I would like to add to Cory's comments that my research on chargers shows that many do not fully charge NiMH, many shut off too soon. Some only charge to 85% (specifically the Energizer 15 minute charger) and then go into trickle charge, you have to leave them in trickle for about 24hours to top off the batteries all the way. If you get 300 shots from a set of fully charged batteries, a set charged to 85% only gets you maybe 200 shots (seems a lot less than 85% of 300 doesn't it?) that's because the final voltage is not as high. The charger with my Digital camera only charged to 1.2v, (final voltage should be at least 1.425 checked with a digital multimeter) the guy I bought it from said the batteries don't last long, I imagine they didn't, they do do better with a double charge from that charger (9 hour cutoff).
I still haven't decided whether a pulse charger like the Maha 401, or a
gee-whiz high tech charger like the LaCrosse is a better way to go. Anybody
want to expound the relative performance of the two.
graywolf
http://www.graywolfphoto.com
"Idiot Proof" <==> "Expert Proof"
-----------------------------------
Cory Papenfuss wrote:
The *ist DS can use two CRV-3 Lithium disposables, four AA NiMH
rechargeables, four AA Lithium disposables and, in a pinch, four high
energy AA alkalines. CRV-3 and AA Lithium disposables cost about $8
per set in quantity (CRV-3s are a little more expensive, but are more
convenient to load and unload). They have excellent shelf life and
generally run about 1100-1300 exposures per set in average use.
NiMH AA rechargeables are good, if more maintenance work. It's
recommended to buy at least 2300mah capacity and to also invest in a
good quality charger (the Maha MH-C204W from thomasdistributing.com is
considered one of the best). Good quality cells normally run around
$15 per set, the Maha charger above is about $29. Properly maintained,
a full charge on a set of NiMH AAs (2300mah) runs about 500-700
exposures. Since NiMH don't hold a charge sitting on the shelf well,
they should be charged every week or so if you're not shooting enough
to exhaust them sooner than that.
AA Alkalines are an "emergency use" option only. Good ones generally
last 100-200 exposures, they don't have enough current to drive all
the camera's functions however, and their performance is quite variable.
(CRV-3s are also available in Lithium-Ion rechargeable form. These are
not recommended by Pentax, as many of the available batteries are
over-voltage for the DS. Some are available with 3.0V output, but they
are expensive and you're back into maintenance land. I don't use them,
some others I've heard of have used them successfully. )
Given these options, I find there are three good strategies for power:
- If you're shooting relatively few exposures per week, a set of
Lithium disposables in the camera and one backup set in your bag is an
effective setup. It's also good setup for traveling as you don't have
to manage with power adapters, chargers, etc. (On my trip to the UK, I
brought 5 sets of CRV-3 and AA Lithium batteries. I consumed the third
set 3,600 exposures later. No maintenance, light weight, very little
extra space consumed in my luggage, no juggling of adapters and cords,
etc.)
- If you're shooting a regular amount per week (typically 200-400
exposures like I do) and want to minimize costs with light maintenance
overhead, one set of NiMH AAs in the camera and a set of backup CRV-3
Lithiums in the bag is a very cost effective and useful kit. I charge
the NiMH AAs once a week, regardless of whether they are showing low
voltage or not. (I only used the original CRV-3s that came with the DS
when I went to the UK, as I bought the NiMH AAs with the camera and
never ran out of power in the field.)
- If you're shooting a LOT per day, a thousand or more exposures on
frequent shooting days, three-four sets of NiMH AAs and a pair of
chargers saves money in the long run at the expense of maintenance and
management time. I've not felt the need for this amount of
rechargables yet.
Pentax makes an AC adapter for the D/DS. It's a little pricey but
should work well. Others have purchased generic AC adapters with the
right voltage/current/plug polarity instead at 1/5 the price that work
well too. I haven't seen the need for one yet, it's mostly useful if
you're doing astrophotography or tethered shooting.
Godfrey
I would agree with this with one exception. To really get the most
out of your batteries, I've found it necessary to get an over-engineered
charger. I bought the LaCrosse BC-900 because it has four independent
charging/discharging circuits, LCD readouts for each batterys' voltage
and current accumulated, and different "modes" for
charge/discharge/test/refresh. It's only a 1.0A max for four (1.8A for
two), but any more than that and you'd be abusing the batteries pretty
badly. I've found that supposedly "identical" cells have widely varying
capacity. With the BC-900 I can match cells' capacities.
... the self-discharge of the NiMH is kinda a pain if you shoot
infrequently. If it's been longer than two weeks since you charged
them, you should top them off before you use them if you expect to get
much life out of them. Still, they're cheap enough to have a few sets
and rotate through.
-Cory
--
*************************************************************************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
*************************************************************************
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