While surfing the Internet add poped up for the military tactical T6-2000 which was super bright and better than pepper spray for blinding an attacker. It claimed to put out 2000 lumens, so I did some checking.

Background:
LED's put out about 7 times the light per watt than Halogen bulbs.
The ones you see on the checkout counter at the hardware store have multiple low power LEDs.
There have been several recalls of LED flashlight because the flashlights can heat up, smoke or melt when turned on, posing fire and burn hazards.
See Recall: BJ's LED flashlight and battery set—Fire hazard

You see a lot of high power 1000+High output lights:
The Ad I saw said the T6-2000 got 2000 lumens.
Most use a T6 bulb and one or more 18650 3.8 V Li-ion batteries
Many only work for a couple of minutes at high power.

18650 3.7 V Li-ion battery:
22000 -24000 mAh $20
34000 - 50000 mAh $20-35
They are not all the same size.
See Battery test-review 18650 summary What is the best 18650 battery?? - YouTube
Best: Panasonic, Xtar SenyBor

Noob with 11 questions on 18650 batteries- can you answer any?

T6 LED:
At What is the max achievable lumens from a CREE XM-L T6 LED? they say it's 900-1,400 lumens.

UltraFire CREE XML T6 LED is supposed to be 1600 lumens
At Amazon.com: Customer Reviews: UltraFire CREE XML T6 LED Flashlight 5 Mode Zoomable Torch (Flashlight ONLY) several people said it wasn't that bright.
One said 'My led 139 lumen maglight from Walmart does a slightly better job than this "1600 lumen" flashlight. ' Flashlight Review: Noctigon M43 Meteor 6300 lumens! Worlds Smallest & Brightest of 2015? - YouTube
It has a fancy complicated user interface.
At the end of the video he compares a bunch of flashlights.

Links:
Light Bulbs in Home and Garden here.
10 Best LED Flashlights Reviews - Top 2016 LED Flashlights - Best Reviews Amazon.com: highest lumen flashlight