AA battary capacity, Ah (?)

[lcoe]

there was thread here about battery life, and some of the new technology
wrt digital cameras (eating AA Alkalines). i got suckered into buying
another camera, and guess what, it really EATS AA'a, changing batteries
would be a full time job.

the previous owner said he used 1600mah NMiH rechargeables and got
50-60 shots, some w/flash, some without the lcd on, but was generally
happy.

Question: before i even think about buying into an expensive set up
for only occaisional use, i need to know what is the actual capacity of
the current crop of AA Alkaline battery. googling now, but find nothing
beyond suggested uses on manufacturers sites.

Thanks! --Loren

 

[Remove SPAM From Address to Reply]

Loren,

AA alkalines are higher capacity than the rechargeables,
but they are best utilized at slower rates of discharge.
Cameras are high rate-of-discharge applications and that's
why alkaline AAs don't deliver the performance you'd
normally expect.

Your friend was correct in recommending NiMH rechargeables,
you can get a decent set of 4 and a charger for about
$10 if you look for sales. Never need to pay more than
about $15.

We can discuss it further when we get together regarding
the guns, I've used NiMH and high-capacity NiCads in
many applications over the years.

Martin

 

[Ted Edwards]

Your friend was correct in recommending NiMH rechargeables,

you can get a decent set of 4 and a charger for about
$10 if you look for sales. Never need to pay more than
about $15.

Please don't do that! Those cheap chargers are either constant current
or timer terminated. Pay somewhat more and you can charge your
batteries whenever you feel like it without worrying about state of
charge. Ray-o-vac has a good charger but, personally, I like the Maha
line. My 204 isn't as versatile as some of the newer ones but it works
well. I paid Cdn$30 for it a couple years ago.
For example, see
<http://www.thomas-distributing.com/batteries.htm>

Ted

 

[Eric R Snow]

Please don't do that! Those cheap chargers are either constant current
or timer terminated. Pay somewhat more and you can charge your
batteries whenever you feel like it without worrying about state of
charge. Ray-o-vac has a good charger but, personally, I like the Maha
line. My 204 isn't as versatile as some of the newer ones but it works
well. I paid Cdn$30 for it a couple years ago.
For example, see
<http://www.thomas-distributing.com/batteries.htm>

Ted

Greetings Ted and Icoe,
What Ted Says! When I bought my digital camera I researched it (with
lots of help from RCM) and the gist of the battery life question was
to get the 1800 mah nimh batteries, made by MAHA, from Thomas
Distributing. They lasted longer that alkaline batteries in digital
cameras. And they can be thrown in the charger any time. When the
batteries get about halfway down I exchange 'em. Keeps plenty o charge
in the camera. And battery life is great. much better than the manual
said to expect with alkalines. Thomas Distributing has a battery and
charger deal. I just got four batteries as my camera uses two. Works
great.
Cheers,
Eric R Snow

 

[clare @ snyder.on .ca]

Please don't do that! Those cheap chargers are either constant current
or timer terminated. Pay somewhat more and you can charge your
batteries whenever you feel like it without worrying about state of
charge. Ray-o-vac has a good charger but, personally, I like the Maha
line. My 204 isn't as versatile as some of the newer ones but it works
well. I paid Cdn$30 for it a couple years ago.
For example, see
<http://www.thomas-distributing.com/batteries.htm>

Ted

Cannot beat the New Discovery IQ9000 universal charger for AAs, Nicad,
NiMH, or alkaline. It uses a CEC1100 Microprocessor. 200:1 negative
pulse charge technology. 900ma charge current

 

[lcoe]

That's not likely to be a useful piece of information to you. Battery
manufacturer's data sheets show AA alkaline capacity as something like
2800 mAh last time I looked, but that capacity is achieved only with
very low discharge current (e.g. something like an electronic clock). [......]
Now, digital cameras can draw several amps when powering the CCD, the
LCD and its backlight, and recharging the flash. (For example, the AC
adapter for my Canon G2 is rated for 2.7 A output). Under these loads,
an alkaline battery may indeed have a useful capacity of only a few
minutes of operation. That's why they're pretty useless in digicams.

Dave, thanks for spelling this out so clearly, and thanks to everyone
else who offered advice/experience. i believe i am _finally_ getting
the message.

NiCd, NiMH, and LiIon cells all have lower internal resistance, and can
deliver currents of several amps without much reduction in capacity from
their low-rate ratings. So all of them are better suited to powering
digicams. If your camera takes AAs, NiMH cells are the best choice
for inexpensive operation. If you need a single-use battery that still
provides a reasonable number of shots, use single-use lithium AA. > Dave

my thought early today, after reading Sphero's post, was that i just kludge
some kind of battery pack, may still do that (it worked very well on my
Tandy 100) but for now, "get up to date, DUDE!". Usenet, loveit, rcm,
sci.electronics.repair are two reasons why. --Loren

 

[Erik]

there was thread here about battery life, and some of the new technology
wrt digital cameras (eating AA Alkalines). i got suckered into buying
another camera, and guess what, it really EATS AA'a, changing batteries
would be a full time job.

the previous owner said he used 1600mah NMiH rechargeables and got
50-60 shots, some w/flash, some without the lcd on, but was generally
happy.

