lithium lights that also take alkalines/nimh

I like powerful lights that run on lithuim cells but if in a pinch and your away from a charger or source of primaries, are there any 18650/2xcr123a lights that will run off an AA size cell in an adaptor? It wouldn't have to run as before just give out 100 lumens or so in an emergency?

If there are no lights like this would it be a good selling point and a viable option electronically to include a battery adaptor to run off AA cells in a pinch?

Steve.

I know there are a couple 1xCR123a models that will run off a single AA with an adaptor. Are you specifically looking for 18650/2xCR123a?

Foursevens Quarks are Lego-able for different battery tubes. However, you have to choose between the low (0.9-4.2V) and high voltage (3-9V) heads. The LV head is good for anything 1xLi-ion and 1or2xAA, but you have to go to the HV head if you want more lumens, or to run 2x123 and 1or2xLi-ion. The HV head will run 2xAA in a limp mode where only the lower modes will work - how many of them just depends upon voltage.

4/7s also does not sell 18650 tubes any longer, although you might find one used, but the 17670 cell works.

If you search in the threads about Malkoff M31 and M61, you will find things that you can do with various hosts and battery configurations for this purpose.
Most specifically, using an M61 in a 3-cell host like a 9P will allow you to use 2 x 17500, 3 x cr123 as normal loads, and 2 x 14500 or 2 x AA as alternatives for emergencies. It helps to have some paper or other wrapping around the thinner 14mm cells to stop rattle. The 2AA load will have much reduced output, but will work.
If you have a 18mm bored Surefire 9p host, you can also use 2 x 18500 in it too.
You can do similar things with 3-cell Elzetta hosts.

Also, if you have some cr123 dummy cells, you can use 2 cr123 or even a single cr123, by using the dummy cells to take up the rest of the room in the tube.

The Jetbeam RRT-0 will take an AA battery with an extender.

The Zebralight SC80 has an internal adapter for CR123 or AA batteries. The Sunwayman V11R and V10R have small extender accessories for AA batteries.

The reverse is also around. There are man 1 AA lights that can also take the 14500 Li-ion battery for an extra boost in output.