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11-10-2009, 07:09 AM   #76
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After I open the battery compartment, the first time I turn on the power is much worse than the second and subsequent times. I don't have to change the batteries to see this, just open the compartment, wait 30 seconds or so, and close the compartment.

Using my current sets of Imedion and Eneloop batteries, the indicator will be orange (Eneloop/Imedion) or red (sometimes using Imedion) even though the battery is fully charged (within a hundred mAh or so). If I don't use the LV trick, but turn the camera off and on again, the battery status will be green. If I use the LV trick, the battery indicator immediately goes green.

I also tried a very old set of 2100 mAh Sanyo (non-LSD) batteries. Last time I measured, their capacity was down to about 1600 mAh, and they show pretty high internal resistance. I use them regularly for my bicycle lights, which use about 700 mAh per trip. The first time I turned the switch, nothing happened. The second and subsequent times, the camera displayed "Battery depleted" and switched itself off immediately. This doesn't worry me terribly: these batteries are pretty ancient and nearly ready for recycling.

Finally, I tried some Duracell 2650 mAh non-LSD cells. I don't use these much and charged them specifically for this. Three cells required about 1400 mAh to charge (pretty good since I haven't used them in a while) while the fourth required about 2200 mAh (obviously starting to degrade more than its siblings). Since I haven't used/charged these cells in a while, I don't expect them to perform well.

When I first turn on the camera, even if I wait a fair while, nothing happens. If I turn it off and on again, the camera starts and the battery indicator is orange. If I use LV, the battery indicator will turn green after one to two seconds. If I turn the camera off and on again, the battery indicator will again be orange, but the LV trick will turn it green again. If I then open the battery compartment, wait a while, close the battery compartment, wait a long while, then turn on the power, nothing happens, If I turn it off and on again, I'm back to the orange indicator as described above.

This is all with the battery type set to NiMH. My camera's serial number starts with 3434. It was bought with 18-55mm kit lens from Newegg.

I don't know if my camera has THE problem, but it certainly has A problem. It certainly needs good quality NiMH, but that's fine. On the other hand, needing to power it on twice, or use the LV trick, is a bit strange. The indicator changing from red/orange to green when LV is activated is very strange. I suspect the strange features can be fixed with a firmware update.

11-10-2009, 04:11 PM   #77
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QuoteOriginally posted by jup Quote
I can pretty much confirm that K-x I got in Czech Republic is more picky then my old K100D or generally anything I've ever seen. However, with proper batteries, it seems to work, so at least for now, I am not putting my serial number to either list.

I do have inteligent charger that I use solely for my NiMH batteries, so they should be in pretty good state. It also tells me how much energy goes into each charge so I would know if some battery would start failing or so.

My experience insofar:

Doesn't work:
  • Energizer NiMH 2650 mAh (about 18 months old) - freshly charged, with about 2,6mAh going into each batter, worked for about 30 shots before battery depleted. No magic I was able to perform persuaded K-x to use it afterwards. Works without problems in K100D (and normally gives few hundred shots).
  • Conrad (NoName) NiMH 2500 mAh (may be 3 year old). Charged and capacity tested (all withing reasonable range of 2,5 Ah), fails to boot at all. Again, while it's no name, capacity wise it's just fine and works in K100D

Does work:
  • Freshly bought precharged Sanyo Eneloop - Gave me around 350 shots before giving up, that with heavy playing around with menus and some movies. And maybe even more importantly then number of shots - batteries were really depleted when they came out of camera. My charger was able to extract something like 20-30mAh from each of them before reaching terminal voltage of 0,9V. This means that K-x was able to use all the power that was in the batteries. Besides, I've heard somewhere that Eneloops are not precharged to full capacity, so I expect 2nd cycle to be even better.

As a side note, the open circuit voltage of non working Energizer was actually considerably higher then of working (albeit almost depleted) Eneloops, so camera definitely doesn't use open circuit voltage measurement to determine state and type of battery. On the contrary, it seems to test battery under quite heavy load, and older batteries, even with enough energy remaining, just fail this test. It's also the area where Eneloops, at least according to Sanyo claims, are even better then ordinary NiMH batteries - maintaining voltage even under heavy load. So it's not that big suprise that they work.

