NIMH (rechargeable) and Alkaline non rechargeable

nick c wrote:

Paul Heslop wrote:
Pebble wrote:
Thanks Paul,
Still don't know if they are swappable though? My camera for instance takes alkaline OR NIMH, it mentions in the manual . Of course I use NIMH because the alkaline batteries send you broke. What I meant was if a radio, torch etc doesn't mention in the manual about using NIMH, just gives info like "insert 2 AA Alkaline batteries as shown in the diagram below" can NIMH be used in place of them?

I think usually they recommend alkaline due to its having a long
lasting effect, plus if I remember it rightly when they drain they
don't ooze that gunk all over, so for torches etc they are much better
than the old style battery. I am not sure that NIMH would last as long
in a standard device as an alkaline but as long as you don't mix and
match they should be fine.


All my standard flashlights (torches)have NIMH batteries. The newer
hi-powered flashlights are supposed to use li-ion batteries. I also use
NIMH batteries in my portable radios, clocks, CD players, automatic lawn
sprinkler system, home automatic heating/air conditioning thermostat,
and just about anywhere alkaline batteries are called for. Exception
would be where the manufacturer states NIMH batteries should not be
used. I once read that notice for an article I bought but now I can't
remember what that article was.

I don't think I have ever seen that notice on anything, but then again
I might have just binned the instructions :O)
--
Paul (Need a lift she said much obliged)
-------------------------------------------------------
Stop and Look
http://www.geocities.com/dreamst8me/

On Thu, 18 Jan 2007 12:59:49 +0000, Pebble wrote:

Hi all,
Coming to grips with battery terminology. Have read lots of tutorials, opinions, grazed google posts and haven't really found out if one can put charged NIMH batteries in the place of non rechargable Alkaline batteries. I realise that voltage seems to be higher in Alkaline non rechargeables than the NIMH rechargeables. I think there is a loss of quality in signal for torches and radios and some other gear ??
Trickle charge versus fast charge ??
Thanks, all opinions welcome.

I've not observed any real compatibility issues. IMHO the faster the
charger, the shorter the ultimate life of the batteries, generally. That
is probably not so much of an issue if you buy an upper line 'intelligent'
charger.

On Thu, 18 Jan 2007 16:16:50 GMT, Paul Heslop wrote:

All my standard flashlights (torches)have NIMH batteries. The newer
hi-powered flashlights are supposed to use li-ion batteries. I also use
NIMH batteries in my portable radios, clocks, CD players, automatic lawn
sprinkler system, home automatic heating/air conditioning thermostat,
and just about anywhere alkaline batteries are called for. Exception
would be where the manufacturer states NIMH batteries should not be
used. I once read that notice for an article I bought but now I can't
remember what that article was.

I don't think I have ever seen that notice on anything, but then again
I might have just binned the instructions :O)

I also have never seen that notice, and as far as I can tell it's
because the primary reason would be to avoid using NiMH cells in
situations where they could easily become damaged, or where with
some poorly designed electronic devices, the rapid voltage drop that
occurs when one or two cells go flat could cause the loss of memory,
such as radio presets, configuration settings in mp3 players, etc.

Fortunately, many digital electronic devices will power off before
battery damage can occur, but as I said, there are some devices
where this doesn't hold true. For those, the normally higher cost
of using alkaline batteries can be lower than NiMH batteries that
become damaged after only a small number of charge cycles.

Using NiMH batteries in analog devices can often be very bad for
the life of the batteries, since they'll usually continue drawing a
significant current long after one or more cells become depleted.
With flashlights that use filament bulbs, the main danger would be
if they were used unattended, such as letting a camp lantern stay on
overnight. But in normal use, as soon as the first NiMH cell
becomes exhausted, the light output would drop to such a low level
(if there's any remaining light output at all), that the user would
probably immediately turn of the light, thereby protecting the cells
from damage.

In my portable CD players that use only a single AA cell, there's
little risk in using NiMH cells, and that's what I generally use.
But in CD players that use at least two AA cells, if the player uses
even a very small amount of current when powered off, NiMH cells can
be damaged if they go for many weeks or months unattended. If the
cells are recharged soon after going dead there's probably nothing
to worry about. But if you catch it too late, there's a very good
change that damage will occur. This may not be immediately
realized, however since the damaged cells can usually still be
charged, but they may have lost a considerable amount of capacity.
If the CD player can then play for another 15 hours instead of the
normal 40 hours per charge, most people may go for a *long* time
(many charge cycles) before noticing that anything is amiss. These
damaged cells may also be rejected by *some* smart chargers, even
though they are not entirely useless. Out of several smart
chargers, I only have one that can be counted on to be able to
charge these slightly damaged NiMH cells.

