Do it have any overheating problem using 14500?
If you can test runtime with 14500 will be great! 8)
Thanks for the measurements.
Runtimes later once cells charged again.
14500 - High - 4.18V
This is done using a solar cell inside the lightbox. Its response may very well be non-linear I've not properly tested the thing as I don't have any calibrated light sources to check it against.
74.8 microamps =1748lux on lightbox - roughly
It is down below 50% by two minutes. At three minutes the head is warm - but there is a fan on it as I always do with 14500 lights. Down to about 25% in three minutes.
326 lux=17.2 microamps
I reckon that usable light is produced down to around 1.5 microamps
At 6 minutes down to about 14%
8 minutes 12%
26 minutes - just usable light. Down to 2% of initial fearsome output. Call it 6 lumens which it may maintain for a while. Will post graphs when the runtimes are complete.
32.6 microamps at switch on - again cell at 4.18V
Runtime should be a little more sensible this time - it is pulling a third of the current so the cell will be able to release more before the voltage drops to uselessness.
10% below peak at 4 minutes.
Now down to 20%. Looks like a backpack full of batteries is going to be needed for this one. It is very, very bright - just not for any length of time. Will do runtimes on NiMH as well to see if they are any saner.
Thank you Don for sharing all of these details...I really appreciate your efforts.
That's a seriously steep dropoff on high, isn't it? Sounds more like a match than a flashlight. I always like getting data in on new lights. How many minutes did you have it before you thought of taking it apart and putting in some resistors?
About ten seconds after I attached it to a meter!
14500 High.
Two Minutes to 50%!. Two Minutes!! I mean, TWO MINUTES!!!!!!!!!!!!!!
It is still producing some usable light at 30 minutes but these are unprotected cells. I mean - TWO $%@^$^%*&*& MINUTES!!!!!!!!! Even by crazy short runtime incan standards this is daft - you'd need a sack of cells just to show it off.
Low is marginally saner. Not sane mind, but not quite as crazy.
A whole 8 minutes and twenty seconds to 50%. Whoop de doo! Light a candle! Because at 40 minutes you are going to need it.
This light just has to be the photon extruding equivalent of a drag racer. But I don't know of a standing start quarter mile blinding for flashlights.
It is very, very bright.
Briefly!
The battery is being driven hard, but not hard enough to lose all of its capacity in a couple of minutes (unless it's just a crappy battery). What would explain that kind of drop-off? If the LED was heating up that much it seems like it would turn blue. You'd have to go out of your way to design a driver that would do that, well, unless it has some kind of thermal protection built in that is being triggered.
Will rerun with a protected cell. However, it is quite possible that at those currents the 14500s I'm using have a dramatically lowered capacity anyway.
2C is pushing things for a cheap Li cell.
I'd guess their true capacity at saner current draws is around 500mAh at best. Could easily be a hundred or so mAh at these currents.
It didn't go blue so the LED wasn't overheating thought the driver may well have been.
On a new protected cell, at 3 minutes on high it is down 10%
Nineteen minutes - down to 80%. This is looking a lot better - again with a 14500 on high. It is not all that hot, but there is a fan blowing on it. Will try the hand torture test later.
29 minutes 5 seconds to shutoff - which implies a capacity in the close ballpark of 900mAh. Should get over an hour on low with a 14500. Better redo all the lithium cell measurements as well as it did make a little more light at startup than it did with the grey cells.
May get two hours out of it on low which would be not bad for over 100 lumens from a 14500.
1 hour 21 mins to shutoff
14500 low
Respectable for the amount of light involved.
Since an NiMH Eneloop contains about the same amount of energy as a 14500 (At least a good one), the overall outputxtime should be the same. It produces slightly more on an Eneloop than on a 14500 on low so should run for about the same sort of time. Since there is no protection circuit, it'll run for longer - or at least I am expecting it to.
Don do you think that you just got a light with a bum circuit....two minutes is not much at all to 50% which to me sucks but then again might be a driver issue. Thanks for the review and taking one for the team.
Yikes, less than 2 hrs on low.... I wish shipping wasn't so expensive from here, I would sell mine even before it arrives.
Nah - broken cell. Real output much better for longer. Half an hour at over 200 lumens or an hour and a half at over 100 lumens on an actual working 14500