Nowhere can I find the current draw of a LED Flashlight. The manufacturer deliberately leaves this vital information out in their sales brochure.
Not only that, the construction is such that standard meter probes cannot be used to make a measurement. Inserting a spade fork in the battery pack shows a current draw of .140 A (140ma) at 20V. For a 1.5AH battery pack, this works out to 10 hours light time. It looks like the battery powered tools are sold without batteries because the Lithium battery pack cost 2-3 times what the tool is worth. Charge times are as yet unknown and are rarely published.
My guess is that the battery life decreases slightly after every charge...by how much is, again unknown. This confirms my belief that battery technology has not kept pace with other technological developments...More to follow.

Cheers, DPW [ Everything has limitations, and I hate limitations.]

 

The Technology has "kept-pace", that's not a problem,
the trick is to make the device so cheap that everyone can afford 3 or 4 of them,
and simply throw them away when they stop working.

Just a sad fact of Life.

On the other hand,
you can certainly make a very trick DIY Flash-Light,
complete with a custom Charger,
for only around ~$60.oo !!!!!

I really can't complain about the performance of all my ~$3.oo Flash-Lights.
.
.
.
.
.
.

 

From a manufacturing standpoint - - - most of their customers would not understand what AmpHours or WattHours means. While you and I and those who are far more regular here than me - that information is useful. But to most of my friends that information is meaningless.

As for "Standard Construction" - - - they want to make it as easy to manufacture as possible. Whether the bulk of their potential customers will want to poke at it with a meter - - - monetary concerns take precedence. That's why I often have to make things I can't just buy. I'm probably one of maybe 10 people world wide who want something my way, and there's no money in manufacturing that odd little washer with the bumps on the side - or a bolt with a hex head that measures 2/3". They tend to stick with more standard dimensions.

You're just going to have to figure a way to achieve your goal(s). Perhaps we can help - but not everybody sees the world the way I do. Nor do they see the world the way YOU do.