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07-05-2007, 06:38 AM   #16
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Not Correct

Lithium Ion is of course consisted of Lithium materials and so do Lithium-ploymer, Lithium Magnese or Lithium Ferride and so on.

The chemical formula and substance are difference but the key element is still Lithium!

QuoteOriginally posted by bjsmith Quote
I'm looking for power EEs to critique and correct ...
BS' Blog: Li-Ion is not Lithium (e.g., Li-Mn, Li-Fe)

It also has good practices and info for using the K100D with 4xAA NiMH batteries as well.


07-05-2007, 09:07 AM   #17
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Getting anal, argumenative and missing the point ...

QuoteOriginally posted by RiceHigh Quote
Lithium Ion is of course consisted of Lithium materials and so do Lithium-ploymer, Lithium Magnese or Lithium Ferride and so on.
The chemical formula and substance are difference but the key element is still Lithium!
Yes, from an anal, chemical nomenclature standpoint, yes.

But the exact implementations of non-rechargeable CR-V3 Li-Mg and non-rechargeable L91 Li-Fe are rather specific, and have a nominal, operating voltage of 3.0V and 1.5V, respectively.

In the same regard, I have yet to see a single, rechargeable Li-Ion cell that didn't have a nominal voltage of at least 3.6V or 3.7V.
The only rechargeable Li-Ion batteries I've seen that provide less than 3.6V are the ones that are partially depleted, and they don't last nearly as long.
07-08-2007, 06:45 PM   #18
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So you think you have battery problems, I do astrophotography.

My K110D can kill 2700 mAh NiMh batteries in under 1/2 hour of continuous exposures of 1-4 minutes each. More than once I've gone through a set of Alkalines in 10 minutes. Fortunately I use AC power in my observatory and an external Lead-Acid battery in the field. Occasionally the power cable isn't in properly, and I discover that the camera stopped.

The numbers never add up. The camera draws a little over 1/2 amp when imaging, so you would think 2700 mAh would last several hours. I read in Circuit Cellar Ink that batteries are rated at a modest discharge, high current (and heat) brings them down much faster than expected.

I took some rough measurements (+- 20 %) and found the K110D draws:

Idle - 160 ma, Noise reduction 410 ma, Exposing 580 ma, and oddly the 2 second Mirror up 830 ma.

With the same NiMh batteries I took my K100D to a Zoo for two hours, 240 shots and still the battery indicator was full. This is how a battery should treated.

My wife uses Lithium Ion CRV3Rs in her istD and is quite happy with them.
07-09-2007, 03:09 AM   #19
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I have experienced it myself. Last time when we were on my girlfriends goddaughter's b-day party, we were shooting away. The little girl has just turned a year and we don't see her very often so you can imagine
Anyway after couple of shots my camera started showig low battery, and they were pics without on board flash, but the batteries had lasted for couple hundred shots by then. Anyway after turning if off for a while, I turned it on againa and made another 30 pics +/- more than half with flash and the indicator wouldn't go under half... weird, but not first time this happened.
I got used to it though

07-09-2007, 08:36 AM   #20
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Not uncommon for current to dip, but return after being off ...

QuoteOriginally posted by axl Quote
I have experienced it myself. Last time when we were on my girlfriends goddaughter's b-day party, we were shooting away. The little girl has just turned a year and we don't see her very often so you can imagine
Anyway after couple of shots my camera started showig low battery, and they were pics without on board flash, but the batteries had lasted for couple hundred shots by then. Anyway after turning if off for a while, I turned it on againa and made another 30 pics +/- more than half with flash and the indicator wouldn't go under half... weird, but not first time this happened.
I got used to it though
It's not uncommon for current to dip, but return after being off for awhile.
Continuous drain in heavier metal batteries (i.e., non-Lithium) can cause real-time current to drop more than if they weren't used continually.
This is especially in the case where the current provided by the batteries are insufficient in the first place.

A drop in real-time current causes the voltage to drop.

Remember, the "charge" indicator is not an actual measure of current-time, but the voltage being supplied.
That's how the camera "estimates" the life left in the battery ...
- "full" = nominal voltage (sufficient current)
- "half" = below nominal voltage, but still operational (insufficient current)
- "none" = below nominal voltage, insufficient voltage (wholly insufficient or no current flowing)

Cheap NiMH batteries can't supply more than 1A, and you need the newer, higher-current rated NiMH that do 2A+ for the K100D.
I've seen some reports that the K100D can use as much as 1.8A of current at 5V.

Lithium-based batteries are "always fresh" for a variety of reasons, including the fact rechargeable Li-Ion batteries "cut out" before even coming close to being drained.
Otherwise the Li-Ion cells would be destroyed.

Of course, Pentax does not recommend RCR-V3 batteries in the K100D, because Li-Ion (unlike Li-Mn CR-V3, or Li-Fe L91 non-rechargeables) has a nominal voltage of 3.6-3.7V, not 3V, and can read 4V+ when 90-100% full.
And there are countless variations in the alleged "regulated" RCR-V3s, including many forgeries, let alone even the "regulated" RCR-V3s are still 3.2-3.5V nominal.
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