energizer L91 direct comparison in all modes?

[themaxx69]

I've been doing a lot of reading comparing L91s to CR123s, and I know there are quite a few threads on them, but I have yet to run across some direct comparison for all modes of a light between L91 vs CR123.

All of the reviews that I read would show run times on hi with L91s but not all modes. On the other hand the CR123 run times would be shown in all modes. My point is, from what I have seen in some high mode comparisons of L91 vs Cr123s, I think the L91s look better. What I don't see is how they compare at lower light outputs.

Is there some reason there isn't more comprehensive data on the L91 run times compared to CR123? Or am I just missing it?

 

[AnAppleSnail]

Is there some reason there isn't more comprehensive data on the L91 run times compared to CR123? Or am I just missing it?

The L91 is about half the voltage of a cr123, so it's still basically a AA. Medium and Low will have similar discharge curves to the AA, but longer. Note that the AA sucks worse at high drain.

 

[Lynx_Arc]

Not sure what you want, it is like comparing apples to oranges unless you use the same light or comparing two lights that put out the same lumens using the same emitter you don't have a direct comparison as the batteries are that much different as to effect all the calculations. 123s have more voltage but less capacity and don't have to drive the boost circuit nearly as hard to get the same output which usually results in more efficiency but if a light uses 2AAs it would have the advantage in higher voltage using lithium primaries over the 123 vs 1AA.
So.... 1AA vs 123..... 2AA vs 123 or what? how "low" of a mode you looking for, and what type of lights you looking at?

 

[PeaceOfMind]

It's hard to do this kind of comparison fairly in a real light. However I believe the relevant points here are:

-CR123s @ 3V are much closer to the voltages required to drive an LED. Changing voltage is not 100% efficient, and the more you have to change the voltage, the less efficient it is. Stepping voltage down is more efficient than stepping it up. AAs such as the L91 need to be stepped up quite a bit and so single AA lights are going to be inherently less efficient than single CR123 lights unless someone invents a 100% efficient Boost converter to step up the voltage with no loss

-Capacity wise the cells are similar in terms of total power stored. This can be seen as follows:

L91 is rated at about 3000 mAh, with a nominal voltage of 1.5V. 1.5V x 3000 mAh = 4500 mWh (milliwatt hours - remember Power = Voltage x Current - i.e. Watts = Volts x Amps)

A typical CR123 is rated at about 1550 mAh with a nominal voltage of 3V. 3V x 1550 mAh = 4650 mWh

Thus we can see that the CR123 stores a bit more total power.

-Both an L91 and CR123 are Lithium primary chemistry and could be reasonably expected to have similar internal voltages and discharge curves. However, as mentioned, the L91 voltage needs to be stepped up in a single cell application, which requires drawing more current from the L91, which creates more power loss because of internal resistance in the cell/elsewhere. The Power Loss = I^2 x R where R is the internal resistance, so driving the battery with more current I creates more power loss .

So, from a purely theoretical point of view, although the L91 and a CR123 have similar amounts of power in them, the CR123 will have an edge in a single cell application in an LED flashlight. If you start to look at multiple cell applications/etc, the balance of which is more efficient will change.

I'm not sure what you hope to learn/gain by comparing these two types of cells, but hopefully the above will help.

 

[themaxx69]

Awesome, thanks. Like many have asked before, I'm trying to pick the "better" of the two batteries, for me. Single aa/123 & 2 aa/123 size lights. D10/EX10, PD20/LD10, Quark aa/123 etc.

But again, none of the reviews I read show L91 run times on anything other than high mode, why is that. When I looked at the d10/ex10 review, the L91 looks to be almost equal or to me seems superior than the cr123, on high. That is where the comparison stops. If the lithium far exceeds a duracell on high, wouldn't it do so in other modes?

Ultimately, I would prefer a AA light, but if cr123 give me a "big" increase in brightness and run time over a L91, than I would use it, but in all the comparisons and cr123 vs L91 threads, I don't see that info. Has nobody done a real comparison of an AA light with L91 vs cr123? Or my next setup which would be 2xL91 vs 2xcr123?

When looking at say, the quark AA2 vs the 1232 , the AA seems to take the edge except for the brightest mode, and that's only by a bit and without a lithium.?????:duh2: I also read a lot of posts that stated that isn't much noticeable difference in brightness when comparing some higher lumens, like 180-210 or 130 -180.

Looking at some other reviews with a quark mini AA and LD10, again the L91 on high seems to be right around a CR123 or exceeds in in run time.
I thought most people were saying the CR123 beat the L91 in run times? Is this true in most brightness levels or no? Doesn't look like it is on high with these flashlights.

Just went to nitecore website, and they list d10sp at 145 lumen for 1hour, ex10 145 lumen at 90min. So from previous data, L91 seems to exceed the CR123??? :thinking:

 

[alpg88]

lithiunm AA can safely be discharged at 2a cont.

