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01-21-2012, 12:48 AM - 1 Like   #16
Brooke Meyer
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Just the facts. And an observation

QuoteOriginally posted by cbope Quote
It does indeed seem like there may be two issue here worth further controlled testing:

- Battery overcharging by the charger
- Poor voltage regulation circuitry in the camera

If there is good voltage regulation in the camera, an overcharged battery should not be a problem. Likewise, a nearly depleted battery should also work until it drops below nominal operating voltage for the camera, at which point it should shut itself off.

I try never to put a freshly charged battery directly into the camera right off the charger. This is when the battery voltage will be highest, and this will slowly drop over time to nominal battery voltage. If someone who has had focusing problems linked to apparent low battery charge and/or mirror flops which seem to be related to high voltage overcharging, then a simple test could be made using 2 Pentax batteries. Never put the freshly charged battery in the camera, but keep the spare charged ready to go, and swap the battery when the first one gets low. Then charge the fist battery and keep it ready for when the 2nd goes down. Always give the battery at least 24 hours resting period before putting it in the camera, to let the supposed overcharge dissipate.

I'd run this test myself, but I have only one battery at the moment.
That's pretty much what I do with 4 Pentax batteries and two K-5s. Its worked too, since July. There's a post below I had to chuckle at. As ex IBM PC Company / Lenovo employee, I am well familiar with Li-Ion Battery characteristics. The spontaneously igniting batteries that Sony supplied a number of PC manufacturers a few years ago was the topic of much discussion in the office.

My batteries do not puff or explode. I did not measure output with a DVM or Multimeter. But if I took a battery out of the charger when the charge cycle completed (LED extinguished) and re-seated it in immediately in the same charger, the LED lit, signifying charging, for a long time. It was the same for both chargers. I was so used to the K10/K20 charger I didn't notice it It was repeatable as were the initial "any key" firing the shutter and double mirror flops until the battery wore down a bit. ( The K10/K20 batteries used to charge a lot faster too.) Anyway, now I run them all way down, charge and remove. I don't have a circuit schematic or sacrificial charger or the desire to dive into a root cause analysis. I just want to make photographs and I do.

I happened to see a rave review about the Leica LX5 and went to Adorama or B&H (forget which) to see prices and user reviews. One guy wrote he sent his Leica back to Leica 3 times for repair before they apologized and sent him a new one. Leica! I'd still buy one if I had a need. I still buy Sony stuff even though they made exploding laptop batteries. PC Mfr's including Dell, IBM, HP et al spent many millions on warranty claims to fix "bulging electrolytic capacitors" in motherboards and monitors power regulation circuits. Many, many, many millions. They weren't careless, they got a gazillion parts that failed prematurely. Whatever ever the charger issue, its just a nuisance, like having to jiggle the handle. An IBM engineer designed the Ctrl-Alt-Del warm boot sequence in 15 minutes but Bill Gates and Microsoft made it famous for years. That's a nuisance.

01-23-2012, 02:44 AM   #17
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QuoteOriginally posted by cbope Quote
Li-Ions can be slightly overcharged without damage, as long as they are not overcharged too far.
I'm afraid then you have a different idea of overcharging. What you call "slightly overcharged" (e.g. +0.02V) is not overcharged, it's within the tolerances.

QuoteOriginally posted by Brooke Meyer Quote
There's a post below I had to chuckle at. As ex IBM PC Company / Lenovo employee, I am well familiar with Li-Ion Battery characteristics.
Yea, I chuckle when people with close to zero technical knowledge make up ridiculous "facts". We use Li-Ion and Li-Po batteries in the industry, also use Li-Po in my hobby (RC vehicles) - I know them very well. Just because the LED is lit when you place the charged battery in the charger again, it doesn't mean it starts a new charge cycle (it would definitely puff and catch fire within 2 minutes then, you can try it with a general charger set to wrong mode if you want to). A working voltage regulator in the cam can definitely handle a few 1/100th V difference, heck that is exactly its job.

