How long do your outages last, and for how long do you want to be prepared?
I would say that lanterns are ok for outdoor use, but indoors, ceiling bounced flashlights are more comfortable. The problem with lanterns is that they typically emit too much glare, and a poorly designed lantern will emit more glare than another, and the higher the output, the more glare regardless of how well it is designed.
500 lumens in a lantern is a poor choice IMO for a number of reasons.
1. regardless of the design, it'll emit too much glare
2. @ 500 lumens, it'll run through batteries, too fast except for the shortest of outages, it'll probably be a 4x D cell lantern.
2a. on alkalines, it'll maintain that output for less than an hour, if it could get that high at all, and then rapidly drop to 100 lumens, from where it'll gradually decline giving less and less for hours.
2b. on rechargeable 8000-10,000 mah D cell NiMH, you might get 3-4 hours, @ 300 or more, and then it will very rapidly decline.
I think that StarHalo said it best when he said something along the lines of "100 lumens ceiling bounced light is about where the two points of having a comfortable amount of light and economy of batteries intersect."
I once wrote a review of the Walmart
Ozark Trail 300 Lumen Lantern
It is a low cost ($14.97) single Cree XB-D emitter and runs on three D cells.
It has a high and low and just uses two different resistors.
It has a CW tint, but not a terrible blue. For a couple of dollars I picked up a warm/NW XB-D and it was very easy to swap it in.
What really impressed me with this lantern was how long 3 D alkaline cells can power an LED lantern under low loads. I imagine that just about any 3D cell lantern that starts at 50 lumens or less, will run for 7 hours a night for a month. In other words, each D cell (under low loads) will have a similar capacity to a 18650 cell.
--------------------------------------------------------------
Actually I was wrong... under low loads, the alkaline D cell outperforms a 3400 ma 18650.
---------------------------------------------------------------
For the
power outage thread I reviewed HKJ's battery reviews that presented run time, and calculated capacities of different batteries under different loads.
Follow the links for more information of how the D cells performed
compared to 18650's and
compared to eneloops and D NiMH cells.
In short:
The D cell at 0.200 amps delivers 17.429 wH
The 18650 at 0.200 amps delivers 12.123 wH
I guess that at about 600ma they are about equal in deliverable watt hours. Below that, the alkaline D cell is up to about 1.5 times better, and above that the 18650 can be up to about 3 times better.
A cree XM-L2 emitter driven at about 0.200 amps ( 200ma) will deliver about 70 lumens
The reason that so many cheap lights use 3 AAA batteries is because their working voltage of 3.6 - 4.5 volts is close to the working voltage of LEDs, and it is cheaper and easier to buck the voltage down or use a simple resistor, than to boost the voltage up.
So I would suggest that if you get a light or lantern in the 3D format, it would be more efficient than in a 2 or 4 cell format.
Additionally if you want to use alkaline D cells, look for one that uses a Cree emitter (or other highly efficient emitter) and has a setting that starts somewhere less than 80 lumens. Then you'll get some significant run-times. You are looking for a setting that is less than or equal to 200ma.
Some info on emitters:
found what I believe to be fairly accurate information.
1. Cree 5mm round white LEDs are about 30 lumens per watt efficient
2. Cree surface mount LEDs are about 65 lumens per watt efficient
3. Cree XM-L2 LEDs are about 116 lumens per watt efficient even when driven at 3 amps!
The trick is if you want to get long run-times, is to start low, and stay low. If you run it high until it drops off and then switch to low, you already burnt through a lot of the battery's capacity and you won't get the run time you would if you started low and stayed there. Additionally, lumens are additive, so if you want 120 lumens, 3 x 70 lumen lights will run at least 1.5 times as efficiently as one 210 lumens light. Meaning that you'll get 4.5 hours from the three, for each hour from the one.
I hope that you found this info helpful.