Pretty much correct. The "memory effect" is almost completely a
myth... it was only prevalent on 1960's/1970's vintage NiCd cells under
automatic cyclic charge/discharge cycles used for NASA robots, etc. The
much more common cycles are series cells repeatedly cycled and having some
weaker cells getting progressively more undercharged and abused. The
other common failure mode is people so worried about memory effect that
they keep cells on trickle charge for storage. It promotes other problems
that reduces capacity.
I've got some cheapo NiMH AA's (2150 mAh) that only last about 50
frames in my -DS. Once I got some good quality Energizers, it's more at
about 500. I also invested in a GOOD battery charger (LaCrosse BC-900)
which charges cells individually, as well as being able to give valuable
feedback on capacity, discharge, variable charge rates, etc. Bottom line
is with good quality NiMH cells and a good charger, they work fine. If
you haven't used the camera after a month or so, you may only get 50% if
you don't top them off first. Still... not a bad tradeoff.
-Cory
On Wed, 30 May 2007, Godfrey DiGiorgi wrote:
> NiMH batteries generally have little 'memory' effect, but there is
> definitely a widely varying range of battery quality in the NiMH
> marketplace. They also have a lifespan, measured in full charge
> cycles, to which the quality of the charger contributes both
> positively and negatively. If you're getting that few exposures per
> charge out of the NiMH battery set, they may well be on the way out.
>
> I bought a set of Power2000 brand, AA NiMH 2400mAh batteries when I
> got my DS body at the end of 2004/beginning of 2005. They came with a
> matched charger. My general rule of using them is to charge them once
> a week, whether I made many exposures or not, and they've lasted
> well: continue to provide about 600-800 exposures per charge when I
> put the camera to heavy use for a weekend session.
>
> My use of the DS body has dropped off considerably since I got the
> K10D so I've fitted Everready Energizer AA E2 Lithium disposables
> now. The current set are over a year old, have made about 900-1000
> exposures, and are still powering it without any problems. The AA and
> CRV3 Lithium disposables are the best batteries I've found for the DS
> and are what I'd recommend. At $8-10 per set, and typical lifespan of
> 1100-1300 exposures, they're not too expensive to deal with.
>
> There are CRV-R rechargeables on the market that also fit. Some of
> them deliver voltage which is too high, and could damage the camera.
> They're not recommended by Pentax. If you find a set that are within
> spec for the camera, I know that there are quite a few people who use
> them and report that the slightly higher voltage they supply improves
> focusing.
>
> But I don't trust them. I'd recommend buying AA Lithium disposables
> in 8 and 16 pack sets to get the best price, and using those instead.
>
> Godfrey
>
>
> On May 30, 2007, at 1:20 PM, Barry Rice wrote:
>
>> My wife photographs with an istDs (which used to be mine), while I
>> use a
>> K10D. I'm having some battery problems with her camera (sometimes
>> the NiMH
>> rechargeables seem to hold only enough charge for about 50 shots,
>> especially
>> if the batteries haven't been used for a while).
>>
>> I think that maybe I have to exercise the NiMH rechargeable
>> batteries more
>> completely occasionally, since I tend to recharge at the end of
>> each day
>> when I'm using them even if they're just partially depleted. Online
>> battery
>> FAQs suggest that NiMH don't have much of a memory effect, though.
>>
>> Any advice? And I've been wondering---can I can get rechargeable Li-
>> ion
>> batteries for istDs?
>
>
>
>
--
*************************************************************************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
*************************************************************************
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