Bottom line: if it's broken / malfunctioning then send it in for repair. Nothing else gonna fix it.
01-23-2012, 05:39 AM   #18
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QuoteOriginally posted by simico Quote
I'm afraid then you have a different idea of overcharging. What you call "slightly overcharged" (e.g. +0.02V) is not overcharged, it's within the tolerances.
I definitely would not call 0.02V overcharged (even slightly) on Li-Ion... I'm talking about a slight overcharge of 0.1-0.2V. This is very likely to cause problems if the camera does not have a good regulation circuit, which appears to be the case with many K-5's. Just check the posts about mirror flops, in most of the cases a common indicator is a freshly charged battery, and the symptom goes away as the camera is used and the battery level drops a bit. This points to:

1. Batteries are slightly overcharged by the Pentax charger; or
2. The cameras regulation circuitry is not well designed

Or a combination of both. This is the logical conclusion based on known facts, but someone would need to do controlled tests to really determine the cause.
01-23-2012, 11:36 PM   #19
Brooke Meyer
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Making it up.

QuoteOriginally posted by simico Quote
I'm afraid then you have a different idea of overcharging. What you call "slightly overcharged" (e.g. +0.02V) is not overcharged, it's within the tolerances.



Yea, I chuckle when people with close to zero technical knowledge make up ridiculous "facts". We use Li-Ion and Li-Po batteries in the industry, also use Li-Po in my hobby (RC vehicles) - I know them very well. Just because the LED is lit when you place the charged battery in the charger again, it doesn't mean it starts a new charge cycle (it would definitely puff and catch fire within 2 minutes then, you can try it with a general charger set to wrong mode if you want to). A working voltage regulator in the cam can definitely handle a few 1/100th V difference, heck that is exactly its job.

Bottom line: if it's broken / malfunctioning then send it in for repair. Nothing else gonna fix it.
So with my close to zero technical knowledge, let me make up some facts.

A guy charges his laptop in he airport, boards the plane and runs right back off with a smoking laptop from the Li -Ion battery. In this case it was a faulty production run of the Sony batteries but it could have been a faulty charger to achieve the same result. Overcharge a Li ION battery and if the Current Interrupt Device doesn't work, around 500 PSI the membrane bursts. Bad. And it'll happen pretty quick. That's not what's happening here.

What is true is that unlike the battery and charger used with the K10/K20, this system behaves differently. First, it charges much more slowly than the K10/K20, nearly twice as long. The battery capacity is different which mostly explains it, 1620mAh for the K10/K20 and 1860mAh for the K5. Its a different cell design and its a different manufacturer or both. The higher capacity is probably to make people happy by lasting longer.

Second, if the cell design drops voltage more quickly (normal after charging) than the previous design and /or the charger has a slightly different threshold, re-seating the battery back in the charger could result in more charging because its dropped a bit. It isn't something you should do but it worked on my earlier cameras.

Post charge, Li Ion batteries can drop up to 500mv volt per cell in a few hours. Which is why a poster mentioned waiting to use charged batteries. The output of the K-5 Battery is labelled 7.2 volts (3.6 +3.6) . The K-5 Charger output voltage is 8.4 (4.2 + 4.2). Li Ion battery cells are typically charged to 4.2v and post charge drop to 3.6. Half a volt can easily be the difference between a logic state and an indeterminate state.

Put a scope on digital circuitry and you'll see raggedy signals that don't look like ideal ones and zeroes. There are rise and fall times and thresholds and noise and all sorts of analog factors. Toss is some vibration, temperature fluctuations and supply voltage that is momentarily on the hairy edge of spec and voila - intermittent symptoms in your micro pc with lens attached.

Bottom line, if I use the battery and charger and camera as the mfr directs, it works without problem. The design point may be overly aggressive in that it isn't completely user proof. Which is when my mother would say Jaj istenem.

