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10-23-2008, 12:43 PM   #46
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QuoteOriginally posted by bjsmith Quote
When the batteries are unable to output the current required, the voltage drops.
Thank you for your very detailed reply.

This is true, all batteries behave like this - strictly speaking one should be talking about the ability to deliver total power in watts.

However having agreed with that, the Pentax K100D still has a too high voltage threshold cutoff -
you gave the example where batteries still had plenty of capacity - but would not power the camera adequately

QuoteOriginally posted by bjsmith Quote
In other words, it starts dropping towards 1A "real-time" current, which then pushes the voltage down below 1.2V, when only 1/3rd to 2/5ths of the actual charge is depleted.
- I have experienced this myself with the otherwise excellent Kodak Pre-Charged LSD NiMH rechargeables where it was very obvious that the batteries had plenty of remaining charge - but the K100D was not able to utilize it - in fact shutting down prematurely (a mere turning off and back on was enough to revive/resusitate the batteries to continue shooting)

QuoteOriginally posted by bjsmith Quote
That's why I said I can get 500+ shots out of NiMH in AF.S when doing infrequent scenery shots over a day, but I can't get even 300-400 when in AF.C at a sporting event over 1-1.5 hours (a good 40 minutes shooting). And the batteries will eventually discharge on their own, even if Eneloops are slower at that, it still happens. At the same time, I can easily get 1000+ shots out of LiFe in AF.C over two (2) different, 3+ sporting events.
Eneloops do behave quite a bit better than Energizer 2500mAh NiMH.

You are lucky as Energizer 2500mAh NiMH have a very bad rep over at CPF's Flashlight Electronics - Batteries Included section with frequent reports of them not holding charge - some as low as only a few days.....
this seems to apply to other higher capacity (>=2500mAH) NiMH - even the best known brands - as the separators are thinner to be able to pack in more chemicals/capacity - so tend to be more fragile and prone to damage -

ref:
More dying Energizer 2500's...

Duracell 2650 batteries dying


eneloop vs. Energizer 2500mAh NiMH -

In the thread NiMh Battery Shoot Out

there are graphs of both the Energizer 2500mAh NiMH and eneloop under various current load/draws.

Using the 2 Amp load -
Energizer 2500mAh would dip below 1.19V (K100D's threshold cutoff = 4x 1.19V) at only about 0.4 Amp-hour - which is only about 18% the capacity if the threshold cutoff was to a more practical/realistic 1.0V.

eneloops at the same 2.0 Amp load/draw manages to stay above the threshold 1.19V - up to about 1.4 Amp-hours - which is almost 4x "better" longer than the Energizer 2500mAh NiMH. This is delivering abut 78% of its capacity if the threshold cutoff was to the more realistic 1 volt (=1.8A-hrs)

I recommend eneloops since I have proven they manage to maintain high enough voltage under-load for the K100D to work even when the batteries were charged some 4 months previously.

Of course caveat - I do not shoot AF.C so may not see some of the other problems using that mode -
but eneloops work really well for my usage.


Last edited by UnknownVT; 10-30-2008 at 12:59 AM. Reason: typos; corrected figures
10-29-2008, 06:50 PM   #47
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QuoteOriginally posted by UnknownVT Quote
This is true, all batteries behave like this - strictly speaking one should be talking about the ability to deliver total power in watts.

However having agreed with that, the Pentax K100D still has a too high voltage threshold cutoff - you gave the example where batteries still had plenty of capacity - but would not power the camera adequately
Then using your own term, it's not the Pentax K100D, but the inadequate, electric power (wattage) delivered by the batteries overall. The Pentax has electric potential (voltage) cut-off to prevent a brownout.

Understand electric power (wattage) always stays consistent, even as inadequate electric current (amperage) causes electric potential (voltage) to drop. The derived, algebraic ideal** of this direct, electric current (DC) system is P = IV. P will remain constant, even if P is inadequate, due to P being inadequate. Assuming, of course, V is the actual, nominal potential of the device utilizing the battery circuit and providing the load on it.

**NOTE: I stress "algebraic ideal" because systems are hardly such. But there's no need to start deriving a full system of equations with more factors, inefficiencies and aspects that explain their interactions (at least in common battery designs and microelectroics+motor loads), and even my calculus is rusty on these matters (and it's been years since I designed such)

QuoteOriginally posted by UnknownVT Quote
- I have experienced this myself with the otherwise excellent Kodak Pre-Charged LSD NiMH rechargeables where it was very obvious that the batteries had plenty of remaining charge - but the K100D was not able to utilize it - in fact shutting down prematurely
Correct, because the electric current (amperage) was inadequate, causing the electric potential (voltage) to drop. It only takes one battery with inadequate current in a series battery circuit to cause the potential of the circuit to drop.

