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02-06-2007, 07:09 AM   #31
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I have this "problem" since day one. The Eneloop that show "depleted" after 300 shots could still snap another 100 shots after 1 week of sitting in the camera without charge. Called Pentax and they said the camera is designed for CRV3. Oh well.

If I knew this I wouldn't buy the K100D, I was thinking I could save a few bucks on spare batteries. Now I have spent money on new rechargeable batteries and charger. That is the same amount of money, if not more, to buy a spare propriety battery if I chose a camera that didn't use AA.

02-06-2007, 01:09 PM   #32
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the problem here is people expect a battery life indicators to tell them how much life is left in the batteries..a reasonable assumption..

with alkaline batteies life was easy.. a battery life indicator is a simple volt meter.. it reads voltage..

a new out of the packet alkaline reads 1.5 volts per cell under no load.. 6 volts for four of them.. as it runs down it the voltage follows a linear pattern.. 5 volts from a pack of four means half used up.. 4 volts is flat or fully used up.. a volt meter works perfectly as a battery life indicator..

other battteries behave differently a nicad or NiMH battery has an initial higher surface voltage when fresh off charge.. this rapidly drops off to around 1.2 volts per cell.. or 4.8 volts per set of four..
the nominal 4.8 volts is maintained untill one cell in the pack goes flat..

if all cells are equal (they never are) the set goes from being okay to flat in a few seconds.. with batteries like this no volt meter (battery life indicator) is of any use..

one of the reasons i bought my k100 is because it can use NiMH batteries.. but as i said earlier i know how to use them.. they have more uses than just in a camers and i have dozens of the things..

the k100 is bit of an oddity with its useless confusing battery life indicator when certain batteries are used.. but once u know this and know the limitations of different battery types it isnt so much of a problem..

lack of knowledge of how batteries work is the problem.. having a camera that can use three different battery technologies simply compounds the lack of knowledge problem..

hence the k10 and its (idiot proof) lithium only approach..

trog

Last edited by trog100; 02-06-2007 at 01:15 PM.
02-06-2007, 01:20 PM   #33
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I admit I didn't know much about NiMH before I had to find the "right" batteries for the K100D. But if you read my post again, the camera actually said "batteries depleted" and shut off. But in fact the batteries still have juice for 100+ shots, mostly with flash too! So how do I know when my batteries are actually empty???

To trog100: Now, how does this fit into your explanation of how NiMH work?
02-06-2007, 01:33 PM   #34
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QuoteOriginally posted by SimSV Quote
I admit I didn't know much about NiMH before I had to find the "right" batteries for the K100D. But if you read my post again, the camera actually said "batteries depleted" and shut off. But in fact the batteries still have juice for 100+ shots, mostly with flash too! So how do I know when my batteries are actually empty???
Its not just you SimSV, even the camera doesn't know when the batteries are actually empty - that is why it shuts off. As others have said, I don't think Pentax will ever acknowledge the problem. I called them and they gave usual stuff about bad batteries, bad charger etc. When I persisted, they said to send it in and that they will have a look at it. But it doesn't inspire too much confidence if they claim that they are not aware of any such problem with NiMH rechargeables.

I think, the camera should be calibrated to work for the lowest common denominator. Every type of battery chemistry has a typical discharge curve. We are looking at Alkalines, NiMH and Lithiums. I am sure some genius in their R&D can figure out a logic that can manage these three types safely and reliably. Heck, the Minolta 7Hi I had in 2002 could do it, and so can my mom's Canon P&S, there is no reason why they can't do it for the K100D. But to do it, they first have to acknowledge that there is a prob - and I don't see that happening soon. Maybe if all of us K100D/K110D users here start calling them up twice everyday to complain about it....

Till then I think I can get by with the Rayovac Hybrids (still testing, but looks promising) and a couple of sets of Lithiums as a back-up. Apparently they have a very long shelf life - the ones I saw at Walmart yesterday had dates from 2012 to 2015, but they are not cheap.

Cheers
Teja

02-06-2007, 01:41 PM   #35
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Pentax suggested me to send it in for inspection too and I had the exact same thought as you. How are they going to repair the camera if they aren't aware of the problem? They may test the camera with their own batteries and they may never be able to duplicate the problem we are having. Then I will get it back after 2 weeks with nothing done to it. Or worse, they may find my camera to be faulty and replace it with a refurb'ed unit. (common practice with most electronic, e.g. cell phones) I didn't spend 1k on a refurb'ed camera...
02-06-2007, 03:00 PM   #36
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"To trog100: Now, how does this fit into your explanation of how NiMH work?"

the voltage figures i quoted are no-load figures.. any battery will suffer a voltage drop under load.. the k100 for example does seem to have a shut off point.. i am gonna guess here at around four volts.. its not based on the lower overall voltage of NiMH batteries..

the camera reads the voltage as it switches on.. the act of powering up puts a heavy load on the batteries.. if the set of four dont maintain the shut off four volts the camera powers down..

some nimh cells will not deliver the load the camera needs and maintain enough voltage.. some will only do it for a limited time.. give then time to recover and off they go again..

they dont like cold weather either..

all it takes is one weak cell to suffer too much of a voltage drop and the camera powers down..

i have my own battery tester.. it dosnt just light a small bulb as most do.. it puts a heavy 2 amp load on each cell.. i used to spend time sorting out the poor cells when a set of four failed to deliver..

now they can be bought so cheaply it isnt worth the effort..

