Cheapest way to have emergency lighting? Im talking fuel vs battery ?

Many of us have tons of batteries, but i doubt many keeps all theirs 100% charged ready for emergencies. Those events happen when you least expect it. Gas lamp will be the most practical and cheap solution imo, especially if you able to run it of a 20lb gas tank.
Perhaps I'm the outlier, but I do keep my lights stored with batteries all charged to 100%
Recently I pulled out from under my bed a box of lights, stashed there 2 1/2 years ago. They all worked.

Typically before a significant storm hits, I'll charge up battery packs for phones, and top off the batteries in my most used lights. Otherwise, even at my most most unprepared state, I'd be capably prepared for a couple of days in the least.

Also, I'd like to remind others that if you use your car battery to charge up your cell phone, or 18650 batteries, a 20 minute round trip to the store for supplies, will likely recharge your car's battery with its alternator.
 
Hurricane Ian survivor from Fort Myers Beach here.

I've been through numerous hurricanes before, but this one was different. Our building was designed to take on a storm like this, and it performed better than the engineers thought it would, but we still got nailed. We had multiple large automatic generators which power the entire place, even the fountains and landscape lighting...all of them were damaged beyond repair. The electrical distribution boards got wet with salt water, water pumps and other infrastructure did as well. Still no ETA on when I can move back home again. About half of my coworkers who live on the mainland also lost their homes.

So...I've had a lot of practice with emergency lighting over the past few months. While I have all sorts of fun flashlights, the real workhorses of the show have been the Duracell lanterns from Costco. Both the 4D & 8D models (NOT the Hybrid models, as those have a terrible CRI, terrible color temperature). Also, the Mr. Beams MB530 lights.

The MB530 are motion lights, but they put out a dim glow when it's dark and go to full brightness when they see motion. We had these all over the place even before the storm. In normal times, I'd go 1-2 years between battery changes on these. With the generators knocked out, these came in handy for times when we didn't have the lanterns going. When it's pitch black, their dim glow lights up the room well enough to see where everything is. The bright light activated by motion is very bright, and useful to locate one of the lanterns.

I don't know that there's a cheaper way to do emergency lighting than this. The Duracell lanterns are sold in pairs at Costco for $19-$25, so $9.5-$12.5 each for the lanterns. D-Cell batteries are $1.15/each at Sam's/Costco, so $4.60 in batteries for the lantern. They say these will last for 60 hours at 250 lumens, or 240 hours at 65 lumens. $4.60/60hrs=$0.076/hr, $4.60/240hrs=$0.019/hr. Certainly not as cheap as regular lamps on grid power, but hardly burdensome, for a very low up-front cost.
 
. They say these will last for 60 hours at 250 lumens, or 240 hours at 65 lumens.
According to the ANSI FL1 standard:
Runtime is defined as the amount of time, rounded to the nearest quarter hour, until output drops below 10%.
250 lumens, and 65 lumens, is the startpoint, not the end point.
As the batteries drop in voltage, the lumen output drops. Typically, more than half of the runtime is with the light producing less than half of the initial output.
 
I'd fully agree that these aren't fully regulated, but they've served us very well for multiple months now. The thread title is "cheapest"... fully regulated isn't going to be cheap.
 
As someone who has lived both off-grid and through extended power outages (>1 week) due to hurricane/storm damage, I will say that if you don't have power, unless you are an emergency service provider working though the night, you very quickly learn to live by sunlight as much as possible. So, again, the questions have to be asked:

1. What do you need to light?
2. How brightly do you need to light it?
3. How long do you need to keep it lit?
4. Will you need to move the light?

For power outages of 1-2 weeks, most people will find it expedient to simply keep an extra pack or two of lithium primary cells around, and adjust to accomplishing most tasks during the daylight hours.

If you are running an aid station or the like, you probably have portable power generators.

A few years ago, my mother had a whole house natural gas fueled generator installed. The neighbors were pretty envious when the next storm hit and the power to the whole neighborhood went out. :D She lets them come over to charge their cell phones and make tea.
 
Battery is cheapest for emergency power in ways that have nothing to do with cost. First, it doesn't make noise. A gas generator to run lights makes noise which attracts attention from looters during an emergency. Doesn't matter how cheap your light or power source is compared to something else if you can never use it because it'll get stolen. Battery lights don't produce deadly gasses that need to be vented to outside. Gas lanterns, candles, and generators all produce fumes and carbon monoxide that requires them to be used outside or with proper ventilation. This ventilation may cost added heat in the winter or give an open window for a thief to break in. Worst case scenario, someone dies of carbon monoxide poisoning. Gas appliances are not as portable as l.e.d. flashlights. This may be an issue if the emergency you are experiencing requires you to evacuate quickly or otherwise be ready to run or travel. It may cost you time moving something bulkier and heavier that can cost you time you'd otherwise have saving something or someone more precious. Lastly, gas is not renewable. I can pack a Luci Lux Pro or Base lantern in a pocket and have a light that I can solar or USB charge daily for an extended period. With gas, during a disaster, supplies dry up and trying to get near supplies puts you near desperate and dangerous people.
 
As someone who has lived both off-grid and through extended power outages (>1 week) due to hurricane/storm damage, I will say that if you don't have power, unless you are an emergency service provider working though the night, you very quickly learn to live by sunlight as much as possible. So, again, the questions have to be asked:

1. What do you need to light?
2. How brightly do you need to light it?
3. How long do you need to keep it lit?
4. Will you need to move the light?

For power outages of 1-2 weeks, most people will find it expedient to simply keep an extra pack or two of lithium primary cells around, and adjust to accomplishing most tasks during the daylight hours.

If you are running an aid station or the like, you probably have portable power generators.

^ This.

For basic, low-powered lighting only, my own choice is:
  • Malkoff M61LL (80-lumen) flashlight -- sufficiently bright for seeing well enough during, say, picking through the rubble (in the dark) after an earthquake or storm, yet frugal enough to last many hours on one cell's charge;
  • 18650 Li-Ion cells, a dozen+;
  • Easily fits in the corner of a daypack (2 flashlights, 2 8-packs spare batteries, 1 charger+cord);
  • With care, could a couple months on ~2-3hrs/night of use;
  • Presupposes re-adjusting preconceptions of "need" for post-sunset lighting.
 
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