GREAT IDEA!
But……
To attach it to the back of the truck/trailer would need a nasty sized magnet. Too much vibration. Certainly a small magnet is really helpful.
I have plenty of these lights hanging around the house and work. Their magnet is just strong enough to hold the light. Cheap and effective.
There are some really good magnets out there. Check out the Emisar D4s review (TK).
4 x AA is too much for an emergency light. I would prefer 2 x AA instead. Everything else is great.
What about something flat like the Nitecore EA45S and you can run it with 2xAA or 4xAA?
Moonlight is definitely a must, because as an emergency light, you could leave it on moonlight for hours.
What is this emergency flashlight used for? What kind of reflector and range does a user need for these emergencies?
I had never seen that Maratac 1D/4xAA light before, it seems to tick most of the boxes of the emergency light of this thread. Reminds me of the BLF-version of the Lumintop SD10, that I indeed keep with some D-cells for emergency (as if I need a light in emergency, with 150+ of them already)
One thing essential for getting a BLF light done: a BLF member, or a few of them, who believes in it must carry the project, put loads of time in it, find and convince a manufacturer and patiently sit it out until the light is in production. Who is this going to be?
About the batteries: I suggested a few times elsewhere that a modern flashlight on AA batteries should not have 4 of them but 3 in series. It makes for a slimmer flashlight and you can use a very simple and robust lineair driver. This used to be impossible a few years ago but the voltage of the new leds have come sown so much that they can be run regulated at high output for most of the runtime of the batteries.
The only thing wrong with a 3xAA setup is that no serious manufacturer has made one yet with a high output modern led (suggestion: Luxeon V), the concept is just used with 3xAAA carriers direct drive on an oldschool XP-E led that has too high voltage to give real light. It will need a lot of convincing to get a chinese manufacturer make something that has not proved itself before.
How do you safely charge multiple AA NiMH cells inside a flashlight?
You just use multiple small 1A buck converters to charge each of the AA cells individually.
Unlike with most of our lithium-ion lights, charging 4x cells with USB is quite easy.
But how do you do that if they’re already connected in series?
You just use an internal charger.
You do isolated DC-DC converters.
They aren’t too expensive to implement in large bulk quantities for a flashlight.
Remember low temperature considerations for emergency lights. Nimh does pretty good, but a lot of people in my area will only use lithium primaries in real outdoor emergency things.
There are going to be “really stupid people” issues with batteries. The flashlight has to come with either sealed access for the batteries or no batteries and a warning that do not charge unless you install rechargeable batteries. Prefer the first one. Seal them and only let people like us with a method to get around it.
Did I mention really stupid people? They plague humanity.
I’m contacting Sonfir.
I know a thing or twelve about manufacturing and marketing.
To a small company, this could be something that puts their brand on the map. After all, the enthusiast market is maybe a fraction of a percent to a mass market flashlight like the one we are suggesting. I can see the potential of millions of units.
I’ll help them conceptually, but I’m not going to do their legwork. The only thing I want from them is a knock out group buy for our members.
I’m retired and I’m enjoying being lazy…. 
Interesting idea.
I like the idea of NiMh batteries because of the longevity of holding the charge.
And….Sofirn got the first email.
Let’s see if they are interested.
A red light in the tail would make it safer for walking down unlit country roads at night. Rather than strobe modes, how about just a single flash every second or two, as a locator beacon (can get slower as the batteries die). Does it need 1000 lumen? Surely 500 lumen is adequate if its for emergency and not a light-all throw further flashlight.
I would say with lower lumens you need more throw to have a useful light source. It isn’t hard to get ~1000lm from a 4xAA light these days. That milestone was reached years ago and with new LED technology it is getting even better. But, I wouldn’t be opposed to a muggle mode that only goes to 500lm and is the default mode from the factory. That way, only more advanced users would ever see ~1000lm with the accompanying short(er) run time.
I’m debating what is more important….a magnet on the tail or lanyard loops and led.
I can’t see how to get a flat tail AND led AND magnet AND lanyard loops. That’s one busy tail……
The magnet looks like the first sacrifice.
Well, if you design it like the old SRK lights, the lanyard loops are on the sides. That might even be a selling point, since a lot of people are familiar with SRK style lights and I don’t know if it has ever been done in a 4xAA size before. 
Agree.
An emergency light should be a flooder. Or very soft hot spot with easy spread into flood. It won’t help much if the light has a blinding hotspot while trying to fix a flat or lighting under the car hood.
An emergency light should be measured in hours runtime, not which planet it can reach for an SOS.
I use the tn4a as a base sample.
Strobe(1150 lumens/150 minutes),
Turbo(1150 lumens /56 minutes),
High(550 lumens / 150 minutes),
Medium(139 lumens / 14 hrs),
Low(15 lumens / 93 hrs),
Moonlight(0.5lumens/80 days).
In theory, 500 lumens for 3 hours and 140 lumens for 93 hours looks very good for an emergency light.
150 lumens is enough to change a tire or look under the hood or fix something close up. 500 is better looking for long lost relatives under the crawl space or lighting on a forest walkabout.
1200 lumen capacity with thermal activated step down will confuse muggles.
“I was trying to blind my neighbors and the light power changed. My light is broken.”
Don’t take it away, just make it a three quick click access. First and normal access, low, medium, high.
Link? Or pics?
Definitely think that a built in lanyard loops are useful. Particularly to boat people or someone who wants to tie down a light to something for extended use. Like camping?