In a series battery circuit, potential (voltage) is sum, current (amperage) is median. If the current (amperage) coming from one batter is unable to maintain the median, then it will drop potential (voltage) to compensate. That in turn causes overall potential (voltage), which is sum, to drop. In any case, the power (wattage) is, essentially, constant.

You can't "create" current (amperage) out of "thin air," either the battery is supplying adequate or not at its potential. If the current (amperage) is inadequate, then the power (wattage) is in adequate. When the potential (voltage) drops to increase current (amperage) to the media, the overall power (wattage) still remains the same in the circuit.

Again, it only takes on battery in that series circuit to cause the problem. As potential drops, the Pentax potential (voltage) regulation kicks in to prevent a brownout due to a potential it is not rated to receive current at. That prevents both microelectronics, although a lot of microelectronics are semi-conductors and have their diodes (which cut off as well, or fail to switch or indicate a change of or specific state, although that's a mega-oversimplification), and more importantly, simple motors, which are at greater risk. It's basically the opposite risk of over-potential (over-voltage causes transconductance, which is very bad for integrated circuits and other semiconductors).

QuoteOriginally posted by UnknownVT Quote
(a mere turning off and back on was enough to revive/resusitate the batteries to continue shooting)
That's because you're putting the device back into a transient. The initial, open potential (voltage) goes back to the pre-current (amperage), aka load. "Voltage" is literally only the "potential" to do electrical power (wattage) -- essentially "work." The actual, electrical current (amperage) is that measure of the flow against that potential. Hence the phrase, "it's not the volts that kill you, but the amps."

When the load and resulting current (amperage) is re-applied, the potential (voltage) will eventually drop again. Inadequate current has its fluctuations, and may take some time for the initial transient to "shake itself out" and normalize. That's all you're seeing there. Consumer nickel compounds actually drops its ability to provide consistent current (amperage) as it discharges, whereas consumer Lithium compounds do not, so the more you do this, the less it will work (and more likely cause temporary issues, possibly permanent eventually if the K100D doesn't cut-out high enough).

If I try to throw an Energizer e2 Photo Lithium at a 3A device problem, then it's 2.6A capable battery, and it likely won't even show as much "effort," it just likely cut out immediately (if I'm lucky -- I don't like to "tempt fate" with Lithium). Of course, device designers are likely to increase the electric potential (more batteries in series) to reduce the current required to solve that problem. Hence why you have 2x AA devices, 4x AA devices, as well as 2 cell Li-Ion devices (7.2V), 4 cell Li-Ion devices (14.4V), etc... Again, P = IV.

The root cause is that at least one of your batteries is providing inadequate current (amperage), which means it has inadequate power (wattage) and that will cause the potential (voltage) to drop. The potential (voltage) "cut-off" is actually a protection mechanism. It takes advantage of the natural relationship between electric current and electric potential, and recognizes when the current is greater than actually provided if the potential required, with the potential correspondingly dropping, and naturally cuts off all potential because inadequate potential is just as bad as too much.

The result is that the camera shuts itself off. Why? Again, your batteries are incapable of providing the [real-time] current required, regardless of the [charged] current-time they may be capable of. The value of current-time has nothing to do with the value of current. In fact, current-time varies wildly based on actual current draw.

Last edited by bjsmith; 10-29-2008 at 07:07 PM.
10-29-2008, 07:48 PM   #48
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QuoteOriginally posted by Romoman Quote
I'm using Sanyo 2500 mAh Ni-MH. They seem to last around 700 pics and charge in only 15 minutes. I've had them about a month and they seem awesome.
what charger are you using?
10-29-2008, 10:07 PM   #49
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I also used Energizer NIMH 2500 mah batteries with success. Now I use a Travor battery grip. It is great and I have only charged it once in the last two months. No battery worries.

Dave

QuoteOriginally posted by cznut Quote
What has worked out best for you guys?
Need something that lasts long yet economical


10-29-2008, 10:28 PM   #50
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QuoteOriginally posted by Big Dave Quote
I also used Energizer NIMH 2500 mah batteries with success. Now I use a Travor battery grip. It is great and I have only charged it once in the last two months. No battery worries.
Dave
There are two different types of battery grips out there.

