eneloop vs. Kodak Pre-Charged Voltage Maintenance

UnknownVT

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I have both eneloops and Kodak Pre-Charged LSD in AA size for use in my Pentax K100D dSLR.

This dSLR is well known to be very battery fussy -
Ref: Post #49 (link) in thread - K100D - "Low-Battery" Problem gives details of the meter voltage levels.

The poster measured these voltage levels for the Pentax K100D dSLR -
Battery meter shows full charge at > 1.25v per cell, i.e. >5.00v
Battery meter shows half charge at 1.25v per cell, i.e. 5.00v
Battery meter shows empty and camera shuts down at 1.19v per cell, i.e. 4.76v

On Mar/31 I checked my back-up set of 4x Kodak Pre-Charged AA's - showed full charge when first inserted, but after taking a single test shot - they showed half charge on the camera's meter.

These Kodak Pre-Charged were charged 4 months ago (New Years Eve) - I also charged a set of 4x eneloops at the same time.

In comparison the eneloops were actually in the camera and continued to show full charge level despite having been used more - albeit only occassional ad-hoc shots - but substantially more than the few test shots for checking the Kodak P-C.

Here were my measurements -

Kodak P-C that showed half charge -
#5 - 1.315V, FA=9.0A, 1.301V
#6 - 1.314V, FA=9.0A, 1.309V
#7 - 1.315V, FA=8.5A, 1.300V
#8 - 1.314V, FA=8.8A, 1.304V

these actually look pretty healthy -
and seems they still have a LOT of charge in them.

Contrast with the 4x eneloops which had been used a bit more and were kept in the camera - reading taken Apr/3 after a short photo session -

eneloop - used more, but still shows full charge -
#1 - 1.294V, FA=9.85A, 1.285V
#2 - 1.294V, FA=10.29A, 1.285V
#3 - 1.294V, FA=10.29A, 1.283V
#4 - 1.293V, FA=10.10A, 1.283V

FA= "Flash Amps" - the second Voltages are taken after the FA.

Notice all the open-circuit voltages for the eneloops are lower than the Kodak Pre-Charged - which indicates that these probably are in a lower state of charge than the Kodak P-C.

BUT despite that, the eneloops continue to show full charge on the Pentax dSLR, whereas those Kodak P-C show half charge.

This tells me that the eneloops seem to maintain a higher voltage level Under-Load than the Kodak Pre-Charged.

So it is possible for the Kodak P-C to show empty or even have the camera shut-off when they may still have substantial charge remaining.

This is NOT saying the Kodak Pre-Charge has low capacity, or self-discharges quicker -
in fact the few tests I have seen the Kodak P-C appear to have one of the highest capacities of all LSDs -

But this is a very good illustration of possible higher voltage maintenance of the eneloops over the Kodak Pre-Charged.

Uniross Hybrios are also said to maintain higher voltage levels - the poster in the dSLR thread uses and suggests that -
Chevrofreak claims this too in Post #15 of thread - My Eneloops charge to and hold a higher voltage than other LSD's ... -
he also did some runtimes in a flashlight comparing the Kodak P-C and Hybrio - in posts #13 and #14 in the thread - new Kodac "Pre Charged" NiMH batteries? - which shows that the Kodak P-C have noticably better capacity/runtime in a flashlight over the Uniross Hybrios.

So it appears that the Kodak Pre-Charged do have good capacity -
but the eneloops maintain higher voltage levels -
and this is important for my use in the Pentax K100D dSLR -
since it is battery voltage sensitive.

I think I'll use my Kodak Pre-Charged for flashlights,
and use eneloops for the dSLR.

EDIT to ADD -
Further testing/thoughts -
Kodak Pre-Charged matched eneloops literally step-by-step in unregulated and regulated flashlights see posts #11 and #27 (links)
... and to my chagrin, and pleasent surprise, seem to do as well even in my battery fussy Pentax K100D dSLR see Post #39
(not yet fully proven - but their performance so far have been very good)

Summary of results in Post #57https://www.candlepowerforums.com/posts/2497499&postcount=50
 
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gunga

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Any info on the hybrids? This is pretty interesting since all these LSD cells may be made by only a couple factories.