Question: before i even think about buying into an expensive set up
for only occaisional use, i need to know what is the actual capacity of
the current crop of AA Alkaline battery. googling now, but find nothing
beyond suggested uses on manufacturers sites.

Thanks! --Loren

Why don't you also run this by the folks over at:

sci.chem.electrochem.battery

I look around over there once in a while for the hell of it... they seem
to have some sharp people with good practical thoughts...

Good Luck!

Erik

 

[Remove SPAM From Address to Reply]

Please don't do that! Those cheap chargers are either constant current
or timer terminated. Pay somewhat more and you can charge your
batteries whenever you feel like it without worrying about state of
charge. Ray-o-vac has a good charger but, personally, I like the Maha
line. My 204 isn't as versatile as some of the newer ones but it works
well. I paid Cdn$30 for it a couple years ago.
For example, see
<http://www.thomas-distributing.com/batteries.htm>
Ted

Ted,

That's partly correct. Yes, the cheap chargers are constant-
current, but no, they are not a problem. For most NiMH cells,
the "cheap" chargers are charging at a rate less than C/10, and
are no problem even if left plugged in all day. I bought my
sets from bydusa online over a year ago, and all cells are
still going strong. I paid $7.49 for the charger PLUS four
1800 mAH cells. Bought two sets, keep one charger at home and
the other in my camera bag with fresh cells in it. Makes a
good "battery holder".

Only if you want a "fast charger" do you need to step up to the
more expensive setup with microprocessor, and yes, you can get a
great one for less than $15. For 22.95 you can have the charger
and EIGHT NiMH cells (four AA and four AAA, I use the AAA in FRS
walkie-talkies). Model V-1000 package:

http://www.batteryspace.com

This thing works great, and it's dual-power, either AC or an
included cigarette-lighter adapter. I've also used it for
over a year. I keep this one in the console of my truck for
when I need to quick-charge cells, as it's not as small as the
slow charger that I keep in the camera bag.

best regards,

Martin

 

[Dave Martindale]

That's partly correct. Yes, the cheap chargers are constant-
current, but no, they are not a problem. For most NiMH cells,
the "cheap" chargers are charging at a rate less than C/10, and
are no problem even if left plugged in all day.

There are two different types of cheap charger. They're both constant
current with no detection of end of charge. One type uses a low enough
charge rate that a full charge takes 14 hours; that's what you're
talking about. If the batteries start out partially charged, not
completely discharged, they will be overcharged - but at such a low
current that it won't hurt them.

However, the *timed* cheap chargers use a higher current that will
recharge the batteries in about 5 hours. They are a problem because
they will properly recharge *only* a specific capacity of battery, and
*only* if it's fully discharged before charging. If the battery is
higher capacity than the charger is designed for, the timer will shut
off before full charge is reached. If the battery is the correct
capacity but isn't fully discharged, then the charger will overcharge
it, and with a current large enough to damage the battery.

So, avoid the timed chargers completely. 14-hour chargers are OK but
slow. Fast chargers with end-of-charge detection are OK and fast.

Dave

 

[Ted Edwards]

There are two different types of cheap charger. They're both constant
current with no detection of end of charge. One type uses a low enough
charge rate that a full charge takes 14 hours; that's what you're
talking about. If the batteries start out partially charged, not
completely discharged, they will be overcharged - but at such a low
current that it won't hurt them.

From my reading, this seems to be somewhat cotroversial, some authors

and manufacturers claiming C/10, some C/20 and some saying even lower.
My MAHA 204 charges at C/60 after the end of the fast charge cycle.

It's probably on sacle of decreasing badness.

Ted

 

[Dave Martindale]

and manufacturers claiming C/10, some C/20 and some saying even lower.
My MAHA 204 charges at C/60 after the end of the fast charge cycle.

It's probably on sacle of decreasing badness.

Yes, in the same way that leaving the batteries in a slow charger for 24
hours is worse than removing them after 14, but better than leaving them
for 48.

I never use anything but fast chargers now myself. But slow chargers
are better for the batteries than timed chargers, and so it's useful to
distinguish between them.

Dave

 

[jakdedert]

I picked up (at a local auction) a set of six Eveready Nimh AA's, two AAA's,
a charger, two AA-to-C adaptors and two AA-to-D adaptors, all new in
unopened package the other day.

The price? $10.00.

jak

 

[jakdedert]

Oops...spoke too soon--they are Panasonic brand Nimh's.

jak

 

[Ted Edwards]

I never use anything but fast chargers now myself. But slow chargers
are better for the batteries than timed chargers, and so it's useful to
distinguish between them.

