Re: Best Strategy for Occasional Battery Use?
- From: ASAAR <caught@xxxxxx>
- Date: Mon, 16 Jul 2007 16:27:51 -0400
On Mon, 16 Jul 2007 12:04:49 -0700, SMS wrote:
It almost goes without saying that for AA rechargeables Eneloop is the
best option except in very rare circumstances. While the Eneloops are
2000 mAH versus the currently available 2700 mAH, the actual difference
in the number of shots you can take is not nearly as high as this
difference would suggest.
Good, you're starting to catch on. But you're mistaken about
Eneloops being "the best option except in very rare circumstances".
There are too many circumstances where they wouldn't be the most
suitable AA type to be able to make such a broad recommendation.
Regular NiMH batteries are unsuited for occasional use due to
self-discharge. OTOH, even with Eneloop, you should still do a monthly
discharge/charge cycle to maximize capacity and battery life.
Again, part right, part wrong. Regular NiMH batteries may or may
not be suited for occasional use, depending on what the use is, and
the battery expertise of the user. If the use is in high power
speedlights (such as Nikon's SB-800) and it will be used for a
couple hundred or more flashes per session, regular batteries NiMH
batteries will be a better choice than the Eneloop/Hybrid type, even
if these sessions only occur several times per year. This assumes
that the photographer is not a doofus, and knows in advance when the
session will occur, and recharges the batteries within several days
of the shoot.
As for the last statement, what information or data do you have to
support your claim that Eneloops need a monthly charge/discharge
cycle? This sounds like another of your over-the-top fabrications,
the type that you'd never invent to disparage Li-Ion batteries.
One of the other issues with occasional use with non-Eneloop type NiMH
batteries is that for maximum life, NiMH batteries should be cycled
every month (full discharge), even if not totally dicharged from
self-discharge, yet the number of cycles of NiMH batteries is fairly low
(specified at about half that of Li-Ion, but even less in practice).
"http://www.buchmann.ca/Chap10-page3.asp"; has some good information on
care and feeding of NiMH batteries. What I found interesting, and what's
been echoed by other posters on rec.photo.digital, is that the actual
number of cycles you usually get from NiMH batteries is often much less
than the often quoted 300-500 cycles. Buchmann states that the Army
(U.S.) was getting only 100 cycles from NiMH batteries in the 1990's,
and Paul Rubin who often posted in rec.photo.digital (and was a fan of
NiMH batteries) said: "I've never seen a NiMH battery last anywhere near
the vendor's claims of 300-500 charge cycles. 150 or so is the best I've
seen despite a fairly careful charge/discharge regimen."
There is a lot of good information in Buchmann's paper, but you
are guilty of picking and choosing from it to support your anti-NiMH
viewpoint. First, Buchmann doesn't agree that NiMH batteries should
undergo a charge/discharge cycle monthly. They say :
Applying a full discharge once every three months appears right.
The paper also discusses NiMH batteries that are quite different
than today's NiMH batteries. Back in the 1990's, they had about 1/3
of today's 2,700mAh capacity. Also, while it says that the US Army
was getting only 100 charge cycles from the NiMH batteries, it
doesn't state how the soldiers were using the batteries, and it's
very likely that they weren't using them in any way comparable to
how most photographers use them in cameras.
One example should be enough to demonstrate this to anyone that's
familiar with rechargeable batteries. Back in the 1990's, Radio
Shack and any number of other companies sold portable CB and VHF
radios that used battery packs holding eight AA batteries. Using
that many is a sure fire way to drastically shorten battery life.
If the soldiers used similar equipment, I wouldn't be surprised if
some battery packs went south before 20 charge cycles. And these
were analog, not digital radios, making it far more likely that the
radio would continue to operate well past the danger point for
rechargeable cells. This just isn't a problem with most digital
cameras that use two or four AA cells.
We also don't have nearly enough information to be able to
evaluate Paul Rubin's statement, and far be it from you to care,
when what he said is so easily used to spin the argument in favor of
Li-Ion batteries. What we do know from reading his messages is that
he had *many* chargers and *many* NiMH batteries, so it's highly
unlikely that everything was put aside while he dedicated his
battery use to just one set of NiMH batteries at a time for several
years. If those batteries were used in one camera and it was used
frequently enough to require a full charge every week, those 150
cycles would indicate that they were used for three years. If he
rotated them with just one backup set, they would have been used for
six years. If, during this three or six year period he used a
second camera, that would have extended the time the batteries were
used.
If you're honest (which you clearly aren't), you'd admit that
manufacturers of both NiMH and Li-Ion batteries state that they are
capable of having a very large number of charge/discharge cycles if
they are used and charged ideally. But in the real world they
rarely are, so the number of cycles will be lower for both. But
what you consistently do is pick the worst anecdotal case for NiMH
and compare that with a much larger number of charges for Li-Ion
plucked out of thin air, but you *never* state what manufacturers
claim for their products. This number ranges from 500 from one
manufacturer of NiMH batteries to 1,000, which is what most of the
other manufacturers claim. I'd be amazed if you'd provide
comparable data for Li-Ion batteries, because to support your claim
of a much greater number of use cycles it would have to be 2,000 or
more, and that's only going to be possible in Fantasyland.
It should also be noted that Buchmann's website contains a lot of
outdated information. One of its papers titled "Battery testers for
modern batteries" was written in 2001, and discusses using battery
testers/analyzers/conditioners for NiCd batteries and "medium size
batteries ranging from 600mAh to 1500mAh". Not exactly what we'd
consider 'modern'. The company's products are also intended to
support very large organizations, frequently referring to the
military, fleets, etc., and that companies using their products to
manage and service batteries often hire full time employees just to
operate their battery products. Prices aren't given online but
their battery analyzer/conditioners probably are beyond the range of
hundreds of dollars, more likely selling for thousands of dollars.
Anyone wanting to get a peek at some of them as well as how to get
pricing information can go here :
http://www.cadex.com/prod_analyzers/ordering.asp
http://www.cadex.com/prod_test/ordering.asp
.
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