Ok, so I’m a little OCD. I’ve reviewed a few flashlights, and plan on reviewing more. But I did a runtime test on another flashlight overnight and today and it came up short. Just like my runtime tests on eneloops on my SG5..
Someone else did a runtime test on eneloops and came up with a figure that jives with manufactured specs on the SG5. So I guess I have a light that behaves bizarrely and it’s defective. Ok cool.
Well, during the last Wallbuys sale I bought a bunch of lights I plan on reviewing for the heck of it. Some there ain’t much info on, and a few that have some data. The light that has me concerned is the Fenix LD15, a light that has quite a few reviews out (though no reliable or tested data on low runtimes). I turned it on low last night, and thought I had somewhere near the 40 hour neighborhood, before it cut off. I’ve been taking pics at intervals so I can produce a runtime chart. The thing is, when I came home from work today it was pretty dead save for a few odd pulsings of light that came every 20 seconds or so. Throwing it on the charger, it had yet to recover voltage… but it read .85. About an hour later it was back at 1.11v.
Since the light ran out sometime while I was at work today, it clocked in well under 24 hours. Anywhere from 8 to about 18 hours. That’s not even close to manufacturers specs. The battery is a newer duraloop I got from the recent target sale that tested at 1900ish mah capacity.
So what say you? I’ve done quite a few tests on 18650 lights, all were somewhere in the ballpark. But the last 2 AA lights I’ve done, have fallen short. All tests are conducted with 3rd gen eneloops or duraloops less than a year old and none more than a dozen cycles on them.
Does anyone else do runtime tests this way, or does everyone use a formula? Why am I paranoid now that my batteries are either cursed, or I’m doing something wrong? Any experiences anyone cares to share? Or just discuss runtimes in general? Any big disparities from, major manufacturers other than lumens? How reliable is a formula for calculating runtimes. I do not like to give inaccurate data.
I may be in the minority here, but I could not possibly care less about run times. I know they are meaningful to those who use lights for work or some other necessary function. But I don’t do that. I seldom use lights for more than a half hour at a time and I’m religious about charging them before they get too low.
I hear you. I have so many lights, and rarely get into situations where I’d ever need to know this. So in practice, we’re both the same. But I feel I have to accurately relay data if I do a review of a light. People seem curious to know this, and I like to have the data on hand- because I know it’ll be asked. I actually enjoy doing the reviews, but the run time tests are a little tedious.
Fenix use 2500mAH capacity batteries rather than the 1900 version you used. They also seem to release or upgrade their lights with different generations of emitters over time. I'm guessing you already know this but make sure to compare your tests with data from the same model as efficiencies can vary.
But I agree, that 39hrs to "well under 24hrs" is a huge difference.
Thanks for taking the time to do the runtime experiments - it is something that seems to be missing from many reviews because as you say, it is tedious.
Might I suggest you browse through the reviews by CPF user "Selfbuilt" and see if you can find a light you have in common. Run a test and see if your results gel with his. I know CPF is held in pretty low regard by many here but there is a big database of info to draw from. (you could go direct to http://www.flashlightreviews.ca/reviews.htm)
This may give you a starting point in trying to figure out if there is anything amiss with your cells, charger or methodology.
I do generally run my AA lights pretty much right down until they start to fade simply because I prefer to fully cycle my NiMH when I can. However, I would put fresh cells in or take spares if I'm going to be out for a while. I use Eneloops or Imedions in just about all my AA lights as Duraloops are not common here.
How will you handle the power source variable? There are so many different cell types and capacities, never mind that a new cell will have more capacity than an older, well used one and that different cell types respond to high loads differently. Assuming someone takes the trouble to test it themselves, they are unlikely to get the same result as you. It might be more helpful just to mention that dividing the cell capacity by the current draw can give them a rough idea.
Long ago as a student, I used to manage an apartment block. At some point in the process many prospective tenants, mostly the younger ones, would ask what the electricity bill would be. I would usually respond with something like “I have no idea”. They would usually be puzzled by that answer, so I would then have to explain that the bill would depend on how much they used.
Maybe not identical results but they should be in the same ballpark. That's why I suggested comparing with other testers/reviewers if possible.
I guess if it were me I'd use my C9000 to test the capacity of a relatively new (less than 50 cycles) Eneloop and use that for my runtime tests. I'd also use a standard charge rate and (in the case of the C9000) an extra couple of hours after charge completed to "top off" the cell.
Eneloops hold up well under high load though at tests for low-mode runtimes this would be less important. They also seem to be the most common reference used by manufacturers.
You should be able to extrapolate runtimes from a 1900 to a 2500 cell.
Don’t get me wrong, I’m not stressing out of variances of a few hours or minutes. I understand that’s normal depending on batteries. But when a runtime is well less than half of a reliable manufacturers specs and you’re using a tested and known good battery, it’s weird. And especially when you try several different batteries. I just wonder how many people actually test runtimes- I’m guessing not that many.
Maybe I shouldn’t worry about it. Is it really that important?
