I am trying to solve all kinds of possible (or impossible) problems and one of them is this:
1. You drive your car through a snowstorm and, at some point, road is closed and you can't go any further. It is night, very dark and kids are crying because they are afraid and can't see a thing. You have your blankets, water and snacks but how do you light the car until morning so the kids can calm and sleep?
or
2. No electricity at all for, say, 10 days. How do you light children's bedroom at night?
So the problem is: I need are a couple of lumens just to light a room or a car. The solution should stay on for 8+ hours without overheating and with no need for battery change. It also should be safe for unattended use in a kids room (out of reach of children of course).
The possible solutions that come to mind are:
1. Chemical light. (which is reliable enough to trust it will light up and holds for 8+ hours? These should not be China - no quality control - made because I don't trust Chinese with chemicals if they don't have a daddy over their head). On the other hand, a China made chemical light sold officially in EU or US is perfectly acceptable.
2. iTP A3 EOS (or iTP A2 EOS). Can they stay on for 8+ hours on low?
3. 22000 mcd DX keychain lights. Can one stay on for 8+ hours?
4. Typical 9 led flashlights. I forgot one of them on for more than 24 hours and it was still emitting light. But I hate to trust one of them as they are extremely unreliable.
5. ???
The solution should be budget enough to purchase at least 2 of them (so best if under $25 but can go up if needed). Also, I prefer the solution to work with easy to get AA/AAA batteries but it is not absolutely necessary.
I'm not sure but i think a 18650 light, not overdriven, in low mode can last 8 hour. I never made a test like this. Maybe you can calculate runtime with battery capacity and power consumption.
A R2 or a R5 with a (good) 18650 could do the job.
If we already have the BLF Zombie Edition i think that "moon mode" would be the solution
I stopped checking MRV clones thinking that "I have enough big 18650 lights" but if it has a low like this, I will check it again.
How do we calculate how much a flashlight will stay on knowing the battery capacity and the Amperage draw? If I know this, I can check every flashlight I have and calculate which can work for 8 hours.
A bit more expensive, but my R01 XM-L only draws 20ma on low so it should last over 100 hours on low and it can be recharged in the car if you buy the car adapter. Of course, you could always just find a lantern for this sort of thing as that is what they were designed for. Something like this, though I know you probably can't get this particular one in Greece:
I think we have to wait to have the Blf zombie edition...
btw, you can calculate (hypothetic) runtime dividing battery capacity by flashlight draw. Obviously you have to consider the REAL capacity of the batteries (Some 3000mah batteries are 2300mah) and the protection circuit that doesn't allow to fully drain your battery. Try to read some review on the forum and you can find many example.
I checked the specs of some of my flashlights and some of them seem to gladly stay on for many more than 8 hours on low (iTP A3, iTP A1, Sunwayman V10R, Fenix TK-35). Also, E1320 reports on dimeotane's thread that EDI-T P4 also can stay on "forever" so I think my EDI-T T11 with electronic infinite variable control will also do the job (with lower runtimes due to 16340 batteries it uses but still enough for 8+ hours).
And, I understood what I should understand by words alone... Mah = Ma per hour (thanks DavX), I hope I got it right this time
I think I will measure the Ma draw of some of my lights on low and publish it here so we can calculate some runtimes. Will this be useful to anyone?
I think we have a winner here. Budget, tiny, uses easy to get batteries, stays on for more than 10 hours and it has a keychain so we can hang it easily from a nail on the wall or a car's rearview mirror.
Actually, any XP-G AA light on Alkaline/NiMH/Panasonic Oxyride on low will go on for quite a number of hours. On photo lithiums it will probably be crazy. On a Xeno E03 XM-L, it is only 0.03A on a NiMH, enough light/spill to read a A4 sized magazine in total darkness. It will probably go on for 80hrs, and then slowly dim to unusable levels.
If you want runtime and ability to use primaries/NiNH, AA is better than AAA. AAA is optimised for size.
with 10 hour runtime, off a AAA, its going to barely be a a couple degrees above ambient.
A AAA Battery will have what, 1Watt of total energy? Spread that over 10 hours, thats 0.1watt of output. Assuming all of that turns into heat, thats 0.1 watts of energy that must be dissipated through the torch. What can we guess the thermal resistance of the torch to the environment to be? 15? 20 degrees per watt? thats a thermal increase of 1.5-2 degrees per watt. (talking centigrade)
If you were running high on a XP-G, say 3 watts of heat is being dissipated, then the torch will heat internally to some 50-60 degrees C above ambient, but off a AA, thats under an hours runtime off a good AA cell. (assuming perfect internal thermal design... hehe)