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Old Apr 18, 2008, 3:48 PM   #11
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jachol wrote:
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Investigation of CR-V3 cells and the charger

A while back I bought some rechargeable CR-V3 batteries + a charger from 7dayshop in the Channel Islands, the intention being to use them in my K100D, I'd read in the manual that CR-V3s were recommended, too late I realised that the rechargeable variety were not recommended ... I should have read the manual more thoroughly. When they arrived I charged them, and out of curiosity checked their voltages, the cells are 3 pin devices ... output voltage was around 3.8 volts at the output pins on both batteries, and about 0.3 volt higher on the centre charger pins @ approx 4.2 volts. ... Decidedly too high for use with the K100D, so they have been employed in another project where the voltage wasn't too critical.
Recently my curiosity lead me to take a look at the charger circuitry, having worked in the electronics field for most of my working life, I felt sure there would some variable element in the circuit to allow a more precise setting of the charging voltage, and compensating for tolerances in other components. This proved to be the case, and after accessing the unit by removing 4 screws from the underside of the base, I found there was a potentiometer in the circuit which did indeed vary the charging voltage. While monitoring the charge voltage ... I found conventionally that anticlockwise rotation of the pot reduced the voltage, so as an experiment I reset it at 0.3 volt lower than previous. The result was after my next charge I found the batteries were now just that much lower, measuring now 3.5 Volts. ... Jack
I would be comfortable with 3.3V which is within 10% of the designed voltage (3V).






Some report (well in 05 ) with interesting test results
















The Samsung regulated ones with 4 contacts









It measures 3.27V on the supply side to the camera












It measures over 4.15 V on the input side ( and I made the mistake earlier in thinking that it was way way over)





Even though it was in Chinese and in 2005 , it is just as relevant as today if only we can find in N Am the same Samsung crv3 batt + charger.


http://forum.pentaxfans.net/showthre...ighlight=rcrv3



I believe the one that I have (Juice brand and Moby all have 4 contacts and giving out around 3.1V) are variants of what Samsung has. They are all regulated ones.

Daniel
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Old Apr 19, 2008, 6:07 AM   #12
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Hi Daniel,
Very interesting. ... What I'd like to find out is what the battery voltage drops to when loaded by the camera, I haven't found a way to check that. On a very rough bench test I found that a cell that measured 3.6 volts open circuit dropped to 3.11 volts when loaded with a 220ohm resistor ... the load current being 3.6/220 = 0.01636 Amps or 16.36 mA. If we knew how much of a load the camera imposes, we could probably assess what open circuit battery voltage would be safe to use. Just my thoughts ... Jack
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Old Apr 19, 2008, 6:33 AM   #13
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Better pict of the batt showing the charge side (shows 4.1V) and the output side





jachol wrote:
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Hi Daniel,
Very interesting. ... What I'd like to find out is what the battery voltage drops to when loaded by the camera, I haven't found a way to check that. On a very rough bench test I found that a cell that measured 3.6 volts open circuit dropped to 3.11 volts when loaded with a 220ohm resistor ... the load current being 3.6/220 = 0.01636 Amps or 16.36 mA. If we knew how much of a load the camera imposes, we could probably assess what open circuit battery voltage would be safe to use. Just my thoughts ... Jack
Well Pentax said the camera is designed for 3V voltage of CRV3. That would mean unloaded 3 V I believe.

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Old Apr 19, 2008, 8:48 AM   #14
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Daniel,
Open circuit voltage of any cell isn't very meaningful as any battery has some internal resistance, which will drop the terminal voltage when current is drawn. Looks as if the only safe way to use CR-V3s is to use the regulated ones like Moby ... but even then from the manual Pentax do not approve of use of rechargeable CR-V3s full stop. Guess I'll stick with Uniross Hybrios. ... Jack.
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Old Apr 20, 2008, 6:54 AM   #15
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jachol wrote:
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Daniel,
Open circuit voltage of any cell isn't very meaningful as any battery has some internal resistance, which will drop the terminal voltage when current is drawn. Looks as if the only safe way to use CR-V3s is to use the regulated ones like Moby ... but even then from the manual Pentax do not approve of use of rechargeable CR-V3s full stop. Guess I'll stick with Uniross Hybrios. ... Jack.
I am no engineer. But when I test it with a multimeter, does that complete the circuit? When it shows 3.27V above, does it show the terminal voltage when a little current is drawn?