One uses multiple sets of AA, which makes NiMH very usable. Why? Because it not only puts AAs in series (sum voltage, median current), but it puts sets of AAs in parallel (median voltage, sum current). That means you are now summing the current between sets of AAs, so you can now easily get 2A+ out of your NiMH batteries, because you're adding the current between sets of 4x NiMH in parallel. Heck, they could even use sets of 5x NiMH and get 6V nominal (and even if they are over-charged to 1.3V, it would be 6.5V and within tolerances), although they probably would not normally (as people might mistakenly put 5x Alkaline or Energizer Lithium which would be 7.5V nominal).

The other uses a Li-Ion combination that does actually result in a real 6V. It's much easier to do as it is above 3.6V and you have plenty of space outside the unit, like in an external batter pack. I'm curious to find out if they are using 2 x 3.6V packs and transforming down to 6V, possibly even more packs / higher voltage and transforming down to 6V, or if they are using a proprietary, rechargeable Lithium chemistry that is actually 6V nominal (which is possible).
10-30-2008, 12:50 AM   #51
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I went through the wedding I talked about earlier and I had more than 1000 photos taken during the afternoon and evening. I'm very happy with the grip as it makes holding the camera much easier now and it improves the focusing speed a LOT. I was focusing pretty fast in dimly lit areas where my camera wouldn't focus at all had I been using AAs.

I just brought my Lacrosse bc700 with me and as I was shooting a set of eneloops was being charged and so on. I might have charged the batteries like 4 or 5 times.

The travor grip is very, very recommended.
10-30-2008, 12:54 AM   #52
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QuoteOriginally posted by bjsmith Quote
Then using your own term, it's not the Pentax K100D, but the inadequate, electric power (wattage) delivered by the batteries overall. The Pentax has electric potential (voltage) cut-off to prevent a brownout.

Understand electric power (wattage) always stays consistent, even as inadequate electric current (amperage) causes electric potential (voltage) to drop. The derived, algebraic ideal** of this direct, electric current (DC) system is P = IV. P will remain constant, even if P is inadequate, due to P being inadequate. Assuming, of course, V is the actual, nominal potential of the device utilizing the battery circuit and providing the load on it.
I think we may be describing the same thing - but doing it in different ways.

I am borrowing SilverFox's excellent discharge graph of the Energizer 2500mAh NiMH


If we look first at the 2Amp discharge curve (dark green) we can see that after about 0.4Amp-hours (on the horizontal axis) the curve has dropped to abut 1.19V - the cut-off voltage of the Pentax K100D -

So if the K100D drew 2Amp constant current (which it doesn't) - then at 0.4Amp-hours which would be about 0.2 hours or 12 minutes the K100D would shutdown because the batteries would not be able to deliver enough current at the required voltage - or saying the same thing another way for the required current of 2Amps the batteries are no longer able to maintain a voltage above 1.19V - both are saying the same thing - but to be strict - it is the battery unable to deliver the required power - watts...... you say tomato.....

Now look at the 1Amp curve (mauve/burgundy) it manages to stay above 1.19V until about 1.6Amp-hours - at 1Amp this would be about 1.6hours.

So at a lower 1Amp draw the batteries would last about 1.6hours (if it was contant current - again this is not really the case - but just a mere example) -

At the lower current of 1Amp one can see the K100D could utilize more of the battery's charge of about 1.6Ah out of a tested total 2.230Ah - whereas at 2Amps only about 0.4Ah is utilized out of the tested total of 2.236Ah.

Now let's look at the eneloop - discharge graph again borrowed from SilverFox -


Using the same 2Amp draw curve (dark green) one sees for the eneloop - the curve does not dip to 1.19V until about 1.4Ah.
And for 1Amp (mauve/burgundy) the curve stays above 1.19V until about 1.7Ah.

So the eneloop manages 1.4Ah out of a tested total of 1.807Ah at 2Amps,
and 1.7Ah out of a tested total of 1.871Ah at 1Amp......

The respective total energy tested were -

Energizer 2500mAh NiMH
2.555Wh at 2Amps
2.674Wh at 1Amp

Eneloop
2.158Wh at 2Amps
2.320Wh at 1Amp

clearly the Energizer 2500mAh NiMH hold more charge/energy than the eneloop -

Yet the eneloop would be able to deliver more of its charge/energy than the Energizer

I don't know how else to describe this difference other than the eneloops manage to maintain a higher operating voltage under the same load than the Energizer 2500mAh NiMH.

