Thank you Moose !! That is about the most comprehensive info I have ever
read on these critters.
I currently have the Varta V76PX in all my bodies, but I did get a bunch of
Energizer 357 s from xxxBay. They were quite a bit cheaper than the Vartas
too, so I am going to use them from now on. I am not really too worried
about drain since my OM-4 has the newer cicuitry anyway. but this is great
info!!
Alex
----- Original Message -----
From: "Moose" <olymoose@xxxxxxxxxxxx>
To: <olympus@xxxxxxxxxx>
Sent: Saturday, May 01, 2004 11:01 PM
Subject: [OM] Re: Battery Question
>
> I did some web research on batteries a bit ago and learned a few things.
> Many silver oxide batteries come in 2 versions, high drain and low
> drain. Looking at the specs, it doesn't make any sense, capacity,
> voltage curve, everything the same except the low drain ones couldn't
> maintain voltage under short, heavy loads. So why not just make the
> better one? The answer turns out to be somewhere outside the published
> specs. It turns out that there is an internal difference (mechanical?
> chemical? both?) which made a big difference in how well they could be
> sealed against leakage. Notice I said 'made' and 'could', past tense.
> Apparently that problem has been largely solved. However, long before
> seals were improved, watch manufacturers and repairers insisted on the
> low drain designs. Makes perfect sense, they have no need for transient
> high drain capability and their work can be ruined by corrosion from
> leaky batteries.
>
> So what does all this mean to us? Well, auto exposure OMs, and all other
> similar cameras, really, use low current while metering, then high
> current during the actual exposure as electro magnets are used to
> control the shutter. So we need high drain design batteries to get
> reasonable life and reliable performance. However, battery equivalence
> charts completely ignore the difference, going only by size and voltage.
>
> With the particular size used by OMs, things are even more complicated.
> Leaving aside the lithium and alkaline versions, which are not suitable
> for OMs except in an emergency, there are 3 different silver oxide
> designs (at least). The low drain version is the 303 and the high drain
> version is the 357... and the 76! The only data sheets I've looked at
> are for Energizers. All 3 batteries are the same size and have the same
> nominal voltage. The 303 and 357 both have 175 mAH capacity, while the
> EPX76 has 200 mAH capacity and is "Designed specifically for Photo use".
> Simple, huh? Well, not really. I don't know what photo use the EPX76 is
> designed for, but it is not for OM bodies. The 303 and 357 have
> essentially identical discharge curves, starting at 1.6v, slowly
> declining to 1.55v over the first 100 hrs and staying there, dead flat,
> to 700 hrs, where they just fall off a cliff. thus they will run in an
> appropriate application accurately and reliably, then die suddenly.
> (ALWAYS carry spares, they are SUPPOSED to ide without warning!) Thus
> the 357 never has an intermediate voltage to lead to annoying, seemingly
> random, seemingly non-battery related lockups. OMs intentionally lock up
> when battery voltage under the load of shutter is relase is insufficient
> to assure proper exposure.
>
> So what about the EPX76? It's the right size and the right chemistry,
> even the same drain response when new as the 357, but...... A look at
> its discharge curve shows the price paid for the extra capacity. It
> starts out like the others, but at about 400 hrs, starts a long
> downslope to 1.2v at 750 hrs., then descends more rapidly after that,
> but not as precipitously as the 357. What all that means is that it will
> give less overall life than a 357 because it drops below the voltage
> needed to operate the shutter sooner. So the extra capacity is at
> voltages that won't operate the camera! Worse than that, it means
> unreliable response as it nears the OM minimum voltage. It may work for
> widely spaced shots, but drop enough voltage after a couple of quick,
> longer exposures to lock up on the next one. But then, but the time you
> reset the camera, try the battery check, puzzle over it and try another
> shot, it works, only to fail again apparently at random. Then you start
> asking "What the hell is wrong with this camera?" and don't change the
> batteries that seem ok until someone on the list insists that is the
> first thing to do before panicking.
>
> I believe, but don't know where I got it, that the SR44 and SR44W are
> the low and high drain designs. Anybody know? Or is the SR44 a 357 and
> the SR44W an xx76x? I also don't know if the
> Varta V76PXs you have been using are EPX76 equivalents, but I'll bet
> they are, so you should expect better performance from the 357s.
>
> Moose
>
> distinctivedeal@xxxxxxxxxxxxxxx wrote:
>
> >Thank you everyone ... I got a bunch of 357s from xBay ... I will use
them
> >in my OM-2 and OM-4, even though my -4 does have the t(i) circuit.
> >I figure they are just better SR44 silver oxide cells
> >Alex
> >
>
>
> The olympus mailinglist olympus@xxxxxxxxxx
> To unsubscribe: mailto:olympus-request@xxxxxxxxxx?subject=unsubscribe
>
> To contact the list admins:
mailto:olympusadmin@xxxxxxxxxx?subject="Olympus List Problem"
>
The olympus mailinglist olympus@xxxxxxxxxx
To unsubscribe: mailto:olympus-request@xxxxxxxxxx?subject=unsubscribe
To contact the list admins: mailto:olympusadmin@xxxxxxxxxx?subject="Olympus
List Problem"
|