He lives about 100 meters from a small wet-weather creek. During short periods of intense rain (think very heavy thunderstorms, or remnants of a hurricane moving across the area) said creek can rise fairly quickly, sometimes enough that some water may flow down the steps into his basement.
As long as utility power remains on his sump pump is fully capable of staying ahead of the flow. If utility power fails, he uses a generator to power the pump & other stuff.
If the rain event occurs in daylight he can see the water as is approaches his property, giving him plenty of time to prep the generator.
There's a streetlight between him & the creek that allows him to see the approaching water level at night, unless utility power has failed. This is where a good flashlight can be utilized.
I'm thinking a 100 meter thrower with minimum/no spill, on the warm/yellowish side to punch through rain & humidity haze the way fog lights penetrate.
Long runtime isn't an issue, only needing sporadic 10 - 30 sec. bursts to see where the water is.
H/M/L UI would be fine. No other modes needed, although moon would be OK. If blinkies, they need to be well-hidden.
Reasonably waterproof, just to tolerate a little exposure to rain.
He has no experience with Li-Ion but is a techie by temperament & could be easily educated. I'm thinking if Li-Ion, on-cell or onboard USB charging. If Li-Ion, LV protection is a must.
This light might sit unused for months or years though, so I'm thinking lithium primary cells might be a better option. He tests the generator periodically, and could incorporate flashlight testing/charging into his generator test regimen.
So:
good 100 meter throw,
no/minimal spill,
yellowish output to penetrate heavy rain/humidity haze/fog,
easy, simple UI - blinkies not needed,
minimum, periodic runtime needed on High,
simple cell use/maintenance,
needs to work on a moment's notice after long-term storage.
Thanks for your assistance, all.