When a producent provides information about the runtime of a rechargeable flashlight it is obviously measured on a fresh battery and it should decrease over time. I would really like to know how quickly will the max runtime change. For example P7R Core with its Li-ion 21700 3.7V from the factory should run 90 hours at 15 lm. How many days of an avarage usage would it take to get down to 80 hours for example? Would Li-ion 14500 3.7V in a P5R Core behave any different? Can anyone estimate that or give me a source for an answer? Thank you in advance.
Battery life (what you are referring to) is a function of many things. Number of charge/discharge cycles, age, exposure to heat and cold to name a few. Quality of the battery is probably the most important. Some batteries are outright horrible.
Assuming the battery is good quality, you don’t abuse the light, and you charge it twice per week, the run time will probably be reduced by 10 percent in three years.
This by no means is linear. Meaning, don’t expect a 10 percent drop ever three year. The drop will be more and more as the battery ages.
Bottom line, I would not worry much about it. The battery should last in the 8-10 year range. Ballpark
This is usually based on theoretical calculation don't expect to reproduce it.
Remember that even two brand new cells from same manufacturer have a bit different capacity.
P.S.
In my opinion don't even consider buying any LedLenser light.
1. Their quality is not even close to justifying their price.
2. The worst technical support I have received from a flashlight manufacturer (including Chinese manufacturers)
LedLenser is not an enthusiasts light. Not to be compared to Convoy or Astrolux that are enthusiasts lights. They are meant for reliable home use. You will never see unprotected batteries used in LedLenser, you will never see 10 million Lumen rantings.
They target the Maglite user that wants something better.
Imho Ledlenser (LL) is aiming at the muggle-market.: one flashlight fits all.
So it has to be “flexible”=> zoomie with an easy UI.
Most of those end up in a kitchen drawer.
In NL a LL comes with a 7yr warranty, but I guess battery and/or “bulb” are excluded.
In NL LL is sold by DIY and outdoor shops (though not by the big retail chains).
Which means that for warranty issues you have to knock on the sellers door.
Never forget: the person you pay is the person who has to provide the warranty.
Never agree to his kind suggestion to bring you in direct contact with the manufacturer. Once the seller is out of the loop, he’s gone forever. Good luck getting Chinese support. BTW: LL contains lots of plastic parts so trying to repair one is real advanced modding.
As for the battery itself: what’s in it before LL had it custom rewrapped?
Is it a cell from a reputable manufacturer or the cheapest offer from a(ny) wholesaler.
I imply nothing, but does LL realy know they are reselling a good battery, or just hoping.
Some six years ago I bought a couple of Keeppower batteries from BG (I know……).
Today they are down to 10% - 77% of the number printed on the wrapping.
A year earlier I bought some Efest batteries from NKON: the worst of those is 97%.
Oh wow.
First of all, thank you very much for help and advice. I appreciate it a lot.
Second of all, you guys are giving me a tough nut to crack 
I have spent more than a week going through a bunch of manufacturers and their options and now when I thought I made a choice you are putting me back in doubt 
In my case I am buying a flashlight as a gift. Reliability is a priority. On top of that I want something that feels “premium” and actually has a good build quality. And the less Chinese a flashlight is the better. Since I couldn’t find anything serious that would be fully made in EU/NA, because everywhere I looked the production was done in China/HK, I decided to at least pick a company that have their HQ in Europe.
When it comes to Ledlenser, on top of checking all of the boxes listed above (at least as it seems like to me), I like how customisable their flashlights are (those that have the “Smart Light Technology”). Their “Transportation Lock” is actually a big factor as well.
What other brands do you guys recommend? I took a look at those 2 that appeared in this thread already. Astrolux seems to have a different target than me and doesn’t match my needs. Convoy is hardly available where I am located.
You list a 14500 (AA) sized and a 21700 sized light in your OP, what size you you really prefer?
As you’ve probably found, manufacturing is pretty much limited to China, there are some USA manufacturers but the lights are correspondingly expensive, that said, recommendations from members here will not be poorly built junk.
Headlamps generally more useful than flashlights, but you know your recepient and their likely use-cases better than we do.
What is your budget?
Where are you located? If you’ve time to wait, AliExpress sellers deliver to many countries.
Have you looked on zebralight ?
I guess you will get more answers if you edit the title or open a new thread
Well, technically the smaller the better but that P7R Core is still on the edge of being manageable and almost quadrupling the max runtime over the P5R Core is very appealing to me.
Yes, I understand the advantages of headlamps but here a flashlight should be more suitable.
I was looking for something around 50€/$ but I can do up to 80€/$ if it is going to be worth it.
Poland 
AliExpress is not an option atm.
BTW I enjoy the idea of supporting domestic buisnesses and I found a Polish company called Mactronic. They were actually the final contender to Ledlenser when I was trying to make up my mind. After seing a couple of YT reviews where they easily survived some serious tosses into a wall and proved water resistance, I can say that their reliability seems ligitimate. Similar to Ledlenser I also like Mactronic’s design and since the flashlight I choose will be a gift I care about the looks. However in the end I decided to opt for Ledlenser since at similar price point and specs they are much more customisable and have more thoughtful features. Have anyone ever heard of Mactronic?
I just did, thank you. They seem comparable to Ledlenser with their prices and specs. Although they don’t look “premium” in my opinion but I could definately get over that. Is there anything you can say from your experience? How reliable are they? Were you able to compare them directly to Ledlenser by any chance?
Yessir!
I am fixing headlamps for our local cavers community. Never had to fix a Zebra, already fixed few LL :)
I do know the L shape Zebra sometimes suffers from a broken front lens, but it is relatively easy to replace.
Also, it is nice that you have the option to choose emitter, temperature and optics....
Note that AFAIK they don't have a USB charging port.
I had 3 lights from LedLenser. Expensive, none lasted long.
They target maglite users who “think they will get something better”.
I hoped that too some years ago, believed the advertising.
My Maglites are more than 20 years old, they look badly beaten up scratched and
dented but still work perfectly.
Try and sell me ledlenser, I immediately answer, after my experience, never again.
In our family the oldest Chinese made LED lights are looking bad, bashed, scratched
and beaten. But still working fine. we are using LG or Samsung cells, which seem to last
countless charge recharge cycles with little capacity loss.