I wonder if it boils down to the Japanese Sayno/Duracell vs Chinese Hybrid/Kodak etc cells?

Or maybe not, just a theory.
 

Mr Happy

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That's interesting data.

I have made a few spot tests of internal resistance for Eneloops and the Kodak PC cells. I found the Eneloops to measure in the range of 40-50 milliohms, and the Kodaks in the range of 110-120 milliohms. This would be consistent with the Kodaks having a greater voltage depression under load.

Since you mentioned cell voltages I just pulled the Eneloops out of my camera (a Canon A620) and measured them. They are reading 1.27 V and the camera is working fine with no low battery indication.
 

UnknownVT

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I have made a few spot tests of internal resistance for Eneloops and the Kodak PC cells. I found the Eneloops to measure in the range of 40-50 milliohms, and the Kodaks in the range of 110-120 milliohms. This would be consistent with the Kodaks having a greater voltage depression under load.
I just pulled the Eneloops out of my camera (a Canon A620) and measured them. They are reading 1.27 V and the camera is working fine with no low battery indication.

I would tend to agree with you - the lower flash amps readings on the Kodak Pre-Charged would also hint at the higher internal resistance than eneloops.

I have found Canon A-series digicams (I have owned two, and the A610 is my current digicam to take my beamshots) to be very tolerant and frugal with batteries - almost the opposite to the Pentax K100D dSLR which is pretty fussy and voltage sensitive.

So, it is not the open-circuit voltage levels -
since the Kodak Pre-Charged showing half charge in the Pentax K100D dSLR actually had higher o-c Voltages (even after the short but harsh treatment of "Flash Amps") than the eneloops - used significantly more, but still showed full charge.

Here's my version of the battery ends comparison -
KodakPC_eneloopEnds.jpg


and a recent thread of relevance -

[Slightly OT] Cutoff voltage of cameras favors Low Self-Discharge batteries?
 
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eluminator

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100 ohm internal resistance indicates bad NiMH cells when I measure them. Maybe there is something wrong with my measurement technique, but I'm willing to bet those are bad cells and won't work in a high load device like a camera.

I get 30 to 40 ohms with charged good NiMH AA cells.
 
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UnknownVT

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I had to go out to shoot a session yesterday - which I had forgotten about until literally a few minutes before I had to leave the house - so I could not charge up my set of 2500mAh regular NiMH (non LSD).

So I used the set of eneloop that were already in the Pentax K100D dSLR - I took over 50 shots - probably about 2/3-3/4 with flash which is very demanding on the batteries -even after extensive reviewing of the photos - these eneloops are still showing full-charge on the dSLR's indicator.

The readings I got later were -

eneloops -
#1 1.287V, FA=9.60A, 1.280V
#2 1.287V, FA=9.50A, 1.281V
#3 1.287V, FA=10.27A, 1.278V
#4 1.287V, FA=10.18A, 1.277V

All the open-circuit voltages were obviously lower than the ones in the opening post, but the ones taken after the "Flash Amps", although also lower, were still around ~1.28V - open-circuit - these still manage to show full-charge on the Pentax K100D whereas the Kodak Pre-Charged as I reported previously, at above 1.3V o-c started to show half charge.

For those more observant eneloop #4 seems to show a higher Flash Amps than before with more charge.... This is probably due to experimental tolerances - as the Flash Amps are never that precise for me -they do not normally show a steady state - but the numbers fluctuate on my cheapo DMM - I just use a sort of "average".
 
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Mr Happy

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Eneloops are rather good, aren't they?

What you did is what I usually do. Rather than specially charging up a set of cells before using the camera, I just use the Eneloops already in the camera and take a spare set along with. Two sets of Eneloops will last for more pictures than I can possibly take in one outing.

If I bought a DSLR I'd really like one that takes a set of 4 AA cells. They are much more flexible and interchangeable than the built-in lithium battery usually provided.
 