Last edited by UnknownVT; 10-30-2008 at 08:51 AM. Reason: typos
10-30-2008, 01:00 AM   #53
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QuoteOriginally posted by Class A Quote
In what way do you think 4 x 1.2 V (from NiMH) are too little? After all the K100D is sanctioned to use this type of battery. Is it just the AF performance that suffers a little? I don't shoot action and the AF performance with my 4 2500mAh Energizers seems just fine.
I discovered this myself a couple of weeks ago - I had a set of Li AAs (Energizer e2 Ultimate) lying around, and decided to throw them in my K100. I was pretty shocked to discover that autofocus was noticably faster, especially under the so called 'hunting' conditions(it was still seeking, but it was doing so faster).

I had previously been using Energizer NiMH AAs, and I'll be rethinking that decision now.

QuoteOriginally posted by bjsmith Quote
Lots of informative things
Thank you very much for this informatative series of posts - it's been very interesting to read!

Also, I have a point which may corroborate what you've been saying, but from a different angle. Ever noticed how a K100 feels slightly off-balanced with NiMH rechargables? Try it with Li AAs or CR-V3s. They're lighter than NiMH batteries and the camera feels much more balanced.

To my mind, this suggests we maybe weren't really intended to use NiMH rechargables in the first place...

10-30-2008, 11:53 AM   #54
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QuoteOriginally posted by cpopham Quote
I discovered this myself a couple of weeks ago - I had a set of Li AAs (Energizer e2 Ultimate) lying around, and decided to throw them in my K100. I was pretty shocked to discover that autofocus was noticably faster, especially under the so called 'hunting' conditions(it was still seeking, but it was doing so faster).
I had previously been using Energizer NiMH AAs, and I'll be rethinking that decision now.
Thank you very much for this informatative series of posts - it's been very interesting to read!
The sensitive microelectronics and ICs are why 4.8-6V is nominal, and 6.5V is absolute maximum. The AF motors will be far, far more tolerant over over 6V, as well as far less "peppy" the more if you don't close in on 6V.

You should strive to provide the Pentax K100D both ...
A. 6V -- either 4 x 1.5V Li-Fe AA or 2 x 3.0V Li-Mn CR-V3
B. 2A

Comparison of Energizer products ...

Energizer L91 (e2 Photo Lithium), Li-Fe:
http://data.energizer.com/PDFs/l91.pdf

Energizer NH15-2500 (Rechargeable 2500), NiMh:
http://data.energizer.com/PDFs/nh15-2500.pdf

The L91 datasheet shows how actual current draw causes a great reduction in lifespan (if usable at all) of Alkaline. I.e., you aren't going to get the same "total mAh rating" if you're pulling a lot of current, you won't see all of it in the end. It also shows how well it takes 1.5-2A+ at 1.5V dropping down to 1.2V before it finally cuts out.

The NH15-2500 also does a good job of showing its output. It maintains 1.2V but eventually it drops. If you throw too much current on it, it doesn't even provide 1.1V. Remember, the total current-hours "charge" can vary greatly on real-time current in the discharge, and drastically reduce the actual power-hours (mWh) you get in the end.

The L91 pretty much always puts out 3-4Wh total. The NH15-2500 has trouble providing more than 3Wh total, and that can quickly drop. Alkaline might be good for 2Wh total, but if you throw just a 1A load on it (which NiMH can handle and LiFe rules at ), you won't even get 0.2Wh.

QuoteOriginally posted by cpopham Quote
Also, I have a point which may corroborate what you've been saying, but from a different angle. Ever noticed how a K100 feels slightly off-balanced with NiMH rechargables? Try it with Li AAs or CR-V3s. They're lighter than NiMH batteries and the camera feels much more balanced.
Lithium is noticeably lighter than nearly all other metalic battery chemistries (with few exceptions, although at least among commodity technologies).
QuoteOriginally posted by cpopham Quote
To my mind, this suggests we maybe weren't really intended to use NiMH rechargables in the first place...
Again, I can go to Costco/Sam's club and, for $19, get a twelve (12) pack of Energizer L91 (LiFe) batteries. That's three (3) sets of four (4) batteries.

Each set will give me about 1,000 shots in either AF.C (sports) or 1,000 shots in AF.S with nominal flash here and there (various usage), at a minimum. And I can keep the batteries in there all I want, don't have to worry about discharge (unlike NiMH, or even the regulation logic in any Li-Ion that eats its own power). They're "ready-to-go." The AF is snappy throughout nearly all of its life, and when the current finally drops, the battery is almost totally discharged anyway.