As for the "newer hi-powered flashlights" that Nick mentioned, the
only ones I'm aware of that use rechargeable batteries are models
used by police, firemen, military, etc., and they tend to use
proprietary NiCad or NiMH battery packs, not Li-Ion, and are usually
very expensive, costing several hundreds of dollars. That's not to
say that there aren't any Li-Ion models, but I haven't seen them.
What Nick may be thinking of are the multiple watt, *very* bright
LED lights that are designed to use non-rechargeable lithium
batteries. And it's not that they need to use lithium batteries, as
several manufacturers are now making high powered LED lights that
use alkaline batteries. The best ones use voltage regulators, so
that even as the alkaline battery voltages drop, the light output
doesn't fall off. I got one of the new MagLites about 6 months ago
and its output is today just as bright as they day I put the
batteries in it. These D cell batteries were removed from another
device because for it, the battery voltage was getting very low.

"Bob Salomon" wrote in message
...
In article 6c780d1b9c253@uwe,
"William Hathaway via PhotoKB.com" u15201@uwe wrote:

Hi Paul

Remember NiMH batteries will
self discharge at 40% per month.

No, some types of the latest NiMh AA cells come fully charged and will
hold their charge for up to a year without use or recharging.

Ansmann makes some cells that do this that are NiMh. Some companies
maxes a similar claim for AA cells that are not NiMh. Panasonic, for
instance.

--
To reply no_ HPMarketing Corp.

I saw a Pop Photo avert for these "Enerloop" batteries by Sanyo a few months
back. I guess Rayovac also has these slow self discharge NiMH batteries. The
quick self discharge problem is the only thing keeping me from adopting to
them. Any major retailer carrying them yet?
-S

"SimonLW" writes:
I saw a Pop Photo avert for these "Enerloop" batteries by Sanyo a
few months back. I guess Rayovac also has these slow self discharge
NiMH batteries. The quick self discharge problem is the only thing
keeping me from adopting to them. Any major retailer carrying them
yet?

Ritz Camera has Eneloop.

On Thu, 18 Jan 2007 13:48:36 -0500, SimonLW wrote:

I saw a Pop Photo avert for these "Enerloop" batteries by Sanyo a few months
back. I guess Rayovac also has these slow self discharge NiMH batteries. The
quick self discharge problem is the only thing keeping me from adopting to
them. Any major retailer carrying them yet?

They're available from several sources. I think that Walmart and
Ritz have been mentioned here before as having Eneloops. For
several months Circuit City has been selling Eneloops as well as
RayOVac's version, which they call Hybrid batteries. I've been
using both brands, and so far so good.

To reply no_ HPMarketing Corp.

I saw a Pop Photo avert for these "Enerloop" batteries by Sanyo a few months
back. I guess Rayovac also has these slow self discharge NiMH batteries. The
quick self discharge problem is the only thing keeping me from adopting to
them. Any major retailer carrying them yet?
-S

Ritz camera and Circuit City

ASAAR wrote:
On Thu, 18 Jan 2007 16:16:50 GMT, Paul Heslop wrote:

All my standard flashlights (torches)have NIMH batteries. The newer
hi-powered flashlights are supposed to use li-ion batteries. I also use
NIMH batteries in my portable radios, clocks, CD players, automatic lawn
sprinkler system, home automatic heating/air conditioning thermostat,
and just about anywhere alkaline batteries are called for. Exception
would be where the manufacturer states NIMH batteries should not be
used. I once read that notice for an article I bought but now I can't
remember what that article was.

I don't think I have ever seen that notice on anything, but then again
I might have just binned the instructions :O)

I also have never seen that notice, and as far as I can tell it's
because the primary reason would be to avoid using NiMH cells in
situations where they could easily become damaged, or where with
some poorly designed electronic devices, the rapid voltage drop that
occurs when one or two cells go flat could cause the loss of memory,
such as radio presets, configuration settings in mp3 players, etc.

Mag Lite flashlights specifically don't recommend the use of
rechargeable batteries. I think part of the reason is that a NiMH
cell starts off at 1.4V (at best) or maybe 1.3V a day after being
charged. A fresh alkaline cell starts off at 1.6V. A light on a
fresh set of alkalines will be brighter as a result. These are not
high-drain devices where NiMH is more efficient.

The bulbs might also be designed with the internal resistance of
alkalines in mind to maximize life. Just a thought. I've heard of
some older camera flashes that would die when NiMH batteries
were used because they were designed to use the internal resistance
of alkalines as a current limiter.

I have a Petzl LED headlamp, and the instructions state that
NiMH rechargeables are acceptable. I'll almost always recharge
them quickly before cell reversal can happen.

Fortunately, many digital electronic devices will power off before
battery damage can occur, but as I said, there are some devices
where this doesn't hold true. For those, the normally higher cost
of using alkaline batteries can be lower than NiMH batteries that
become damaged after only a small number of charge cycles.

I used NiMH AAAs in a Mag Lite Solitaire. Bad idea. It didn't mean
cell reversal but constantly deep discharging the battery when the
cap turned on in my pocket killed the capacity quickly.

Using NiMH batteries in analog devices can often be very bad for
the life of the batteries, since they'll usually continue drawing a
significant current long after one or more cells become depleted.
With flashlights that use filament bulbs, the main danger would be
if they were used unattended, such as letting a camp lantern stay on
overnight. But in normal use, as soon as the first NiMH cell
becomes exhausted, the light output would drop to such a low level
(if there's any remaining light output at all), that the user would
probably immediately turn of the light, thereby protecting the cells
from damage.