UnknownVT

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Eneloops are rather good, aren't they?

What you did is what I usually do. Rather than specially charging up a set of cells before using the camera, I just use the Eneloops already in the camera and take a spare set along with. Two sets of Eneloops will last for more pictures than I can possibly take in one outing.

Yes, I agree - and I am likely to just use eneloops in the dSLR - with a spare set - like you are doing.

Watching the battery meter yesterday during my shoot, and seeing full-charge all the time, I was beginning to think these eneloops were going to last "forever".

However, I wonder if they might go from showing full charge to depleted/shut-off without much warning, ie: sudden drop-off?

The only thing is that I am now "somewhat" disappointed with the Kodak Pre-Charged - since I have always regarded them as "the same" as eneloops.

In other uses, like flashlights, they do seem every bit as "good" as eneloops, with possibly higher capacity -
but it's in this area of voltage maintenance that they perform less well than eneloops -
and that is precisely the critical area for the Pentax K100D dSLR.

So in terms of voltage maintenance - and specifically for use in the Pentax K100D dSLR the Kodak Pre-Charged are simply not as good as eneloops.

Ref: eneloop actually claims higher voltage maintenance on their Canadian site
 

Mr Happy

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Would these findings hold true for the Duracell pre-charged LSDs (produced in Japan) vs the Duracell pre-charged LSDs (produced in China)?
I don't wish to spend money on any black top Duracell made in China cells to find out.

What I can say is that to the best of my testing ability the Duracell LSDs with the white top, made in Japan, perform the same as Eneloops. The same also goes for the Uniross Hybrios with the white top, although those say they are made in China.
 

UnknownVT

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Here's an ad-hoc experiment to try to highlight voltage maintenance difference between eneloop and Kodak Pre-Charged -
BUT it gave an unexpected result.

I wanted to see discharge in a flashlight that has a relatively high threshold/cut-off voltage.

Background -
I have two Dorcy 45lumen 1AA (41-4253) -
one was a "replacement" (#2) when I thought the first one I had (#1) had an intermittent switch -
in fact it was not a faulty switch - it was the relatively high threshold/cut-off voltage that prevented the light from switching on, when there was still charge in the battery I was using.

For some discussion of this high threshold/cut-off voltage please see Post #37 (link) in
Dorcy 45 lumen 1x AAA Comparison Review

#2 has a marginally higher cut-off voltage than #1 -
about 1.3V vs. 1.27V on batteries measured open-circuit when the light would not turn On. A battery that just would not turn On in #2 can still turn on #1.

So for this ad-hoc test I charged up one eneloop and one Kodak Pre-charged AA let them rest for about 15 minutes and took their readings.

eneloop ... 1.467V; FA=11.2A; 1.447V
Kodak P-C 1.445V; FA=10.6A; 1.429V

eneloop in #2 (slight DISadvantge) and Kodak P-C (slight advantage) in #1- since it has been shown eneloop seem to maintain higher operating voltage than the Kodak P-C.

I took a side-by-side comparison beamshot at the start - then allowing the lights to run for approx 4 mins - switch off for 1 min then took another shot when switched back On - repeated until the lights would no longer switch On again.

Results -
at start 00mins, and after 4mins On and 1 min Off/rest - shot taken when switched back On -
eneKodakPC00min.jpg
eneKodakPC04min.jpg


at ~47mins, and ~51min the last shot before one light would not switch back On.
eneKodakPC47min.jpg
eneKodakPC51min.jpg


after 4 more mins On, then off for 1 min one of the lights would not switch back On -
KodakPC55min.jpg

I was surprised that it was the eneloop that failed to switch back On since I have shown it maintains Higher operating Voltage than the Kodak P-C
Running this for 4 more mins and 1 min Off the Kodak P-C then would not switch back on.... So Total On time = ~59mins

However since I reckoned #2 had a higher threshold/cut-off voltage - I then put the eneloop in #1 (lower threshold/cut-off) - lo-and behold the light came on -
ene55min.jpg

Running this for 4 more mins and 1 min Off the eneloop then would not switch back on in #1 .... So total On time ~59min

Note times given are accumulated On time totals only (the approx 1min Off times were NOT counted).

