CR2016 vs CR2025, battery experts?

Can I assume that if a CR2016 is rated at 80mAh and a CR2025 at 170mAh that when connected to say a Nichia 5600 LED that the 2025 will last double the time than the with the 2016? (Of course I would be using 2 of each to get 6v).
Are there no internal resistance considerations between the two?
I am sure the drop off curve would have the same shape for both just that the one for the 2025 will be strecthed over a longer time period.
What I am ultimately asking is that if I ran my keychain light on 2x2025 instead of 2x2016's firstly would it run as bright and secondly would it run for longer?
Your comments please.

It would run brighter pretty much the whole time and it would run longer. I would doubt it would run 2x as long, probably more like 1.5 times longer since it would be brighter (using more power). You also are pushing the LED harder and it won't last as long. I couldn't even guess how much shorter, although I wouldn't worry about it.

A good question. Here's something to chew on:

The Photon 2 uses 2 2016's with no resistor. Run time stated by the mfgr is 12-14 hours.

The PocketBright uses 2 2025's with a small resistor. Runtime stated by the mfgr is 50 hours, BUT...

I'm doing a runtime test on the PocketBright by request. I can't watch the thing very often, so no curves or graphs or anything, but here's what Ive got:

Start: 12 Lux

10 hours on (I work full time): Bouncing between 2 and 1 lux - majority of the "bright light" power from the batteries has been discharged

14 hours on (a bit before bedtime): steady at 1 lux

24 hours on (next morning): <1 lux on the meter (reads "0"), but still lit and "usable" in the dark.

So, even with the higher capacity batteries, your runtime until the low end of the discharge curve (almost flat discharge around 1 to 0 lux) is still 12-14 hours.

Next I'll probably do the same to a photon and an infinity.

Thanks Brock, Quickbeam.
Quickbeam, this is what I was worried about without some kind of current limiting. Space has been compromised (2025's are thicker) but there is no appreciable increase in run time.
What I dont understand then is why is the capacity of the 2025 more than double that of the 2016 yet the results prove different? Unless of course the Phtotn test will infact show 7 or 8 hours continuous and not the advertised 14 hours. Also, I would imagine that these coin cells are not designed to run a 30mA, If run at there designed current draw the 2025 would probably produce the goods over the 2016.
We await your Photon test with baited breath!!
I am currently playing with 2 white LED's in parallel running off three NiMh AA cells via a programmable PWM circuit (100%, 75%, 50%, flashing), Problem is the PWM has an auto off on all the modes excpet 100% so cant leave it on those modes for extended periods to test battery life but should be ages.

A 2016 cell is 20mm in diameter, and 1.6mm thick. A 2025 is 20 x 2.5mm, it has a higher internal volume, and so the better rating. However, these are cells designed to deliver very low currents for very low durations. They have very low internal leakage, (great shelf life) but the voltage collapses pretty quickly under high current loads. They are designed for memory backup, large watches, things like that.

This would explain why they do so well at the end of the discharge curve. The draw is low, so they last a long time.

End result: Lightwave Pocket-bright, 2x2025 cells: 50 hours, 0 lux at one meter... ...but wait! At 1 foot, the light is putting out 6 lumens per square meter. Good enough to read in the dark, so the Lightwave claims are validated - "usable light" acording to them is still being able to read a newspaper by the light in the dark, and you can do that.

It's very dim, but in complete darkness it's enough to negotiate a dark house.

Now for the photon test. Same deal. I work all day so I'll put in new 2016 batteries, set up in a closet, let it go, and check back every 10-14 hours to see how it's doing. What I'm most concerned with is the final output. Per mfgr's listings, the photon is good for 12 hours. Let's find out how it compares.

Thanks for the effort Quickbeam. I have sold many Photons and when asked I always say battery's last 14 hours continuos as the manufacturer claims. It is very unlikely that anyone would levae the unit on for 14 hrs so it would be better to rate these units at a particular duty cycle which more closley resembles day to day use.
Given this duty cycle I am sure one would find that the 2025's would come into their own over the 2016's.
Looking forward to your results.

OK. Photon results so far.

Start, new batts. 21 (!) lux at 1 meter
15 min: 17 lux
25 min: 13 lux
100 min: 5 lux
150 min: 4 lux
240 min: 3 lux
(went to bed)
720 min (12 hrs): 0 lux at 1 meter, 13 lux at 1 foot
840 min (14 hrs): 12 lux at 1 foot

If you put the numbers in a graphing program, you should be able to get a "best fit" plot of the discharge.

so, the 2025's did put out more energy - at 14 hours the pocketbright was still at 1 lux at 1 meter, where the photon was less than 1. They are both at the bottom leg of the discharge curve after 14 hours, having dropped from much higher brightness levels.

It appears that using the 2025's only really help a little on the high end, but help a lot on the low end of the discharge curve.

Of course this doesn't represent "real life" testing. For that we would probably need 30 sec on, 5 min off cycles or something like that for the life of the batteries.

Thanks for the trouble Doug.

Re: CR2016 vs CR2025, will 2025 fit into 2016 slot

Reviving an old post!

So, has anyone ever fit 2 CR2025's in any coin cell LED light (like the Inova Microlight, or Photon etc) that are designed to hold 2 CR2016?

Re: CR2016 vs CR2025, will 2025 fit into 2016 slot

[ QUOTE ]
BuddTX said:
Reviving an old post!

So, has anyone ever fit 2 CR2025's in any coin cell LED light (like the Inova Microlight, or Photon etc) that are designed to hold 2 CR2016?

[/ QUOTE ]
Yeah, and in the majority of cases, they just won't fit. /ubbthreads/images/graemlins/frown.gif

-Woulda been great..-because of the doubling of amp hour capacity, though..

Re: CR2016 vs CR2025, will 2025 fit into 2016 slot

Actually, I prefer to run a SINGLE CR2025 in my white Photon - @ 3v, the output is of course less (maybe about 30% of the normal, twin CR2016 output - by eyeball...), but it still provides plenty of useable light (in a pinch) at a flatter, longer lasting rate.

Bob

Re: CR2016 vs CR2025, will 2025 fit into 2016 slot

You should be able to fit a 2032 in there, since that's what the warmer colors (lower voltage leds) run on.

Re: CR2016 vs CR2025, will 2025 fit into 2016 slot

Dang! paulr, you know what I did better than I know what I did! Just cracked open my Photon, and sure 'nuff I had put a 2032 in there - not a 2025 like I thought... /ubbthreads/images/graemlins/blush.gif

Bob... /ubbthreads/images/graemlins/twakfl.gif

Re: CR2016 vs CR2025, will 2025 fit into 2016 slot

No prob. Done any runtime test with the 2032? My concern is that you get 30% output with a new 2032, but as soon as there's some voltage sag you might get just 1% output.

Re: CR2016 vs CR2025, will 2025 fit into 2016 slot

Put two 2016's into the Photons that were intended to use one 2032. You'll lose runtime, but you'll gain brightness. LED life suffers from that though.

Re: CR2016 vs CR2025, will 2025 fit into 2016 slot

No runtime test, but a year of regular intermittent use seems to have made very little, if any, difference in output. But a year is a long time to "remember", and now I'm curious.

I recently aquired another old beat up, unused Photon white from a friend - I'll get a fresh set of 2032's and do an eyeball runtime comparison in the next few days, and compare the 50% output appearance to Quickbeam's 2016 results above (looks like about 30-40 minutes there). Non-linearities between eyeballs and light meters withstanding.

Bob