At 1,000 for $6.33/set, that's $0.00633 per shot, a solid 1,000 shots at that (near full power). So if I take 20,000 shots per year (which is already hitting the camera pretty good, that's an average of almost 400/week), that costs me around $125/year. If I'm more conservative with my AF.C and flash use in AF.S, I can stretch it to 1,500 shots/set, and bring the costs down well under $100/year. If I only shoot 100/week on average, instead of 400/week, then we're talking under $25-30.

It's worth my time and energy to just buy the L91s.

Last edited by bjsmith; 10-30-2008 at 12:00 PM.
10-30-2008, 12:14 PM   #55
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QuoteOriginally posted by UnknownVT Quote
clearly the Energizer 2500mAh NiMH hold more charge/energy than the eneloop
Charge in current-time (Ah) under a low [real-time] current discharge.

QuoteOriginally posted by UnknownVT Quote
Yet the eneloop would be able to deliver more of its charge/energy than the Energizer
Charge in current-time (Ah) under a higher [real-time] current discharge.

Over time, the amount of "charge" in current-time (Ah) or total "work" in power-time (Wh) is not constant but linearly dependent on the actual [real-time] current draw.

Only [real-time] power (W) remains constant, as a product of [real-time] current (A) * potential (V). I.e., when current (A) is inadequate, potential (V) drops to increase current, but power (W) remains the same. P = IV (power = current * potential).

But the current-time (Ah) and power-time (Wh) may be reduced as a result of increased current (A) / power (W) discharge in real-time.

QuoteOriginally posted by UnknownVT Quote
I don't know how else to describe this difference other than the eneloops manage to maintain a higher operating voltage under the same load than the Energizer 2500mAh NiMH.
That's the "effect," not the "cause."

The "cause" is that the Eneloops here are capable of more electric current than the Energizers, enough to meet the flow and discharge of the K100D.

When devices require more current (A) than what the battery is capable of providing, then potential (V) drops to increase the current (A). The [real-time] power (W) still remains the same. So the Eneloops are clearly capable of more [real-time] power, regardless of what the actual, total current-time (Ah) or power-time (Wh) the battery is capable of.

It's all about current (A), not potential (V). Electric potential (V) is just that, potential to do work (power). When the electric current (A) flows, the circuit requires more current (A) than what is deliverable at the current potential (V), it will increase flow at the expense of a reduction in potential (V).

When there is not enough potential (V) to flow at all, it will cut-out. It's the inadequate current (A) that is causing the problem, not potential (V). You have it backwards, looking at the "effect," not the "cause."

You can take those Energizers and use them in lower current drawing devices and still get a long lifespan out of them, because the voltage will return back to nominal. But they won't give you even half their life at high-current. As I said, when my Energizers drop below 1500-1700mAh, they are providing current and the voltage drops.
10-30-2008, 05:57 PM   #56
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i have a k200d, so hopefully my experience should be relevent for the OP.

the included energizer lithiums lasted me 1100 shots with flash used around 20% of the time and i probably used the playback mode for around 150-200 pics.

i'm now using sanyo eneloops. with a set of energizer 2500mah as spares. (not used yet)

i dont get as many shots from the eneloops (around 700 in similar circumstances as the lithiums) but my annoyance is that the flash takes a lot longer to recharge. approx 3-4 seconds after a single discharge. whereas with the lithiums, i could get around 3 flashes in 1(ish) second intervals before i'd have to wait for 2-3 seconds for a 'recharge'.

do they make a rechargeable lithium? or soon?
11-02-2008, 12:01 PM   #57
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QuoteOriginally posted by simonr23 Quote
i dont get as many shots from the eneloops (around 700 in similar circumstances as the lithiums) but my annoyance is that the flash takes a lot longer to recharge. approx 3-4 seconds after a single discharge. whereas with the lithiums, i could get around 3 flashes in 1(ish) second intervals before i'd have to wait for 2-3 seconds for a 'recharge'.
That's Lithium chemistries are far better at maintaining current than Nickel chemistries. They maintain a near constant output over various transients, non-loads, etc...

QuoteOriginally posted by simonr23 Quote
do they make a rechargeable lithium? or soon?
There are numerous Lithium battery chemistries, and yes, they make rechargeable Lithium Ion. But it does not come in an 1.5V AA option.