State of batteries after this test -

eneloop .... 1.179V; FA=2A; 1.046V
Kodak P-C 1.187V; FA=7.5A; 1.143V

The significantly higher Flash Amps of the Kodak P-C tells me there is more charge left in it - whereas the eneloop is pretty close to depleted.

To prove this I put the batteries in turn in a Fenix L1D-Q5 on High (not turbo) and timed how long it would take until No light (~0.9V cut-off)

eneloop ~ 18mins
Kodak P-C ~ 31mins

So the Kodak P-C lasted some 13 mins (72%) longer until depletion in the Fenix L1D-Q5 on High.

Depleted readings -

eneloop ... 0.918V; FA=0.2A; 0.924V
Kodak P-C 0.889V; FA=0.4A; 0.887V

I would say these were fully drained almost on the threshold of being bad for the batteries.

So despite what I first thought was an experiment that gave unexpected results, I can draw these surmises -

In these high threashold/cut-off voltage flashlights there probably isn't any practical difference between eneloop and Kodak Pre-Charged - both will last about 1 hour even if switched off between (note my tests are somewhat "artificial" in running for 4mins On, and 1min Off).

At the point where the Kodak P-C would no longer switch the Dorcy 45lumen 1AA on again, there was more charge left in it than in the eneloop - approx 13 mins more on High in a Fenix L1D-Q5 running until depletion/cut-off in the Fenix.

This shows that the one sample of the Kodak Pre-Charged has significantly higher capacity than the one sample of the eneloop.

BUT in a flashlight with a high threshold/cut-off - this is not delivered as the Kodak P-C cannot maintain a high enough voltage to turn the light back on -
whereas the eneloop can maintain a higher operating voltage so could deliver more of its total capcity.......

This is Not very clear cut -
but I think my surmising/speculating on this is probably right.......
 
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Mr Happy

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I'd say you have the analysis about right.

The test shows how the important measure of capacity is what is actually delivered in a given application rather than the 'total' capacity of a given cell. There are many circumstances in which you can receive less actual capacity from a cell than what the label says.

I also feel that I will steer clear of that Dorcy light. It seems too sensitive to input voltage. If it were running on an alkaline it would only get half the available capacity out of the cell.

Also note that the voltages you measure are changing with time, so it is a bit like trying to hit a moving target. Give it a few hours and those depleted readings of 0.9 V will rebound back up to about 1.2 V.
 

UnknownVT

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I'd say you have the analysis about right.
The test shows how the important measure of capacity is what is actually delivered in a given application rather than the 'total' capacity of a given cell. There are many circumstances in which you can receive less actual capacity from a cell than what the label says.

Many thanks for the affirmation.

However what you say in the second paragraph about delivered capacity - applies to devices with higher voltage cut-off thresholds.

The timed drained tests in the Fenix L1D-Q5 shows that the Kodak P-C can actually deliver noticably more capacity than the eneloop -
when the cut-off threshold is not too high.

These Dorcy 45lumens 1AA lights, as you point out, probably would only partially drain alkalines, and be unable to switch back on when there is still significant capacity left.
Whereas a Fenix L1D probably would be able to utilize the battery's capacity better.
 

Mr Happy

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However what you say in the second paragraph about delivered capacity - applies to devices with higher voltage cut-off thresholds.
The voltage threshold is not the only factor though. The discharge current, the way the cell is charged, the time since charging and the ambient temperature are all factors that can affect how much capacity you actually see when discharging a cell.
 

UnknownVT

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The voltage threshold is not the only factor though. The discharge current, the way the cell is charged, the time since charging and the ambient temperature are all factors that can affect how much capacity you actually see when discharging a cell.

Got you. Of course I accede to your better knowledge, and more complete answer.