So my conclusion so far - I am pretty sure that at least some of the battery problems are cause by using old batteries (which just can't maintain voltage under load), or batteries charged with bad chargers (this destroys NiMH incredibly quickly). This, still, may be a problem for some - Pentax claims that camera works with NiMH batteries, and it obviously does only with some. But for me, I'll be quite happy to use Eneloops or similar. This camera is excellent, and 2 sets of Eneloops are still much cheaper then proprietary battery for most other cameras. Besides, I love the posibility to just use Lithiums for longer trips.
I disagree: first, the working K-x perform far better with brand new Eneloops. Second, I tried myself with high quality Ni-Mh (Uniross, Panasonic, GP, Sony) >= 2500mAh and the only ones working were actually the oldest and most worn out (Uniross), but only for ~350 shots.
Tested the batteries with another camera: all of them work (the Uniross being the worst ones)
Charged all of them with 3 different chargers, from smart to "dumb" ones, also with conditioning/refreshing. Nothing changed.

A working K-x should perform as good as in the best case I found: more than 1000 shots with a single set of Eneloops.
11-10-2009, 04:23 PM   #78
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QuoteOriginally posted by noou Quote
high quality Ni-Mh ... >= 2500mAh
Sadly, I think that's an oxymoron.
11-10-2009, 10:32 PM   #79
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QuoteOriginally posted by noou Quote
A working K-x should perform as good as in the best case I found: more than 1000 shots with a single set of Eneloops.
1000 is not with normal usage. The norm (also according to the manual) should be around 500 if you're very carefull with LV/video and using the display for viewing the images.

You could take 1000 shots in a row but that's not in normal usage.

11-11-2009, 03:03 AM   #80
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QuoteOriginally posted by OutOfFocus Quote
Sadly, I think that's an oxymoron.
why? consider that I excluded hybrid Ni-Mh (e.g. eneloop) on purpose
11-11-2009, 03:08 AM   #81
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QuoteOriginally posted by tomtor Quote
1000 is not with normal usage. The norm (also according to the manual) should be around 500 if you're very carefull with LV/video and using the display for viewing the images.

You could take 1000 shots in a row but that's not in normal usage.
OK, you're right: I've exaggerated...
Still 350 shots (or 500 as you said) with eneloops are far less than the declared (from the manual) 640 in normal usage and 420 with 50% flash usage, using 1900mAh Ni-Mh.
This kind of declaration tend to be conservative, that's why I support people experiencing 1000 or so shots.
11-11-2009, 08:55 AM   #82
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QuoteOriginally posted by noou Quote
OK, you're right: I've exaggerated...
Still 350 shots (or 500 as you said) with eneloops are far less than the declared (from the manual) 640 in normal usage and 420 with 50% flash usage, using 1900mAh Ni-Mh.
This kind of declaration tend to be conservative, that's why I support people experiencing 1000 or so shots.
So you have never used LV or inspected your images on the lcd? You always clicked after any focus attempt. That's the base for 640 images.

The table indicates either a few hours of image viewing or 640 shots, not both.
11-11-2009, 09:12 AM   #83
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My NiHM 2700mAh Gp power bank batteries let me fire of one shot, then they where not usable by the camera, Could still fire of my 540 Flash untill i got bored with them afterwards

11-11-2009, 09:26 AM   #84
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QuoteOriginally posted by noou Quote
why? consider that I excluded hybrid Ni-Mh (e.g. eneloop) on purpose
My experience with high-capacity batteries >= 2500 mAh is that they soon develop "rapid self-discharge syndrome" in which they lose their entire charge within a few days at most. I've had this happen across multiple brands that are otherwise associated with high-quality batteries, including Sanyo, using a high-quality single cell charger (C-9000).

The problem is that once they develop this syndrome, you get into the habit of having to recharge them just before you use them (or think you might possibly need to), and you can't rely on them to be ready at a moment's notice ("Honey, take a photo of this ...").

My non-LSD batteries that are <= 2100 mAh have not developed this syndrome. Sure, their capacity is declining with age and they lose charge more rapidly than LSD batteries, but not within a few days.

My definition of high-quality is that they can be expected to maintain their properties reasonably well for at least a year (under non-extreme conditions/usage), and I don't know of any battery >= 2500 mAh that meets that criteria.
11-11-2009, 09:51 AM   #85
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Estimated current draw

According to my manual, the K-x is supposed to be able to view photos for 390 minutes on a 1900 mAh battery.

