My idea for next gen LED lights..

..I like using AA rechargeable batteries, as they're easily available and most of us use them for other things around the home. However, the thing I like about my Fenix P1D (wich uses a CR123a) is it is quite stubby, and somehow feels 'right' to carry around.

the AA lights always tend to be slightly too long because of the light engine which adds maybe, what, 2cm?

So, I'm thinking when is someone going to create a light engine that is cylindrical, and can be 'wrapped' around the inside of the battery tube? :thinking:

Hopefully it would be possible (eventually) to have an AA light that is barely thicker widthwise than a CR123 light, but shorter than currently available AA lights.

Right, where's the patent office...

Great idea.

I was thinking something similar..
..there's usually dead space around the reflector.. space that could be used to house pcb/driver, switch.. and make the flashlight shorter.

Interesting idea.

But...
The 1AA Zebralight H50 is shorter than a Fenix P2DCE by quite a bit.

There are 4 things that contribute to flashlight length:

1) The battery. If we want to stick with AA, there is nothing we can do about that.

2) The switch. Clickies take up room. Until I got my L0P SE, I carried my Civictor in my pocket rather than my L1P. Difference about 1/4" or 6mm.

3) The reflector or optic. Unless you want to give up throw there is not much you can do.

4) The light engine. This consists of:
4a) The LED and heatsink. Not much we can do there.
4b) The circuit board. While a flexible circuit can be made to wrap around a battery it is probably not worth the effort. The chips do not bend.
4c) The lumpiest item on the circuit board on powerful 1AA torches is the reactor. As this is just a coil it is probably the best item to go between the battery and tube. We might save 3mm.
4d) Power contacts to the electronics. Once the reactor is removed from the circuit board this could probably be just be the back of the circuit board.

I have found from carrying the UK 2AAA eLED that a flatpack sits comfortably in a pocket. So an alternative would be to build a double barreled light with the battery in one barrel and everything else in the other.
Now where did you say the patent office was?

The circuit itself doesn't add that much length to a light, if you were to remove a circuit altogether it is only going to realistically shorten the light by about 4-6mm. I have thought about the idea of packing the components of a circuit around the backside of a reflector, but with anything less than a large reflector it would be quite a bit of added effort and design for saving only a few mm's in length.

I have thought about things like this many times as I have thought up ideas for designing lights if I was ever to build one, and I like lights to be as compact as possible within reasonable limits for a given battery size. The biggest waste of size in many lights is the space consumed by the switch - I've seen tailcap switches that could easily be 1cm shorter than they are. And then look at side switches, look at how ridiculously oversized a light like a 2D maglite is. I have AA lights like the Elly that, while decent lights, are much bulkier than necessary for a AA light. I have modified a light with a reflector the same size as the Elly that fits an 18650, uses a rear switch, and it's identical in length to the Elly. So for basically the same sized light, they could have built a light that could hold a battery with 3 times the capacity. So I do share your desire in having lights made more compact, but I don't think that trying to change how the circuit is put in a light is the best or easiest approach.

IMHO for small EDC lights, I believe the the space should be solidly packed with conductive material (copper or aluminum) to aid in heatsinking. Only in large lights like Maglites etc. is the space around the reflector significant enough to be worth installing components there. Also, small lights need all the help they can get for heatsinking, especially ones that dissipate 3 watts or more.

The switch is probably the best place to trim space usage down. The use of tiny signal-level toggle switch could both cut the size of the switch assembly down to nearly nothing, AND result in greater reliability and less cost than a good mechanical switch (the keys on your keyboard, which are basically variable capacitors, effectively never wear out). The actual switching of the light off and on would be handled by the PCB rather than manual opening and closing of the circuit.

Now, what I would like to see are some 18650/18500 lights that are as compact as possible (barely larger than the cells themselves -- similar to the way AA and AAA cells are designed). For example, an 18500 is the same length as a AA cell, I would love to see a light that is the same length as a AA light like the L1D-CE, but only 4mm wider diameter, packing 2.5x the capacity.

The next thing I'd like to see is a light that could host a hotwire bulb like the Philips 5761, or ROP-Hi on 2C-Cells, that was small and pocketable like the Lowes Task Force light (not bulky like a maglite). Pulling a nearly 1000 lumen light out of my pocket would be quite a novelty.

I was worried the Fenix L1Tv2 was going to be too long but it seems to be a perfect fit for me. You can get caught up with numbers comparing lights, but actually handling them is the best way to decide. One size does not fit all.