On Mon, 14 Jun 1999 23:00:09 -0700, Jan Steinman <jans@xxxxxxxxxxx>
wrote:
>Rechargeable alkaline cells cost about $1.25 to $1.50, thus my statement
>that the break-even point is 3 or 4 charges.
>For $6, you can fill your winder with enough energy for 30 rolls of film,
>then for $0, you can fill it again, and again, and again, and again...
>They do require a special charger. My first charger came with a set of four
>batteries for $20. Later I bought a bigger charger that will do up to 8
>cells of any size in any combination for about $25. I plead guilty for not
>factoring in the charger cost in the break-even analysis... :-)
>
>They do last longer if you recharge them before they go completely dead. If
>you always put a freshly charged set in the winder when you go on an
>important shoot, you won't be sucking them completely dry, and they'll last
>longer, and you'll still get 30 rolls of film if you really need it.
>
>Perhaps these aren't available in Holland. They were invented in Canada,
>and sold there for many years under the "Pure Energy" brand. Rayovac bought
>the technology license, and now markets them in America under the "Renewal"
>brand. They come in all standard sizes. The last 4-pack of AAs I bought
>cost $5.39 at Fry's Electronics.
>
>I still have the first set that I bought in Canada in 1995, before you
>could get them in the US. I would guess they've been charged a couple dozen
>times, and they still behave like a normal alkaline.
>
>They're either improving their technology, or their marketing. A pack I
>bought a year ago claims "Recharges 25 times or more." The pack I bought
>last week says "Recharges 100 times or more."
Some interesting figures, taken from
http://www.a1.nl/phomepag/markerink/battery.htm
Test data on rechargeable Alkalines vs NiMH, extracted from ColorFoto
3/97
Nominal
Peak
Nominal After After peak
after
capacity 3 cycles 8 cycles current
5 cycles
NiMH 1100mAh 1100mAh 1100mAh 12A
12A(assumed)
(Varta Accuplus)
Alkali-Manganese 1900mAh - - 3.8A
-
single-use
(Ucar Energizer)
Alkali-Manganese 1500mAh 1300mAh 850mAh 3.8A
2.0A
(BIG Alkaline)
Alkali-Manganese 1800mAh 1050mAh 650mAh 3.8A
1.9A
(Leclanche Boomerang)
Some miscellaneous notes: Main advantage of Alkali-Manganese (both
rechargeable and non rechargeable) is its low self discharge and
the flat curve of discharge (in comparison with Alkalines).
The rechargeable version is advised to be recharged before fully
drained.
NiMH has a higher internal resistance than NiCd; 'Not capable of high
currents' as stated in this electronic components catalogue....
A typical NiMH AA-cell is capable of 3.6A continous, or 6A peak [the
ColorFoto data suggests improvement on this spec]. I couldn't find
NiCd
data in AA size, but by comparing with a 1700mAh C-cell (40A
continuous, 70A peak), one can safely assume that a 900mAh NiCd is
capable of
at least 10A/17A, if not 20A/35A! You can weld wires with NiCd's!
So, for high current applications like in flashes, NiCd works best in
the field of rechargeables.
Beyond that, the self discharge of NiMH is a staggering 12-15 0.000000e+00ach
day....NiCd does 1 0.000000e+00ach day....not a problem in cellular phones and
lap tops, stuff that is likely to be hooked on to 110/22V every
day....but a large problem with infrequently used photo gear.
As for the environmental arguments: NiMH is often claimed to be more
friendly than NiCd, but one has to take into account that NiCd's can
be recycled better....so it all comes down to the choice between
resource depletion (NiMH) or toxic content (NiCd)....
Note that the sealed NiCd packs used by camera and flash manufacturers
contain a matched set of batteries, they were selected for having
an almost identical internal resistance. Different restances within a
pack means that the cell with the least resistance is drained most,
and
will be empty first, long before the others are empty! By draining the
set further, reverse polarisation of the least-resistance cell can
occur!
Throw such a set into a non-regulated charger, and you will have to
replace all batteries very soon, because overcharging is the pest for
NiCd's (often mistaken for memory effect!).
===================end quote from
http://www.a1.nl/phomepag/markerink/battery.htm
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