The 1.5V Energizer AA Lithium is a proprietary Lithium Iron (LiFe) chemistry.
The 3.0V CR-V3 Lithium is a standard Lithium Maganese (LiMn) chemistry.
Both are non-rechargeable, and their chemistries are completely different than Lithium Ion.
I.e., they vary far less and their output is extremely consistent (unlike Li-Ion, which must always be regulated).

I've yet to see a single Lithium Ion chemistry that was less than 3.6V under load (or 4.0V under charge, many times when an "open circuit," at least through transient, either).
As such, there are various complications with Lithium Ion, so much so that no device is designed for any standard Lithium Ion battery.

I.e., you will always and only find devices that use a proprietary Lithium Ion design.

Using Rechargeable CR-V3 (RCR-V3) is an option, but I've yet to ever see one read 3.0V, and the majority read more like 3.2-3.3V.
Those are either under-charged or have space taken up by internal transformers or other load circuits -- in either case, lifespan is but.
Li-Ion cells are regulated for many reasons, variance, combusion, etc... as their cells "die" at various transients or low-voltage (including 3V).
11-14-2008, 12:30 PM   #58
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Originally Posted by UnknownVT
I don't know how else to describe this difference other than the eneloops manage to maintain a higher operating voltage under the same load than the Energizer 2500mAh NiMH.
QuoteOriginally posted by bjsmith Quote
It's all about current (A), not potential (V). Electric potential (V) is just that, potential to do work (power). When the electric current (A) flows, the circuit requires more current (A) than what is deliverable at the current potential (V), it will increase flow at the expense of a reduction in potential (V).
Yes, you are correct - perhaps you may have misundertood what I was trying to say -
for the current demand - the eneloop does not have to drop its potential/voltage as much as the Energizer 2500mAh NiMH -
ie: the eneloop maintains a higher potential/voltage under the same load/current demand than the Energizer 2500mAh NiMH.

So the eneloop is more suitable for usage in the Pentax K100D (Super) than any other rechargable NiMH (or LSD = Low Self-Discharge ).

There are some confirmed re-badges of the eneloop which may be easier to obtain -

Duracell Pre-Charged
(caveat - they must be the made in Japan with white top surrounding the +ve button)

Sony Cycle Energy

There is also the possibilty that some Uniross Hybrios are re-badged eneloops - they have to have the white top surrounding the +ve button with the green/red color scheme (beware of the gray/green versions which are the only LSDs I have read poor reports about) - I understand Fry's carries these.
11-20-2008, 02:20 PM   #59
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Ansmann Digital

A German brand (Obviously, like almost everything in the World, made in China) called Ansmann makes great batteries.

I use two sets of Ansmann Digital 2850 mAh in my K100D Super and my personal opinion about them are quite positive. I sometimes leave the batteries in the camera for several days (Sometimes over a week) without taking any photographs and the batteries do not lose charge.

It looks like they also sell their products in the USA (Ansmann Rechargeable Batteries and Battery Chargers) but I have never seen them at retail stores in New York and Midwest area.
12-20-2008, 01:03 AM   #60
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QuoteOriginally posted by UnknownVT Quote
for the current demand - the eneloop does not have to drop its potential/voltage as much as the Energizer 2500mAh NiMH -
ie: the eneloop maintains a higher potential/voltage under the same load/current demand than the Energizer 2500mAh NiMH.

So the eneloop is more suitable for usage in the Pentax K100D (Super) than any other rechargable NiMH (or LSD = Low Self-Discharge ).

There are some confirmed re-badges of the eneloop which may be easier to obtain -

Duracell Pre-Charged
(caveat - they must be the made in Japan with white top surrounding the +ve button)
I charged up a set of Duracell Pre-Charged (made in Japan white top version - nicknamed "DuraLoops") back on 8/23/08 .

Put them in the Pentax K100D dSLR on 11/20/08 - almost 3 months after charge.

I depleted them tonight to the point where the camera shutdown -
so that's almost 4 months after charge .....

BUT the shot count was a whopping 1,169!!! - some, but mostly without flash - but this count for me is bordering on the unbelievably good.

From the K100D manual-


the spec for 2500mAh NiMH was 430 shots no flash -
DuraLoop = 1,169 = 272%!!

the best figures were for lithium CR-V3 batteries at 730 shots,
or lithium AA's at 660 shots without flash -
these DuraLoops exceeded both those - achieving 1,169 shots with a few flash shots -
that's some 60% better than spec for lithium CR-V3
or 77% better than lithium AA's

I am most impressed with these DuraLoops (confirmed re-badged eneloops)
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