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01-03-2007, 02:30 PM   #1
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rechargeable lithiums..???

Smart Universal Charger with Two RCRV3 Rechargeable Li-Ion Battery (Free Shipping) - RCRV3-4

now these things are quite clearly being sold as replacements for AAs..

four AAs = 6 volts.. two of these = 7.4 volts..

one has to assume they aint gonna blow up a whole bunch of AA cameras.. or does one.. he he

has anybody used then in their pentax ???

now if they aint gonna blow up my k100d.. the extra voltage will help the auto focus speed.. i know about the alternatives but is there anybody out there running the pre k10 pentax cameras on 7.4 volts.

trog

01-03-2007, 02:58 PM   #2
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In K100D manual says explicitly that you should not use rechargable LiIon batteries. I believe it's in there, or I've read it somewhere that it's because of the higher voltage output these batteries produce.

I will not use them in my K100D. I am perfectly satisfied with my Sanyo 2500 NiMH rechargable AAs. They suffered some 800 shots so far on one charging (not all shots were in one day) and they are still alive and kicking

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01-03-2007, 03:25 PM   #3
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They should at least try to make rechargeable 1.5v Li-Ion AA's...
I agree that the ones above provide too much voltage to be good for your camera, but why not try to make something even better?

Ni-Mh doesn't last as long, plus, a set of 4 delivers 25% less voltage than standard lithium or alkaline AA's.

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01-03-2007, 03:26 PM   #4
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"In K100D manual says explicitly that you should not use rechargable LiIon batteries"

manuals tend to err on the safe side and attempt to be idiot proof..

but has anybody used these.. its quite possible if even for cheapness that the k100 uses the same voltage stabilization circuitry as the k10.. i think it uses the same auto focus motor..

treat it just as a question.. not a suggestion to blow up your camera.. i am not suggesting anybody use them.. simply asking if anybody has used them..

trog

01-03-2007, 03:37 PM   #5
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yes mo.. AA shaped rechargeable lithiums and devices that take AA shaped batteries that run of 7.4 volts stabilized down to six volts would be tomorrows batteries..

no more expensive proprietary junk thow then.. he he

trog

ps.. buts its possible we already have such a device.. which is what i am trying to find out..
01-03-2007, 03:43 PM   #6
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When I was using the K100d I tended to err on the side of safety and didn't use higher voltage rechargeable CRV3....

I did tend to use the normal disposable CRV3s though... I got 1000+ shots per set and I also found the AF was slightly faster than when I used NiMH batteries (it was even more noticable in the DS and D)... Though the AF still wasn't as fast as the K10d..
01-03-2007, 04:32 PM   #7
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a quote from a pentax engineer somewhere when ask about the faster k10 auto focus speed said.. "its probably down to the higher voltage lithium batteries"

i note the word "probably" and if the foucs motor is getting lithium 7.4 volts as opposed to the rechargeable metal hydrides 5 volts.. he is "probably" correct..

the none rechargeable lithiums seem to be 6 volts which is somewhere between the two..

i just looked on the side of my k100.. it say dc power 6.5 volts.. so we know 6.5 is okay.. but is 7.4.. he he he

some examples..

my tomtom satnav.. single cell lithium.. 3.7 volts.. car socket 5 volts..

my old lithium kodak dc4800.. single cell lithium 3.7 volts dc input 5 volts..

my leica diglux 1 twin cell lithium 7.4 volts.. dc input 9 volts..

all the above charge the battery in situ hence the higher dc voltage..

i do actually have a twin cell 7.4 volt external lithium power pack.. dare i plug it into my k100.. the answer as yet is no.. but a little more information might change that.. he he

trog
01-03-2007, 10:00 PM   #8
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I believe you're in the UK, but I am sure I bought that exact same charger off ebay, but with only one battery for $16 USD shipped.

Pentax makes many cameras that use 3.7 volt rechargeable Li-Ion batteries so they must know the technology. Yet the K100D manual says..."rechargeable CRV3 batteries may cause malfunctions due to their voltage characteristics.."

I think that if rechargeable CRV3's were OK for the Pentax DSLR''s, it would be easy for Pentax to sell Pentax branded CRV3's plus a Pentax battery charger and then tell us "other makes may cause malfunctions."

Meanwhile I know people have used RCRV3's w/o incident. It's your gear. Do as you please.

I won't use two. I'll use one. I am currently doing what another poster suggested, and using one RCRV3 in my K100D and two niMH AA's to avoid the overvoltage issue of two RCRV3's and the short term charge loss of four niMH's. If I blow up my camera, oh well.


Last edited by chedoy; 01-03-2007 at 10:03 PM. Reason: needed an edit
01-04-2007, 05:44 AM   #9
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QuoteOriginally posted by trog100 Quote
Smart Universal Charger with Two RCRV3 Rechargeable Li-Ion Battery (Free Shipping) - RCRV3-4

now these things are quite clearly being sold as replacements for AAs..

four AAs = 6 volts.. two of these = 7.4 volts..

one has to assume they aint gonna blow up a whole bunch of AA cameras.. or does one.. he he

has anybody used then in their pentax ???

now if they aint gonna blow up my k100d.. the extra voltage will help the auto focus speed.. i know about the alternatives but is there anybody out there running the pre k10 pentax cameras on 7.4 volts.

trog
Do NOT use the one you mention as it is not voltage regulated (to a lower voltage same as one-use lithium CR-V3s or AA lithiums).