NiMH is not a perfect technology.. but if anyone has read the stories of exploding laptops they will also know that neither is rechargable lithium..

trog
02-13-2007, 09:30 AM   #37
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Update on Rayovac Hybrid Batteries

Ok, its been over a week since I popped in my first set of Rayovac Hybrids into the K100D (straight from the pack, without any charging), and the camera indicator is still showing full. I haven't taken many pics - maybe 60 or so, but it sure seems that the Hybrids offer similar performance to the Sanyo Eneloops, but at 1/3rd the price (Eneloop = $3 per battery, Hybrid = $1 per battery).

I am plenty happy that the batteries still show full after a week in this super-cold mid-west weather. I went out and got three more sets for exclusive use with the K100D, and a set of Lithium CR-V3s as backup.

Leaving for India tomorrow, all set. The Quantaray 70-300 DI (Tamron version) was delivered last friday, and I am now covered from 18mm to 300mm. But my main lens will be the Sigma 24-135mm. Will post some shots after I return.

Cheers
Teja
02-13-2007, 10:00 AM   #38
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QuoteOriginally posted by Teja Quote
*snip*
Leaving for India tomorrow, all set. The Quantaray 70-300 DI (Tamron version) was delivered last friday, and I am now covered from 18mm to 300mm. But my main lens will be the Sigma 24-135mm. Will post some shots after I return.

Cheers
Teja
Good luck, have fun, and come back with lots of pictures!

NaCl(I'm visiting "scenic downtown Huntington" but it's not quite in the same league as going to India)H2O

02-13-2007, 12:12 PM   #39
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You could have a bad cell as mentioned previously.
One way to tell is if you have one that gets warm.

Also, I've found that during heavy use, the batteries will get warm
and won't put out as much voltage till they cool down. This is probably normal
and a byproduct of the chemical process, internal resistance effects too.

However, if, as you mentioned before, it was intermittent, it could be as simple as dirty contacts.

An old trick to cleaning contacts is to use a pencil eraser.
Just 'erase' the contacts and the battery ends as well. This is abrasive enough
to get the job done, but not so much as to wear down the metal.
02-13-2007, 05:55 PM   #40
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Did anybody ever try cleaning the contacts in the camera? If there is some kind of residue on them from assambly, it might be the source of all the problems. Just a thought...

Another thought. Are AAs sheilded? Maybe they are suffering some side effect from being so close to all the magnetism from the SR mechanism.
02-13-2007, 06:30 PM   #41
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QuoteOriginally posted by Teja Quote
Yep new batteries - about six months old. And the set I used to test the problem brand new, just bought last month.

And I am not new to NiMH, have been using them for years now. Also, the LaCrosse charger can identify a bad cell in a set as it has four independent charging circuits.

My guess is that the prob is with the camera itself. Will have to wait and see what Pentax USA has to say about it.

Teja
QuoteOriginally posted by Teja Quote
My guess is that the prob is with the camera itself. Will have to wait and see what Pentax USA has to say about it.
My guess is it's the batteries.

... but why do you have to guess? Test those cells on that BC-900 and find out what the capacity is. If you have a weak cell, that's your problem. If you've ever depleated the cells down to a bare minimum, you have likely reversed the current through one cell (whichever was weakest) and ruined it. Test and you will see.

Also, slow charging and 'topping up' NiMH is the best way to ruin them. Charge them at 1000mA and take them out of the charger when they are done. There is a little voltage dip NiMH cells do when they are done charging that smart chargers look for. It's only a few microvolts when charged at 1C and it is less when the charge rate is less. It's easier for the charger to end charging at the correct time when you charge at a higher current.

NiMH are best charged at 1C. At 1000mA, you'll be charging at 1/2C so you are still being very easy on the batteries.
02-13-2007, 11:38 PM   #42
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Here are some discharge test data for Energizer 2100 cells. Note Sanyo makes the Energizer 2100 cells and both are identical.



It is quite possible to make a battery meter that functions properly with NiMH. It's not even that hard. What's more, it's not particularly difficult to design a circuit that understands what type of cells are connected. There are many examples of universal chargers that can identify alkaline, NiMH, NiCd, LiIon, and lithium polymer. The only types of cells that I don't believe are possible to distinguish are alkaline and rechargeable alkaline. The characteristics are too close.

I will also point out that the lower internal resistance of NiMH over Alkaline has two particular characteristics that are worthy of note here. One, NiMH can output significantly more current than Alkaline batteries and they are happy to do so. Under load, NiMH will not sag nearly as much. I have no doubt, when the camera is operating, healthy NiMH cells maintain more voltage than Alkaline. Any testing I've done has proven this out. Second, the low internal resistance of NiMH causes them to go flat over time, regardless of load. Even just sitting on the shelf, an NiMH cell will be nearly useless after 45 days without a fresh charge.