 

[PeaceOfMind]

The comparisons you are trying to make are a bit confusing since in many cases you're trying to compare lights with different circuits and lights which give different amounts of output and drive current depending on the battery input voltage. This is not a valid comparison

The Nitecore D10sp vs EX10 rating you are looking at is not likely rated with an L91, it's probably rated with a high capacity NiMH or whatever they could get the most runtime from.

In some series of lights one may win and in others the other may win. As stated in my earlier post, they have pretty similar actual power capacity, and other factors come into play.

If you want to make these comparisons, stick to comparing lights with the same circuit for each the CR123 and AA version such as the Quark AA and Quark 123 (but not the Quark 2xAA and 2x123 which have different heads) and compare them on modes with the same drive currents for each battery (ex. the Quark AA and 123 on 'high' but not 'turbo' which uses a lot more drive current for a CR123 input voltage)

 

[themaxx69]

Thing is, you can compare similar lights, that's what I asking. If for example the brightness modes on the d10 and ex10 are "close" to each other, than you can do a comparison which is exactly what I'm look for and I am totally surprised, with all the question about L91 vs CR123, that no flashlightaholics have done that.

It's a valid comparison. I'm looking to see which battery would provide greater run time in various levels, when both levels are fairly similar. I'm not trying to compare a d10 to a freaking tk40 here.

Looks like I will have to promote myself and run some test. I know there have been a lot of people asking about L91 vs CR123.:rock:

 

[PeaceOfMind]

Yes, but if you're going to go to the trouble of doing a comparison, why not compare the same head on each battery on the same level. i.e. why not compare Quark 123 vs Quark AA on Low, Med & High (but not Turbo) rather than two different lights. The Quark 123 and AA use the same head and have the same drive current on Low, Med & High, so this is a more valid comparison rather than a mostly valid comparison such as D10 vs EX10.

Not trying to discourage you or argue, just suggesting that if you want to really compare these two batteries, which have very similar amount of power stored in each, you might as well compare them in a more accurate way so that you don't mistake variations in the different lights for variations in the batteries.

And, I do feel I need to keep emphasizing this, there's a lot more that comes into play than the battery itself. You won't be directly comparing the batteries, you'll be comparing how an individual light's circuit performs on a given type of battery, which is a similar but not quite the same question. I truly believe that this is a light by light basis type of question you are asking, and there will not necessarily be a universal "Battery type X is always better" type answer.

Just to clarify a bit further, let's say you tested an EX10 on CR123 vs a D10 on an L91. Let's say, hypothetically, that the D10 ran longer at a similar drive level. The conclusion drawn from the test would not be "L91 is better", which seems to be what you're looking for. The correct conclusion would be "The D10 performs better on L91 than the EX10 does on a CR123". That's really my point.

If you decide to run any kind of run time tests, please post the results, they are always valuable to have, regardless of what conclusions you choose to draw from them.

Cheers.

 

[themaxx69]

Excellent info, thanks.

Still, for me at least I'm looking for a single AA/cr123 right now, a double later. So I want to look at some of the I mentioned earlier and find out which has best "combination" I guess, of run time and brightness, the lights with L91 or the lights with CR123. I understand now that individual light will function differently, but what I don't understand, again, is why are there comparisons, like this thread, here , that show info on the lights in only high mode. I'm looking for info on high, med, low etc. There is info on cr123, aa, lipo, nimh, but not the L91. There is the prob, kind of the original question. It's like a teaser, here's the light on high, but we wont show you the rest. :mecry: And there are other comparison threads that are the exact same. Why only run times on high with L91? Is it cause they are expensive? I found L91 to be almost the same price as CR123.

 

[PeaceOfMind]

I think the reason you don't see more runtime tests is:

-Cost of batteries, and with non-rechargeables needing to waste an entire set of batteries for each test on each mode run

-Doing runtime on lower levels takes many hours or even days or weeks. Picture how long it would take to do runtimes for JUST one light on three levels with three different battery types. That's 9 separate tests, with some of them on the low levels taking many hours or days or weeks. It'd be awesome to see this data, but it's just very time consuming to get. I have a lot of respect for the people that do get us this type of data. And even these determined people are probably not willing to spend 2 weeks getting data for just one light and so they get representative data for basic comparisons and we're left to manufacturer specs and estimates for the rest.

-Equipment required: To reliably tell when the output is dropping, some sort of light metre or light box is needed. This either needs to be monitored constantly for the entire test to see when it hits a certain threshold or hooked into a computer

So basically, it takes equipment, money and time and I'm sure if it didn't than everyone would be doing it and we'd have tons of data. It's unfortunate since the runtime data we do get is very interesting!

 

[themaxx69]

I'll have to look up how to make a light box and do some medium and low tests.