I meant in this ad-hoc experiment above - it was the higher voltage cut-off threshold that was the main determining factor that had the eneloop and Kodak P-C showing neck-and-neck in terms of usable capacity in the those Dorcy 45lumen 1AA light(s).

However it would seem that the Kodak P-C will show a noticable higher usable capacity in a light that has a lower (more sensible) voltage cut-off threshold such as the Fenix L1D-Q5.
 

Power Me Up

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Could it also be that the Dorcy isn't fully regulated and so actually draws more current from the Eneloop (because of the higher voltage) causing it to run out sooner?

It might be interesting to compare the run times for the Eneloop and the Kodak in the L1D after they're both fully charged. If the Eneloop maintains a higher voltage, the L1D should draw a lower current from the Eneloop due to the fact that the L1D is fully regulated and could quite likely run longer with the Eneloop even though it has a lower measured capacity.
 

mdocod

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Of all the NIMH AA cells I have owned, the eneloops are the only cells I can really rely on to take the abuse of my lack-of-care methods. I don't match cells in sets for use in adapters, I don't do break in cycles, I don't keep track of anything, I just have a bin of charged and used cells and run through em. Sometimes slapping cells in a pack and pack charging them, sometimes using them in single cell lights, sometimes grabbing a few to snap a few shots in the Camera. They have proven to be the ONLY NIMH cells that will reliably run my Camera without showing pre-mature low-battery indicators. I have overheated some of these (to the point of melting the wrapper off), left some out in the car on nights below 0 degrees F. charged at rates as high as 6.5A... They just keep on going without much if any negative issues. The eneloop cell is amazing for so many reasons. IMO, it represents the ideal behavior and tolerance of a rechargeable consumer cell. With the right marketing and consumer awareness, cells like these could completely replace most other types of cells on the market.

Eric
 

SilverFox

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Hello Eric,

:devil: I must warn you that your cruel and torturous treatment of this limited species of cells will not go on without an outcry from seasoned batteryoholics...

I think your behavior should be turned into "Battery Protective Services" as it seems you are unable to provide a suitable environment for the long life and optimum performance of the cells in your care.

Fortunately, the Eneloop cells are robust, but even they have their limits.

Consider this a warning that I will offer no sympathies IF your cells every die. :devil: :) :) :)

Now, I have to get back to my 15 minute charge testing of these cells... :)

Tom
 

UnknownVT

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It might be interesting to compare the run times for the Eneloop and the Kodak in the L1D after they're both fully charged. If the Eneloop maintains a higher voltage, the L1D should draw a lower current from the Eneloop due to the fact that the L1D is fully regulated and could quite likely run longer with the Eneloop even though it has a lower measured capacity.

This is in fact Sanyo's claim for eneloops - on their Canadian site -

" Higher Operating Voltage
Higher voltage means that Eneloop 2000 mAh batteries will have similar performance to 2500mAh conventional rechargeables. "

In the Dorcy 45lumen 1AA with the UNreasonably High cut-off threshold voltage - the 2000mAh eneloop appears to have the same/similar runtime/capacity as a 2100mAh Kodak Pre-Charged ........

BUT the remaining capacity used in a more reasonably set cut-off voltage of ~0.9V in the Fenix L1D-Q5 showed that the Kodak Pre-Charged had 13mins (72%) more runtime to no light (cut-off) than the eneloop.

So in my example because of the UNsuitably high cut-off voltage the eneloop does show itself to be as good as at least a 2100mAh LSD......

However if they were put in a lower or more suitable cut-off voltage device/light - the Kodak P-C probably would show better/longer runtime -
see Chevrofreak's runtime of the Kodak P-C vs. Uniross Hybrio -
in posts #13 and #14 in the thread - new Kodac "Pre Charged" NiMH batteries?
- which shows that the Kodak P-C had noticably better capacity/runtime in a flashlight over the Uniross Hybrios.
 

Black Rose

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I'd like to try some of the Kodak Pre-charged cells, but cannot find them here at affordable prices like they are in the US.

Wal-mart up here does not carry them at all, and the only local store I found them at wants $20 for a pack of 4 AAs :faint:
 
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