A rough estimate of the average current draw, assuming they get every drop of energy out of the battery, is 1900 mAh / (390/60 hrs) ~= 300 mA.

Continuing my experience reported above, I left my Duracell 2650 mAh batteries in the turned off camera for about 12 hrs. When I turned the camera on, I got a red battery indicator that remained after trying the LV trick, and after turning the camera off and on again a few times.

I removed the batteries and charged them and each required only about 100 mAh to recharge. Soon after, I started discharging them at 300 mA. After 150 mAh of discharge, every battery was still reading at least 1.25 V. (I intend discharging them fully and recharging to see if that helps.)

I speculate that the camera in capture mode, but not actually taking any photos and not using LV, will be using a roughly similar amount of power as in playback mode. (If anyone has any better info, or a way to see the battery status in playback mode, please let me know.)

(Nearly) fully charged NiMH batteries (of recent manufacture) should be able to deliver a current of 300 mA and easily maintain a reasonable voltage.

Based on the above, I can't think of any valid reason to be getting a red battery indicator (with the battery type set to NiMH, which it is).
11-11-2009, 10:07 AM   #86
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QuoteOriginally posted by OutOfFocus Quote

I removed the batteries and charged them and each required only about 100 mAh to recharge. Soon after, I started discharging them at 300 mA. After 150 mAh of discharge, every battery was still reading at least 1.25 V. (I intend discharging them fully and recharging to see if that helps.)
Do you measure the voltage while under load? The problem is that failing batteries have a high internal resistance and will provide much less than 1.25 volts when you discharge them with eg 500 mA. Even if this 500mA load is only applied during a few milliseconds...

In lv the load is even much higher, eg 1500mA. If the baterry remains over 1.25volts under even such load, the k-x firmware decides that it misjudged the battery and it turns the state to green...

Last edited by tomtor; 11-11-2009 at 10:13 AM.
11-11-2009, 12:41 PM   #87
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QuoteOriginally posted by tomtor Quote
Do you measure the voltage while under load? The problem is that failing batteries have a high internal resistance and will provide much less than 1.25 volts when you discharge them with eg 500 mA. Even if this 500mA load is only applied during a few milliseconds...
This is using the Maha MH-C9000 Wizard One charger in discharge mode. The charger cycles through reports of each battery's discharge rate, discharge mAh to date, discharge time, and current voltage (from memory - I'm not sure if the order is correct). The numbers I reported were those shown by the charger while the batteries were still being discharged, and after the discharge mAh for each battery had reached 150 mAh.

I'm not sure exactly how the charger's discharge mode works. In particular, it's possible that instead of using a continuous discharge current, the charger discharges the battery at a high rate for a fraction of a second then lets it rest for a while to achieve the desired average discharge rate. If it's the latter case, I'm not sure whether the voltage is measured during the discharge period or the rest period. In any case, I know the discharge is terminated when the reported voltage reaches 0.9 V.

I will buy a suitable resistor on my way home today and measure the discharge current and voltage under better known conditions.
11-11-2009, 01:08 PM   #88
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QuoteOriginally posted by tomtor Quote
In lv the load is even much higher, eg 1500mA. If the baterry remains over 1.25volts under even such load, the k-x firmware decides that it misjudged the battery and it turns the state to green...
That sounds like a good test, based on the discharge curves shown in this NiMH comparison thread over at CandlePower forums.

Is there a similar test for orange?

Last edited by OutOfFocus; 11-11-2009 at 01:20 PM. Reason: Changed color in question from yellow (what it looks like to me) to orange.
11-11-2009, 01:43 PM   #89
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QuoteOriginally posted by tomtor Quote
So you have never used LV or inspected your images on the lcd? You always clicked after any focus attempt. That's the base for 640 images.

The table indicates either a few hours of image viewing or 640 shots, not both.
what's your point? also the guy that had reached 1000+ shots with eneloops must have reviewed his photos on the lcd and so on...

no design to argue further: here we are discussing a real problem, all the rest is useless
11-11-2009, 06:09 PM   #90
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Hi Folks, brand new Pentax SLR or any SLR owner here. Just got my K-x 2 lens kit(55-300) from J&R. Popped in year old Eneloops that were charged with the Sanyo bundled charger. Waited less than 1 min. Turned it on, no problems at all. Took a few shots, turned off and back on, no problems. Solid green battery indicator every time. Serial number 344940xxxxx
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