For more read, see my ancient lengthy post and thread here:-

New RCR-V3s used in my *ist D! (stupid me!): Pentax SLR Talk Forum: Digital Photography Review

Or, my recent post on this FAQ here:-

https://www.pentaxforums.com/forums/pentax-dslr-discussion/1815-rechargeable-...html#post13445

In short, my comments have still not changed over time. *Regulated* CR-V3s perform very good in the K100D or *ist Dx.
01-04-2007, 07:56 AM   #10
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"RCRV3 in my K100D and two niMH AA's to avoid the overvoltage issue of two RCRV3's"

chedboy.. u are doing something i would never dream of doing.. mixing different batteries.. a mix and match battery pack is a big no no to me.. i would not even consider the idea.. but..

u have added one little extra piece of information.. u are doing something i would not do and it appears u are getting away with doing it.. so thanks.. another usefull piece of information arrives..

i am not after advice as such.. i am fully aware of all the posibilities.. what i am after is someone that has done what i am thinking about..

it has been said that one of the reasons that pentax moved over to proprietory twin cells lithiums for the K10 was to avoid all this mix and match varying voltage stuff that now comes with the use of third party AA shaped batteries..

at one time an AA battery was an AA battery.. they came at 1.5 volts per cell and that was that.. four of them in series added up to six volts.. now they come in several guises and including the single cell lithium recharable designed to fit where two AAs in series would fit.. can be anything from 4.8 volts to around 8 volts for a four AA type pack..

from this point of view pentax have solved many a potental problem by saying.. right then lads its our propriety lithium pack at 7.4 volts and thats your lot..

i am trying to find out one simple thing.. will my k100 tolerate up to 8 volts without damage or will it not..

i know ts good for 6.5 volts i also know it will have a safety margin built in.. everthing does.. but what is that safety margin..??

i am a tweaker by nature my PC with amd 64 bit cpu for example is running at 3000 mhz it will run at 3200 mhz.. it was sold to run at 2400 mhz.. i also know why this is possible..

i also know or at least think.. that for ease of manufactor and the making of as few parts as possible the voltage regulating circuitry in the k100 could be exactly the same as that in the k10..

to be able to make just the one part.. then rebadge.. rebox.. rename.. reprice.. and cover all market segments is a modern manufacturers dream..

so the idea that k100 might well operate at the same voltage as the k10 isnt entirely beyond reason..

trog
01-04-2007, 11:37 AM   #11
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Yeah, mixing batteries can be bad. You convinced me that I don't need to risk finding out how bad and have decided to switch to eneloops that came yesterday. They came with a nifty little plastic storage holder. That will end the occasional problem I've had setting my pants on fire with loose batteries and coins in the same pocket, providing I use the holder.
01-04-2007, 11:49 AM   #12
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QuoteOriginally posted by trog100 Quote
"
i am trying to find out one simple thing.. will my k100 tolerate up to 8 volts without damage or will it not..
..
It's more like 8.4 volts. I checked out my various li-ion batteries (NP500, NP700, BLM1) and they all were at 4.2 volts per cell. The exception was that RCRV3 that I bought which is at 3.9 volts fully charged. Maybe there is an additional limiter circuit onboard on that one. The people that are using two RCRV3's in their pentax cameras are surely choosing batteries that run lower output voltages.

As for the camera design, the computer circuitry is likely 3.3 or 2.5 volts anyway. I believe the SD card standard limits it to 3.3 volts. So there is definitely a internal regulation circuit. The motor and its interface circuits might run off the battery though.

Last edited by chedoy; 01-04-2007 at 11:51 AM. Reason: like to eidt for spelling
01-04-2007, 11:57 AM   #13
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Here's a DPR post that might help you.
Re: unique battery option...: Pentax SLR Talk Forum: Digital Photography Review

Except that ebay link in there is no longer valid.

Last edited by chedoy; 01-04-2007 at 11:58 AM. Reason: bad link
01-04-2007, 12:07 PM   #14
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"The motor and its interface circuits might run off the battery though"

yes from what i read they just get what the battery aims at them.. which explains the faster autofocus speed from the higher voltage combinations..

most short usage motors are quite tolerant to over volting.. so i dont think the motor would be a problem..

also most batteries fresh off charge will record higher than their rated voltage.. a 12 volts lead acid cell for example will read 14 volts fresh off charge.. left to stand for few hours or with the a very slight load applied it will drop closer to its rated voltage..

a fresh off charge no load voltage reading isnt a fair one.. i think the 7.4 volts i quoted is nearer the mark..

the higher voltage is refered to as "surface" charge or something like that.. it soon bleeds off..

trog
01-04-2007, 12:11 PM   #15
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QuoteOriginally posted by chedoy Quote
. . . the occasional problem I've had setting my pants on fire with loose batteries and coins in the same pocket. . .
Whoa - ouch!
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