Low battery warning and/or protection diodes would help. That
would require circuitry that would cost too much for the average
flashlight.

As for the "newer hi-powered flashlights" that Nick mentioned, the
only ones I'm aware of that use rechargeable batteries are models
used by police, firemen, military, etc., and they tend to use
proprietary NiCad or NiMH battery packs, not Li-Ion, and are usually
very expensive, costing several hundreds of dollars. That's not to
say that there aren't any Li-Ion models, but I haven't seen them.
What Nick may be thinking of are the multiple watt, *very* bright
LED lights that are designed to use non-rechargeable lithium
batteries. And it's not that they need to use lithium batteries, as
several manufacturers are now making high powered LED lights that
use alkaline batteries. The best ones use voltage regulators, so
that even as the alkaline battery voltages drop, the light output
doesn't fall off. I got one of the new MagLites about 6 months ago
and its output is today just as bright as they day I put the
batteries in it. These D cell batteries were removed from another
device because for it, the battery voltage was getting very low.

Anything that expensive probably uses protection circuits to keep
the batteries from cell reversal or deep discharge. Many have low
battery indicators. Frankly it's a better idea because they can be
topped off every night with a reasonable expectation of charge life.
That would compare with alkaline cells that are left in until they run
out, and without having a good idea how much battery life is there.
Of course there could be something like a regular schedule where
alkalines are replaced every other day, but that's rather wasteful.

Paul Heslop writes:

Exception
would be where the manufacturer states NIMH batteries should not be
used. I once read that notice for an article I bought but now I can't
remember what that article was.

I don't think I have ever seen that notice on anything, but then again
I might have just binned the instructions :O)

I've seen it in two places: electronic flashes and handheld radio
battery packs. In both cases, it's because NiCd and NiMH cells have
much lower internal resistance, and thus can deliver much more current
into a low-resistance load, than alkalines can.

If you short an alkaline cell, you'll get a few amps of current flowing -
enough to make the cell get warm but not much more. If you short an AA
NiCd cell, the current may be 10 amps or more. This is enough to damage
the cell internally, melt smaller-gauge wire, and if it continues the
cell may heat up rapidly enough to explode.

Many handheld radio transmitters are powered by battery packs containing
NiCd or NiMH cells, and they always include a fuse or circuit breaker of
some sort to protect the pack from exploding or catching fire if the
terminals are accidentally shorted. Some manufacturers also sell AA
battery packs for emergencies, and these packs are usually just a
battery holder without any protective devices. The manufacturer's
manual says to use alkalines only, because alkalines are safe without
external circuit breakers. NiMH cells will fit fine and work well, but
there is a fire hazard when you do it.

In the case of electronic flashes, there were once some flashes that
depended on the battery internal resistance to limit the battery current
during flash recharge. If you installed NiCd cells instead of alkalines
(this was a long time ago), the current increased beyond the limits of
the electronics, and the flash died.

Dave

nick c wrote:
Paul Heslop wrote:
Pebble wrote:
Thanks Paul,
Still don't know if they are swappable though? My camera for
instance takes alkaline OR NIMH, it mentions in the manual . Of
course I use NIMH because the alkaline batteries send you broke.
What I meant was if a radio, torch etc doesn't mention in the manual
about using NIMH, just gives info like "insert 2 AA Alkaline
batteries as shown in the diagram below" can NIMH be used in place of
them?

I think usually they recommend alkaline due to its having a long
lasting effect, plus if I remember it rightly when they drain they
don't ooze that gunk all over, so for torches etc they are much better
than the old style battery. I am not sure that NIMH would last as long
in a standard device as an alkaline but as long as you don't mix and
match they should be fine.


All my standard flashlights (torches)have NIMH batteries. The newer
hi-powered flashlights are supposed to use li-ion batteries. I also use
NIMH batteries in my portable radios, clocks, CD players, automatic lawn
sprinkler system, home automatic heating/air conditioning thermostat,
and just about anywhere alkaline batteries are called for. Exception
would be where the manufacturer states NIMH batteries should not be
used. I once read that notice for an article I bought but now I can't
remember what that article was.

Some poorly designed (read that CHEAP) devices use the internal
resistance in the Alkaline batteries as a limiter of the current the
circuitry can draw. Using NIMH batteries in such a device might cause
damage to the device, (and to the user)!
Use of NIMH batteries in more complex, and well-designed, devices is
usually preferable to alkaline batteries due to cost factors.
Generally, using the batteries recommended by the device manufacturer is
the best choice. NIMH batteries, most of which have high values of
'self-discharge' aren't generally good candidates for devices which
aren't used often, or which are used continuously over long periods
(clocks).
Unless you really like changing batteries, and charging them, I don't
recommend NIMH batteries for clocks, thermostats, or flashlights
(torches). Multi-cell devices without electronic shutoff can cause
reverse polarity in NIMH batteries, damaging the battery.

Chargers recommended by the battery manufacturer are usually the best
choice. Either a trickle charger, or a smart charger than charges each
battery separately are best.