I use Energizer 2500 cells purchased from the grocery store in my K100D. Sanyo makes these cells for Energizer and they are very good. Higher rated cells are made by Energizer themselves. I understand the higher rated cells are good also but I can't buy them at the grocery store for $14 CDN for 4 cells.

My battery indicator shows full. I've taken about 400 so far (50, or so with flash). I'll post up when I know how long these cells last.

How many shots do we need from a set of cells? Seriously?

Oh... and the La Crosse BC-900 chargers are nothing short of marvelous. There is no better consumer grade charger, for the money. I prefer firmware 0.32 to 0.33 as 0.33 has lower thermal runaway threshold which causes the charge to cycle. Always have a s small fan blowing over the BC-900 when it's charging. At any setting over 500mA, the cells can overheat and melt down.
02-14-2007, 02:40 PM   #43
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QuoteOriginally posted by Tom Brown Quote
My guess is it's the batteries.
I don't know how many of us here also follow dpreview. There is another battery thread

Re: K100d battery issue again: facts and figures: Pentax SLR Talk Forum: Digital Photography Review

also check the first post in that discussion. A couple people are testing the cutoff voltage. The first one reported it to be 4.66V and the other one is in the 5.3V range. (I am no expert on electronics and I have no idea how 4x1.2V NiMh can power something that has cut-off higher than 4.8V.)

We can all agree that batteries do make a difference. Not trying to prove that wrong but that doesn't mean Pentax did a good job. If there really is a cut-off voltage with that big of a range, that's one lousy manufacturing process. Yes, eneloops seem to work even in the "bad" bodies, but they can last even longer if the bodies were better made. Same goes for lithium AA or CRV3, it all depends on how "it works" is defined. If one body can take 1200shots with CRV3, and the next body can take 1500shots under the same condition, are both camera good?

I am not bashing Pentax or any camera model. I just don't get why some people try to steer away from the camera, or even say it's the lack of NiMh knowledge that caused the problem.
02-14-2007, 03:25 PM   #44
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QuoteOriginally posted by SimSV Quote
A couple people are testing the cutoff voltage. The first one reported it to be 4.66V and the other one is in the 5.3V range.
I've been following that thread. I don't think the data being collected is particularly relevant because NiMH cells have an ability to recover voltage when unloaded. This means the time from load to test is absolutely critical. What's going through that thread is grotesquely unscientific.

As for how four "1.2" volt batteries can operate a camera designed for four "1.5" volt batteries, those voltages are almost irrelevant. A NiMH hot off the charger can easily be 1.6v and continue above 1.5v for the first few dozen mAh of it's work cycle. That 1.2 is a loaded average and I would also contend it's a bit arbetrary. That number was more appropriate back in the early days of NiCd but it's less appropriate today with high capacity NiMH that often average closer to 1.35v.

Alkalines are rated at 1.5v, and they rarely start higher. That number is where they start their life, not an average number. A fresh alkaline will quickly sink into the 1.4x volt range within the first few mAh. Alkalines also have the ability to recover voltage so pulling them from the camera and measuring them is just as time sensitive as NiMH.

Under any load, particularly when using a flash, fresh NiMH batteries will maintain higher voltage than fresh alkaline cells. Alkaline cells are not suited to drive high loads.

I guess what I'm saying is there are numbers floating around that pretend to be valid data but I think they are highly questionable. Particularly where Teja has a charger that can perform a capacity test on his cells, let's see how they perform. NiMH cells are notorious for capacity variances over their life for a variety of reasons. Let's see *all four* of those 2100mAh cells tested at 1900+mAh before we start talking about the camera.
02-14-2007, 03:37 PM   #45
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QuoteOriginally posted by Photo Tramp Quote
My 2500 and 2700 MAH batteries are useless after 3 or 4 recharges and I don't know why.
It's almost certainly your charger. Most chargers don't charge properly.

I suggest you pick up either the Energizer 15 minute charger (Energizer 1 hour charger not nearly as good) or a La Crosse BC-900. Both are excellent. The Energizer is super quick and the La Crosse will let you test and even refresh tired cells.

Note that extensive testing has been done using the 15 minute charger and it does diminish the useable life of the cells but only by about 10%, or so. It acomplishes this feat with new charging techniques that stray from the normal technique of applying a constant current for the duration of the charge and watching for a tiny dip of a few microvolts to signal the end of the charge. In other words, 99% of chargers cannot safely charge faster than 1C (ie: the fastest 2500 mAh cells can be safely charged is 2.5A) while the Energizer (and there are starting to be a few more pulse style chargers) can safely charge at 4C (That's 8A since the 15 minute designation comes from 2000 mAh cells).

With a proper charger, NiMH cells should gain capacity during the first dozen, or so, cycles.

Here is more than you ever wanted to know on the topic.

Last edited by Tom Brown; 02-14-2007 at 03:42 PM.
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