Good evening
Can you recommend a lantern that has an autonomy of more than 25 hours at full power, I am looking for a great brightness
thank you for your help
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Any specific reason why 25hours? Is that what your current lantern does?
How bright is great brightness?
What’s your budget?
Back of the envelope calculations:
26 hour runtime.
175lm/w system efficiency
700lm output.
= 104Wh. Which is about 6-9 18650/21700 cells depending on capacity.
2000lm for 26hr requires nearly 300Wh. Which is 16 21700 cells.
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Welcome on BLF !
Yeah, im new into flashlights and i don’t know much about lanterns… but “25 hours at full power” look somewhat mission impossible… !
Maybe some other member can help you… have a good one… !
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Thank you for your help and your kindness
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As comparrison, this is a 300Wh powerbank. Maybe you can use a smaller one with a lantern.
https://budgetlightforum.com/t/review-ctechi-gt300-most-affordable-lifepo4-portable-power-station-300-450w-300w-h-lifepo4-110-220v-out/217491
Maybe you ask for a lot? But this is depending what you understand with “great brightness” .
Also a lanter sheds light in all directions. Put it next to a white wall or an aluminium half zylindrical reflector you can safe half of the lumens.
Thank you for your help
I need to light a bathroom for 25 hours once a week because there is no light inside and no window either
I don’t have a budget
Do you have in mind a model ?
Get a battery powered PIR sensor LED lamp from eBay/AliExpress then it only lights when you’re in there…??
I cannot use sensor 
regarding your calculation do you have a model for me ?
My calculation was merely to show that “great brightness” For more than 26 hours is asking a lot.
I’m not aware of any lantern that uses 6x 18650 cells.
Why do you need to light a windowless room for 25 hours continuously one day a week? I don’t understand why a PIR sensor doesn’t work for your needs…?
Is the building off-grid?
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Because it’s shabbos ( jewish holiday every week from friday night to saturday night ) so I cannot use PIR sensor
inside the toilets there are no plug
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Uh, religion makes some things complicated.
Here is an article form a sensor company about this:
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Okay, I understand now.
Unless you have a massive bathroom, poor eyesight, or have extremely dark coloured walls, you probably don’t need 700lm.
Fenix claim their CL30R lantern will do 100lm for 38 hours on 3x 2600mah 18650 cells.
Not seen a runtime test at a similar level, but a BLF LT1 might also work.
Any light with 4x 18650s or 3-4 21700s and a suitable low mode, should work, just tailstand it with it shining on the ceiling.
The difficulty you will find is the lack of low-mode runtime charts done in reviews of lights, especially bigger lights with multiple batteries.
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How about a candle lit by matches? This strategy will help to mask the stink as well.
i do not think he is allowed to touch a fire extinguisher either, or even put out a fire, i did recommend a propane lantern, but then i read this thread (2nd out of 3 identical) and edited my post.
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A BLF LT1 running at 100 lm is plenty bright to use a restroom, and runs for about 34 hours per charge when using 4 x 3000 mAh cells. More like 40 hours when using 3500 mAh cells.
It can then be plugged into USB (or a USB power bank) to recharge itself. Or it can just stay plugged into USB and run indefinitely, even without batteries inside. Some people run a LT1 several hours per night entirely off-grid, using a small solar panel to charge it during the day.
For a battery-powered LED light like this, the light does not come from fire, and no sparks or fire are created or extinguished when turning the light on and off with the switch. It does not connect or disconnect power; instead it simply allows more or less power to flow, much like how tipping a glass of water allows the water to flow faster or slower. It never truly turns off, even in the “off” mode. Because when it’s “off”, it just reduces the amount of power to a tiny trickle, and turning it “on” lets it trickle faster. This then makes a luminescent phosphor glow, like glow in the dark paint.
Another option is to leave it on all the time, and simply turn the brightness up during use, then turn it down again afterward.
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So there are multiples…HUH? I thought my brain was skipping or something… 
Hello
can you recommend a lantern that has an autonomy of more than 25 hours at full power, I am looking for a great brightness
thank you for your help
Honestly i can’t think of one that will run at full power for 25 + hours from internal battery, you’d need an external power, however very few lanterns have a jack for external power. not a charging port, but a jack that is made to power the light externally. most lanterns will run that long on low power, but it is not
BTW, welcome to BLF
Would you consider using multiple lanterns for the bathroom, and having two sets?
It would be hard to have “great Brightness” as in equivalent to the AC powered lights for 25 hours on batteries. If you could accept light that would allow you to see what you are doing well, then a pair of 250 lumen lights may be fine if placed correctly in the room… Having two sets that could run ~12 hours per set would make it easier to find something. Just swap them out half way through the time period.
Is there some reason that the lights cannot be switched off when no one is using the bathroom… Turning them off 25% to 40% of the time would also help tremendously.
Again, battery powered lighting, without huge batteries, will not get you AC powered light levels. Consider that a single 12 watt LED bulb on AC (100 watt equivalent) is something like 1600 lumens. So what do you mean by “great brightness” ?
EDIT: How big it the bathroom?
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