Daniel
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Old Apr 20, 2008, 9:36 AM   #16
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danielchtong wrote:
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jachol wrote:
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Daniel,
Open circuit voltage of any cell isn't very meaningful as any battery has some internal resistance, which will drop the terminal voltage when current is drawn. Looks as if the only safe way to use CR-V3s is to use the regulated ones like Moby ... but even then from the manual Pentax do not approve of use of rechargeable CR-V3s full stop. Guess I'll stick with Uniross Hybrios. ... Jack.
I am no engineer. But when I test it with a multimeter, does that complete the circuit? When it shows 3.27V above, does it show the terminal voltage when a little current is drawn?

Daniel
OK Daniel,
Yes it does complete the circuit, but a reasonably good quality voltmeter will have a high impedance so that it doesn't unduly load the circuit under test, if it did so, then results would be inaccurate, and worthless. ... similarly if you were measuring current, then an ammeter or milliammeter is applied in series with the circuit and is designed to have a very low impedance so that there is negligible voltage drop across the meter itself, which would cause inaccuracy. Most modern meters have these features. ... Jack
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Old Apr 23, 2008, 3:15 PM   #17
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I would advise everyone to stop using RCR-V3 batteries immediatelty.

I have regulated, high quality (mobypower) versions for a while in my k100d, and just noticed some very strange things. Basically, the exposure meter does whatever it wants in certain modes when applying exposure compensation. Symptoms:

-Flash never used as AF assist, even though it was popped up and lighting was terrible.

-Setting ISO to auto (200-3200).... the camera will choose 200 every time even though shutter speeds are atrocious (.5 sec and slower)

-Say you have iso3200 (manually set), and f/4. Camera picks 1/60 as shutter speed. If you set -0.5 exposure, camera picks 1/6 as shutter speed, all else being constant.

So either the camera firmware is corrupt, or the high voltage damaged the circuitry.

I will attempt warranty service. If they tell me it's void for using rcr-v3s..... and repair cost is significant, i guess I will sell it as-is and save up for a new camera.

I am not happy

Oh - and performance was not that good. It was about comparable to Sanyo Eneloop batteries, which I have a lot of now. They are what NIMH always should have been.
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Old Apr 23, 2008, 8:42 PM   #18
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Gazander wrote:
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I would advise everyone to stop using RCR-V3 batteries immediatelty.

I have regulated, high quality (mobypower) versions for a while in my k100d, and just noticed some very strange things. Basically, the exposure meter does whatever it wants in certain modes when applying exposure compensation. Symptoms:

-Flash never used as AF assist, even though it was popped up and lighting was terrible.

-Setting ISO to auto (200-3200).... the camera will choose 200 every time even though shutter speeds are atrocious (.5 sec and slower)

-Say you have iso3200 (manually set), and f/4. Camera picks 1/60 as shutter speed. If you set -0.5 exposure, camera picks 1/6 as shutter speed, all else being constant.
Sorry to hear that.
See my post Apr 16. After the initial shock , I have confined my use of RCRV3 to my plain old workhorse - DL. With a mileage of 20K , that is so far working fine there. I believe all the earlier models have more tolerance for the over-voltage(by top 5% at around 3.1v compared with the designed voltage of 3v.

The only thing I would say is to make sure all the metering test comes from perfect lighting situation rather than harsh/erratic lighting.

That is a lot less guesswork than the old days when overclocking cpu was the in thing amongst hardcore comp fanatics

Daniel
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Old Apr 24, 2008, 3:00 AM   #19
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Hi Gazander,
Thanks for your input ... I'm sure I'd be unhappy too in your situation, hope you can get the problem resolved. I'm convinced to stay with Uniross Hybrios. My CR-V3s work well in an outboard battery pack for my flash, so nothing lost. ... Jack.
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Old May 1, 2008, 5:36 AM   #20
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Jachol,

Where can i buy the Samsung SBC-1103 battery charger that i can see in

these photos that you have displayed, I have batteries that are the same

as the Samsung SBP-1103 with connections at both ends of the battery,

But i have tried several battery chargers without success as the ones

i have tried dont have connectors at each end of the charger to charge.




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