Anyway I’m retesting the LD15 with another battery entirely. So we’ll see how that goes. I will be shutting it off this time, because I won’t be able to be home the entire time it’s running.
Yes, I am aware of all of those- and always use those as reference points. I checked many reviews out there for the fenix and the data wasn’t available. And when I do a run time test I compare it to known tests if there are any. Unfortunately many of the light’s I’ve done this on had little to no real data available on run times other than manufacturer specs.
Yes, I am aware of all of those- and always use those as reference points. I checked many reviews out there for the fenix and the data wasn’t available. And when I do a run time test I compare it to known tests if there are any. Unfortunately many of the light’s I’ve done this on had little to no real data available on run times other than manufacturer specs.
These are all rules of thumbs I use for my runtime tests. Newer batteries… eneloops, and less than 20 cycles. To be honest I don’t think it’s a battery issue really. But then again, my stories are really anecdotal and probably coincidental- so maybe it’s nothing other than two bum lights. But since there’s no data available on Fenix, I really have no way of knowing.
I think runtime tests may be helpful in certain use cases, but I’m going to play devil’s advocate here:
Why should you or I as a reviewer do runtime tests when no two sets of variables will produce the same results?
If at the end of the day, all we get is a result that approximates what others will experience, why go to the trouble?
If we do make the effort to use a “standard charge rate”, capacity test our test cells and spend hours on runtime tests why would we then fudge the data by extrapolating runtimes across differing cell capacities?
If ballpark figures or a rough idea are acceptable, as we both suggested, why would we do runtime tests? We can get ballpark numbers with a little simple math and save ourselves a lot of trouble.
I don’t think many people do. I had more than sixty lights at last count and I have never tested the runtime on any of them. It just isn’t important to me. Maybe I’m just lazy.
I think it’s great that you take the whole review process seriously. In a situation like you refer to above I think it’s important to show the actual performance of the light and point out that it differs significantly from what is claimed when you are aware of it. I don’t think it’s important to test every light to determine if it meets manufacturer’s claims. I doubt that many of us expect these claims are entirely truthful. You may want to consider just doing a casual test on lights (your definition, whatever it might be), and only do a formal test on the ones that vary significantly from the published spec.
I’m sure you know that the cells will be recovering a wee bit while you’re not home. :bigsmile:
My experience has been that the amount gained by "recovery" when you've run a NiMH cell down to under 0.9V and then let it rest is going to be proportionately quite small. I doubt it would have a major impact on your overall results.
Was the 1.17V measured under load or just across the terminals?
It was what the charger read when I popped in the battery. I have the IQ-328, FYI. So not under load. Yeah, I’ve found you’re right. You don’t get much more time. Anyway I’m conducting the test with a different battery, so I’ll see later.
Yeah, if lumens are usually off by a bit, I wonder what run times would be like if as many people did runtime tests on lights as they used a luxmeter on them. I’ve seen people correct reviews for being a few hundred lumens off on a 3000 lumen light before- like it’s even noticeable to most eyes at that high.
For me the runtimes are important.
I just need batteries and patience.
A luxmeter helps me, when the light drops to 50% I write, when drops to 10% i write, runtime test completed. (I like to take measure of intensity every minute, I can then make a graph., I love the graphics :bigsmile: )
Runtime is important. I also use lux meter for this. But generally when light intensity visually drops to my eyes I am putting new cell inside.
Either they have to invent better batteries, better drivers( I mean single cell drivers), or LED that will give its maximum at very low current consumption. Lets say 600 lumens at 0,5A
I mostly use eneloops- 3rd gen. The capacity is pretty much the same between the two batteries. If the run times are similar on the eneloops I’m currently using then, it’s not the battery. Most of what I’ve seen indicates that eneloops and duraloops perform identically.
Dividing battery capacity by tailcap current is a good reality check, and it’s a lot faster than a runtime test.
Determining candela is easy with a lux meter, and relatively few lights have this specified, but an amateur’s at-home measurement of output in lumens has even more variables than a runtime test, making it less credible to me. Even though few believe manufacturer’s lumen claims, we crave hard numbers :bigsmile: , so we get amateur lumens measurements. A reality check would be to compare measured emitter current with an output graph from Match . I don’t know how accurate Match’s lumen numbers are, but at least there would be a common reference point.
Run time numbers are important to me for planning power outage lighting, for hiking or camping to estimate battery and charging needs. If you are outwith only an EDC with you and happen into a situation where you actually Need it; nice to know how long you have before it goes dim……
Tailcap measures work well enough to estimate run times, and easier than waiting hours. Get yourself a meter, it’s easy.
The other trick manufacturers pull is the ‘ANSI’ run time to 10% output (….where it drops to under 50% in the first 10 minutes) A run time/output test will show this and is good to know even for those who only care about Lumen.
The only Fenix I have is an E21 (2AA) it draws 210ma on low and about 1A on high. I thought most Fenix drivers were efficient. This is a good one.
That's why I suggested comparing with other testers/reviewers if possible.
You may want to consider just doing a casual test on lights (your definition, whatever it might be), and only do a formal test on the ones that vary significantly from the published spec.