01-28-2012, 10:16 AM - 1 Like   #20
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Just to add a data point to this discussion, today I measured the battery voltage right after a full charge cycle on my K-5 OEM battery. Measured 8.39V and remains the same after one hour off the charger. While probably within spec, this is a bit high if the camera is designed for 7.2V nominal operating voltage. This is actually equivalent to having one extra cell (=1.2V) in the battery, assuming it is made of six 1.2V cells vs. two 3.6V cells.

I will leave the battery out of the camera overnight and check the voltage in the morning to see if it has started to drop closer to nominal voltage.
01-28-2012, 12:48 PM   #21
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Some useful info in this thread.

I think that others on this forum have also drawn a link between camera battery state and the 'mirror flop' issue affecting some cameras (K-r, K-5). A lot of those mirror flop issues were also said to occur shortly after a newly charged lithium battery was inserted into the camera.

Looks like letting freshly charged batteries always 'rest' for a period after recharge prior to putting them in the camera could be the thing to do to avoid a whole host of potential problems.
01-28-2012, 03:56 PM   #22
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With my K200D, with low light at too many occasions the camera could not autofocus (trying, then giving up). The problems vanished completely after I switched to Eneloops - so battery power seems to be an issue.

With Pentax P&S, it definitely is (or was) a problem. The Optio 60, with batteries half down, needed bright daylight to autofocus. With the Optio S4 and Optio S5i, AF performance at low light was much improved. With the Optio A10 and A40, no problems anymore. Specially my A40 is on par with the K200D with low light AF, not mentionable dependency on battery status.

@cbope:
Any charging of Li-Ins up to 100% is degrading the lifetime of the package. My (4 years old) IBM/Lenovo notebook even has a setting to expand lifetime by randomly charging to different percentages between 94% and 100%.
01-29-2012, 12:35 AM   #23
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QuoteOriginally posted by RKKS08 Quote
@cbope:
Any charging of Li-Ins up to 100% is degrading the lifetime of the package. My (4 years old) IBM/Lenovo notebook even has a setting to expand lifetime by randomly charging to different percentages between 94% and 100%.
Yep, as a Lenovo owner I'm familiar with that. In fact, it will not go into charging mode until the battery drops below a certain percentage... could be the 94% you mentioned but to be honest I don't recall exactly. Trickle charging a fully charged Li-Ion slowly kills it. Unfortunately, most laptops do this. If you run a laptop solely on the AC adapter and keep the battery in place, you will very likely destroy the battery in 1-2 years, even if you never run from the battery. Lenovo is the only manufacturer I'm aware of that tries to counter this with a much more intelligent charging system.

I checked my K-5 battery voltage this morning after letting it sit out of the camera after a full charge. It dropped only 20mV, down to 8.37V.

02-01-2012, 05:51 AM   #24
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QuoteOriginally posted by cbope Quote
Lenovo is the only manufacturer I'm aware of that tries to counter this with a much more intelligent charging system.

I checked my K-5 battery voltage this morning after letting it sit out of the camera after a full charge. It dropped only 20mV, down to 8.37V.
Actually not. My Vaio has a smart battery that can be programmed to charge 50%, 80% or full. This should prevent early deterioration.

The voltage drop is to be measured under load, the capacity to hold the voltage under load is the characteristic that really matters.

As far as I know, with Li Acc, the consumer itself has a "smart" behavior, (the case of mobile phones for ex.); all have a voltage threshold for discharged cutoff, but the indication during the discharging is based on a curve that is not fixed. So, one battery can show full on one camera and can be almost depleted on another.
Weather the battery can actually hold the voltage during the load peak is the most important factor we should care about.
Because the battery can have a weak characteristic, during such a load peak the voltage can drop suddenly, current increases accordingly. It will fry circuits before the low voltage cutoff circuit has enough time to kick in.

Food for thought: How to Prolong Lithium-based Batteries - Battery University

I hope I never run in such a situation where I kill my beloved cameras.

Octav
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