbnail picture. I've made some for 3x C size flashlights to use 21700s and 18650s.
Iām a little leery. First, a C cell that only has less than twice the capacity of an AA cell? Ouch.
And some of the reviews slam these cells pretty hard. āWork only a short timeā, āstopped chargingā, etc.
Wellp, canāt think of many doodads I have which need C cells, soā¦
None of my doodads that require C-cells are mission-critical, so I use NiMH AA batteries with homemade "AA to C adapters" fabricated from 5/8" ID x 7/8" OD Clear Tygon tubing, cut to a length shorter than the battery using a thin chef's knife with a little water on it for lubrication.
I had issues with C-adapters I previously purchased catching on the springs of devices that use a spring at each battery's negative contact. My homemade "AA to C adapters" are a sloppy fit, but still work if I shake the device and are easy to remove without catching on the spring once I slide the adapter so my fingers are able to grip the positive end of the AA-sized battery.
When I use my homemade "AA to C adapters" in a tubular style flashlight that uses more than one battery in the tube, I stick a portion of a toothpick between the AA battery and the Tygon tubing so the tubing does not slip off of the battery and use a longer adapter on each AA battery if I have alignment issues between the multiple batteries.
The eneloop C & D adapters only hold 1 AA inside them,
There are C & D adapters that hold 2 or 3 AA inside them, but they are not made by Eneloop.
That's what I was talking about.
I just cut some 3/4" PVC pipe to a little less than the length of 3x AAs (~140mm).
Cool, didnāt know about those, thank RC
Diameter of an AA battery is 14.5 mm (0.57").
Diameter of a C battery is 26.2 mm (1.03").
You would need a diameter of 2 x 14.5 = 29 mm (1.14") to accommodate two AA batterys.
Only one AA battery can easily fit into the space designed for a C battery.
Also, a C battery is 50 mm (1.97") long which is shorter than an AA battery which is 50.5 mm (1.99") long, so the adapter needs to be shorter than the AA battery.
Okay, you're right about the AA to C adapter.
Only one AA will fit.
But there are 2 AA to D and 3 AA to D adapters.
This is the one that I bought, but I got a white 4 pack that is not available right now:
And there goes my power, rained all day and then temperatures dropped rapidly, guess a power line iced up or a skidding car took out a pole, time for flashlight fun, just hope power is restored before I freeze my butt off 
Already went through one obulb and 1 headlamp, but being flashaholic I got plenty to spare
Here are 3AA to D adapters, a set of 4 for $6.90 at Amazon.
You donāt have to use 3 in it, you can use 1 or 2, or 3 AAs,
https://www.amazon.com/gp/product/B00OUM17AQ/ref=ox_sc_saved_title_4?smid=A2Y9R0VEAYJBWE&psc=1
Here are 4AAA to C adapters, a set of 4 for $6.90
One can use 1, 2, 3, or 4 AAAs per adapter.
https://www.amazon.com/DSLRKIT-Parallel-Battery-Adapter-Holder/dp/B00OUM1GTI/ref=pd_sbs_4/145-4521008-4369349?pd_rd_w=EgaA3&pf_rd_p=4b6b5072-e9bd-4f30-a3af-a1f5d52978ec&pf_rd_r=JQ8JBK96J74WSJ4187PG&pd_rd_r=1d9bdf56-1afb-4197-b2ab-c1efb67011ae&pd_rd_wg=mZQw4&pd_rd_i=B00OUM1GTI&psc=1
Coupla Christmases ago my block was blacked out for a day. Those big-ass powerbanks are a great backup if you need to recharge a light directly, or even use one/more of those little usb-lights.
My Zanflare on pure WW and maybe half-brightness lasted all night, and was just on its last gasp when daylight came.
Stuck my Wuben Ewhatever (E01? E03?) above the catbox, lowest setting, diffuser, stuck by tail-magnet to the light fixture above.
Anything else was just light-by-demand if Iād poke around the house, go to the can, go outside, etc.
But yeah, donāt underestimate those powerbanks. They can top-off a light thatās running low, vs swapping cells in the dark.
Mood lighting for a cat box? You are really bonkers!
Heck ā¦ā¦My dog has been hassling me for an Outback kayak ā¦ā¦ā¦ Im about ready to give in! 
(Furnished) Basement, nighttime, no windows, no electricityā¦ I donāt want them crapping on the floor if they canāt find the catbox.
Kinda like that song from The Clashā¦
They see in the Darkā- LOL
They can see in low-light, but not in complete darkness.
Rock the CatBox? 
Iāve installed 2 solar motion lights in the enclosed dog-run that our 2 small dogs visit via a doggie-door at night.
Helps them tiptoe thru the last droppings and tease the bobcats, puma, bears that frequent our property.
