AA bats 3.7 v Lithium versus 1.5 v Alkalines LUMEN OUTPUT?

QUESTION: Concerning AA batteries at 3.7 volts Lithium versus 1.5 volt Alkaline Batteries and Light Output?


Took delivery on my DQG AA XP-G2 "R5 3B NW" today.


http://www.fancyflashlights.com/goods.php?id=424


This is my first AA LED that can handle "14500 lithium bats". I was hoping to see higher output using a 3.7 volt battery versus a 1.5 volt battery, but maybe it's my misunderstanding how some of these LED lights actually work depending on the electronics in the head unit.


In anticipation, I decided to stick with the well known brand "AW", and bought 2 "AW IR P14500P - Protected AA - 750 mAh" black labeled batteries, that charge fine on my Pila charger.


This particular light is listed as "Current Regulation", so far testing with a photo light meter (all I have to test lumen output), I am noticing very little actual increased output, from the 3.7 volt lithiums, to a standard 1.5 volt energizer or new, stock "Energizer Ultimate Lithium" which usually start off at 1.7 volts. My Eneloop 1.2 Volt AA's, do show a bit less light output. My simple light meter tests, show approx. ONLY a 1/3 exposure increase from the 3.7 v. lithium from the 1.5 v. AA alkaline.


The LED head does get VERY HOT with the 3.7 volt battery on high for more then a few minutes. Just using my hand for heat measurements, it does get hot with a 1.5 volt alkaline, but not as fast, but perhaps just as hot in while running (hot in this case is feeling almost too much heat to continue holding on, when squeezing the LED head with two fingers). This is not my major concern, light output was the goal, but if there is little difference in that aspect, not sure what the advantage is for using 3.7 volt Lithiums is now, unless one can simply get longer run times over a AA Lithium Energizer and of course the ability to recharge them?


Wondering if this is "normal" behavior, and if so, does this mean the lights "current regulation", steps down the voltage? I have read many times here that putting in 3.7 volt AA lithiums really increases the lumens output in most lights that can handle them, but that is based on comments on many various AA LED light brand topics here, and may not be related to the design of this light.


Confused?

The light's driver is regulating the output. Current draw on a 14500 is about .6A on high, and about triple that with a lithium or NiMH AA. Alkaline has a hard time giving up 2 amps.

bdiddle said:

The light's driver is regulating the output. Current draw on a 14500 is about .6A on high, and about triple that with a lithium or NiMH AA. Alkaline has a hard time giving up 2 amps.

Click to expand...

So in simple terms, I'm NOT going to see much difference in brightness between AA batteries in this flashlight, just longer run times with the 14500, correct?

mactavish said:

So in simple terms, I'm NOT going to see much difference in brightness between AA batteries in this flashlight, just longer run times with the 14500, correct?

Click to expand...

It depends on the light....for the ones where they don't actually specify if it can take rechargeables...its a crap shoot.

Sometimes, they fry, sometimes they are brighter but have reduced run times, etc.

It comes down to the LED and drivers it has, etc.

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If its meant to take EITHER, the regulation will typically do some combination of brighter and/or more runtime.

Most of the ones I have that are meant to take either are brighter and run longer on the rechargeables.


After that, the drivers etc, control HOW MUCH brighter, or longer, they run.

As YOUR light specifies the SPECS based on a 14500, you can assume its performance is optimized with one, but that it CAN take the primaries with a cost in performance.

Thanks TEEJ, I aware of the first part of your post, but realize I still have a lot to learn about the drivers and what they really do. I simply wanted to try getting "bonus" lumens, or close to the high output lumens I've seen on some AA LED reviews, since I already have a good Lithium bat charger (pila), and it was cheap enough to buy 2 AA AW IR 14500P's. My EDC is the DQG AAA version which I love for it's size and output.

I've been following the thread on the AA OLight S15, which must use an entirely different approach in their driver, as the lumens are dramatically increased when moving from a standard AA to a Lithium rechareable AA (good "output VS runtime" chart there). Same as the soon to come out MBI Torpedo in the custom thread but in the AAA format. Until I learn more, I'll assume that in my case, in the AA DQG, any good AA battery will give close to max output until it drops off, while the 4.7 volt rechargeable Lithium AA will simply deliver the same current, but for a longer time period.

This is what you want. Get a quark 2AA turbo light and order the single AA body and put in that 14500 and you'll have the bonus lumens output you're looking for!

Thanks, I think I get it now, went back and read some of the lights I was interested in. Seems some have current regulation for Nimh bats, and primaries, but when a Lithium rechargeable is put in, it becomes what some members term "direct drive", the LED getting all the voltage, hence the much higher outputs, at the expense of course of less run time, and possible overheating. Most of these, folks publish warnings about running them for just a short time on high. Some even have CR for lower settings and then none for the highest setting, with a Lithium, guess it's just a matter of reading the reviews here, as little of this info seems to get published on the sales and manufacturers sites, for safety and legal reasons I assume. I even noted that depending on the light and controller, some of these lights lose lower lumen settings when pushed with a Lithium, or the spacing between hi/med/low, can be altered as well.

I have a few good AA lights already, and this DQG is certainly a nice keeper, and bright, and I guess in most cases it's both good and smart that the voltage is regulated. I played around with it, not continuously but overall I probably got the 60 minutes of high runtime on my AW IR 750 protected Lithium, before this light started "blinking", which is NICE it has a low battery voltage warning. The blinking happened twice quickly and then the light quit. Since I could not get any voltage reading off the battery, I assume the battery's protection circuit kicked in, good to know it works right, and had NO problem, charging it back up in the Pila charger.

What I am looking for, and there seems like a decent amount of choices in AA lights, is one that touts being able to handle 3.7 volt lithiums, but can deliver the largest lumen output at high, not being held back or throttled by a regulator. Just interested in seeing how bright a AA LED can really be.

Here is one example, the XENO EO3 V3, from the link review below: "The E03 appears to be current-controlled on its low modes", and "On 14500, the E03 is a real barn-burner on Hi".

http://www.candlepowerforums.com/vb...-G-R5-Neutral-White-Review-RUNTIMES-BEAMSHOTS