Agreed but a smart charger is so inexpensive considering how many safe
effective recharges you will get, not to mention the convenience.

Ted

 

[Sofie]

Icoe:
Yes, actually.... the Radio Shack #23-405 is only for NiCad and NiMH....
NOT for LITHIUM.
and, yes, it is microprocessor controlled and is designed to specifically
sense the unique charging curves of NiCad or NiMH, switch selectable and
will shut off when it achieves full charge as detected by the chip...... or
failing that, it's backup timer will shut it off.
It is a nicely built unit and if used properly should work just fine....
the business about charging only fully discharged cells applies mainly to
NiCad .... by fully discharging them, the "memory effect" is negated. You
really do not want to fully discharge NiMH every time you charge them....
and you don't have to.... there is no memory effect to worry about.....

 

[lcoe]

Icoe:
Yes, actually.... the Radio Shack #23-405 is only for NiCad and NiMH....
NOT for LITHIUM.

yes, i mis-spoke, thanks for noticing.

and, yes, it is microprocessor controlled and is designed to specifically
sense the unique charging curves of NiCad or NiMH, switch selectable and
will shut off when it achieves full charge as detected by the chip...... or
failing that, it's backup timer will shut it off.
It is a nicely built unit and if used properly should work just fine....
the business about charging only fully discharged cells applies mainly to
NiCad .... by fully discharging them, the "memory effect" is negated. You
really do not want to fully discharge NiMH every time you charge them....
and you don't have to.... there is no memory effect to worry about.....
-- > Best Regards, > Daniel Sofie > Electronics Supply & Repair

do you, or anyone know the cutoff voltage for the charge cycle? was thinking
of testing it by charging some partially discharged alkalines.

i see some newer chargers on-line that have a switch selectable "dis-charge"
then/charge mode. i believe it works for either type battery. Thanks! --Loren
`

 

[Sofie]

Icoe:
I would very strongly suggest that you NOT put alkaline batteries in your
Radio Shack #23-405 charger..... it is only designed for NiCads and NiMH.
DO NOT put alkalines in ANY charger not specifically designed for
alkalines..... they may explode or at the very least, get hot and make a
hell of a mess.
The cut-off voltage and charging curve is different for NiCad versus NiMH
..... that is why the charger has a 2 position selection switch..... make
certain it is set correctly for the type of battery you are charging....
notice that there is NOT a 3rd selection position for Alkaline...... do NOT
attempt to recharge alkaline batteries in this charger.
The automatic discharge and then recharge feature of some chargers and
reconditioners was meant mainly for NiCads..... to help minimize the "memory
effect" ...... not really needed for NiMH although there are those that say
it helps and others that say that regular deep cycling of NiMH is not
beneficial or even good for the battery..... my experience suggests the
latter.

 

[Ted Edwards]

Ted, or anyone, i bot a RShack "Auto Sensing" model (for ni-cad and lithium).
the manual and box says, "automatically senses full charge and shuts off".
further, in the manual it says, '`...charge only fully discharged cells...'

That's a bad sign. A smart charger should be detecting end of charge by
watching for delta-V (a slight drop in voltage). I am concerned that
they say NiCd and lithium (what lithium?) but do not mention NiMH.

another feature is a "backup" fixed timer, 1.5hr for nicad, 2.0 for lith.
it's RS model 23-405, 50% off recently. it's heavy, brick shaped, but
is it really fully automatic?

Personally, I would not go for it. Sounds wrong.

Ted

 

[Dave Martindale]

do you, or anyone know the cutoff voltage for the charge cycle? was thinking
of testing it by charging some partially discharged alkalines.

There isn't a "cutoff voltage". NiMH and NiCd cells are charged while
monitoring voltage over time. As the cells reach full charge, the
terminal voltage rate of change goes to zero, and then negative (i.e.
the voltage *drops*). This is what the chargers sense. They may also
sense the rapid rise in temperature at end of charge.

Don't put alkalines in this charger. Alkalines won't accept high charge
currents, and they'll probably burst or leak.

Dave

 

[Dave Martindale]

so i popped them in and the camera fired up fine, and i reviewed pictures
taken w/these same batteries. then i went to 'record', it tried, but
shutdown. again, sameo, sameo.

This is really just demonstrating that alkalines aren't suitable for
your digital camera - too much internal resistance.

Rechargeable alkalines, even on their first use, are worse than
single-use ones, Later discharges get worse yet because internal
resistance increases. I don't expect single-use alkalines that have
been recharged are any different in this respect.

the choice still remains to install fresh alkalines, assuming the
balance of the battery cap. could be utilized, and if i am willing
to put up with the intemittant operation of the camera. for now,
it's going to be Ni-mh, but i will not be able to resist further
testing.

Forget the alkalines. You've demonstrated that they're useless except
as an absolute last resort. Use NiMH for day to day use. Buy a set of
single-use lithium AAs for backup if you can't always be sure of having
enough NiMH batteries for a trip.

Dave