I've got this old Norelco T6000 Beard Trimmer, designed as a throw-away,
that I've been nursing from year to year by soldering in new batteries.
I fear I'm down to my last solder, expect something to break, rendering
the unit unusable (given my modest skills).

Looks like a AA, Amazon has specs at 600mAh and 1.2V.

What is the best and most-long-lived battery I can buy for such a unit? I
assume there are some differences judging from the price range ($4 to $15).

Have been looking for a good replacement for the unit for years, seen
nothing the least bit impressive. "They don't make 'em like they
used to!"

Thx,
P

"Law Without Equity Is No Law At All. It Is A Form Of Jungle Rule."

In article ,
Puddin' Man Pudding Dot Man At Gmail Dot Com wrote:

Looks like a AA, Amazon has specs at 600mAh and 1.2V.

What is the best and most-long-lived battery I can buy for such a unit? I
assume there are some differences judging from the price range ($4 to $15).

I recently bought a 2-AA-cell pack for this purpose from Mouser...
part number 6396-1K-F2 / CM1T-AA1000. It uses 1000 mAh NiCd cells,
and cost $5.95 plus shipping.

You could easily get more than twice that capacity by using NiMH cells
or a pack thereof, but if the charge-control circuit in the shaver is
designed for NiCd it might not work all that well with NiMH (might
over- or under-charge the battery, shorten its life, etc.).

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

"Dave Platt" wrote in message
...
In article ,
Puddin' Man Pudding Dot Man At Gmail Dot Com wrote:

Looks like a AA, Amazon has specs at 600mAh and 1.2V.

What is the best and most-long-lived battery I can buy for such a unit? I
assume there are some differences judging from the price range ($4 to
$15).

I recently bought a 2-AA-cell pack for this purpose from Mouser...
part number 6396-1K-F2 / CM1T-AA1000. It uses 1000 mAh NiCd cells,
and cost $5.95 plus shipping.

You could easily get more than twice that capacity by using NiMH cells
or a pack thereof, but if the charge-control circuit in the shaver is
designed for NiCd it might not work all that well with NiMH (might
over- or under-charge the battery, shorten its life, etc.).

Probably not. The Norelco "charger" is probably little more than a resistor
in series with the power supply. A NiMH should have no trouble with that.

Why not get some NiMH cells with tabs from Thomas Distributing? The ones I
used in my Polaroid #365 electronic flash work fine, and the #363 rapid
charger -- designed for nicads -- shuts off properly.

On Sat, 6 Aug 2011 08:00:20 -0700, "William Sommerwerck"
wrote:

You could easily get more than twice that capacity by using NiMH cells
or a pack thereof, but if the charge-control circuit in the shaver is
designed for NiCd it might not work all that well with NiMH (might
over- or under-charge the battery, shorten its life, etc.).

Probably not. The Norelco "charger" is probably little more than a resistor
in series with the power supply. A NiMH should have no trouble with that.

Why not get some NiMH cells with tabs from Thomas Distributing? The ones I
used in my Polaroid #365 electronic flash work fine, and the #363 rapid
charger -- designed for nicads -- shuts off properly.

Hmmmmmmm. I peruse
http://www.streetdirectory.com/trave...vs_li_ion.html
and it sez longer (than NiMh) life cycles for NiCd.

If true, I'd likely be better off with NiCd. No?

If the life cycle of 1.2v NiCd rechargables is appreciably variable, what is the
best NiCd I can buy? Brand or mnfgr or ? with the longest life cycle??

Thx,
P

"Law Without Equity Is No Law At All. It Is A Form Of Jungle Rule."

Nicads are obsolescent, if not actually obsolete. If you can find NiMH cells
that fit, use them.

I've been listening to my Sony Discman at work. It runs on two AA cells. I
use PowerEx (MAHA) 2700mAh NiMH cells. In two weeks, I've gone through 16
disks of Bach organ works, seven of Hermann Baumann playing valveless horn,
and I'm well into an Andras Schiff collection -- and they're still running
strong.

"Puddin' Man"

Hmmmmmmm. I peruse
http://www.streetdirectory.com/trave...vs_li_ion.html


** FFS - get some real information.


and it sez longer (than NiMh) life cycles for NiCd.


** Absolute nonsense.

The number of cycles quoted by makers is a complete fantasy that has almost
nothing to do with any real life application.

Wiki quotes 2000 cycles for NiCd, but gives no source for that mad claim.

IME, treat NiCd or NiMH cells with great care and you can expect a few
hundred cycles - do anything careless ( overcharge or overheat) and you
can ruin them in one day.



..... Phil

On Sun, 7 Aug 2011 08:40:34 +1000, "Phil Allison"
wrote:


"Puddin' Man"

Hmmmmmmm. I peruse
http://www.streetdirectory.com/trave...vs_li_ion.html


** FFS - get some real information.


and it sez longer (than NiMh) life cycles for NiCd.


** Absolute nonsense.

The number of cycles quoted by makers is a complete fantasy that has almost
nothing to do with any real life application.

Wiki quotes 2000 cycles for NiCd, but gives no source for that mad claim.

IME, treat NiCd or NiMH cells with great care and you can expect a few
hundred cycles - do anything careless ( overcharge or overheat) and you
can ruin them in one day.



.... Phil


I'm using 1000mAh NiMH AA cells from Poundworld, sold in packs of 2
(everything £1, kinda like a 5 and dime) GPB). I'm very happy with
them for TV remotes, wireless keyboard / mice, 80's vintage CBM
calculator and even a hair trmmer. 2 AA cells for 1GPB. As almost
everything has $1 = £1 exchange rate should be able to find some for
about 1$ in USA.

At that price the key issue is how easy it is to rebuild the device
you are putting them in.
--
Peter Hill
Spamtrap reply domain as per NNTP-Posting-Host in header
Can of worms - what every fisherman wants.
Can of worms - what every PC owner gets!

"Peter Hill"

I'm using 1000mAh NiMH AA cells from Poundworld, sold in packs of 2
(everything £1, kinda like a 5 and dime) GPB). I'm very happy with
them for TV remotes, wireless keyboard / mice, 80's vintage CBM
calculator ..


** The man is totally insane.

Wonder if he uses any of his NiMh cells for what they are good at.



..... Phil

In article ,
William Sommerwerck wrote:

You could easily get more than twice that capacity by using NiMH cells
or a pack thereof, but if the charge-control circuit in the shaver is
designed for NiCd it might not work all that well with NiMH (might
over- or under-charge the battery, shorten its life, etc.).

Probably not. The Norelco "charger" is probably little more than a resistor
in series with the power supply. A NiMH should have no trouble with that.

As I understand it, the problem with this approach is the question of
shutting off the charge when the battery is full. NiMH cells are less
tolerant of being overcharged than NiCd, and are best used with a
charger that has a somewhat more sensitive full-charge detector (e.g.
zero-delta-V and/or direct temperature sense, rather than negative-
delta-V as was often used with NiCd cells.


--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Dave Platt wrote:
As I understand it, the problem with this approach is the question of
shutting off the charge when the battery is full. NiMH cells are less
tolerant of being overcharged than NiCd, and are best used with a
charger that has a somewhat more sensitive full-charge detector (e.g.
zero-delta-V and/or direct temperature sense, rather than negative-
delta-V as was often used with NiCd cells.

It's slightly more complicated, if you replace NiCad cells in a battery
pack with a temperature sensor, you have to replace the sensor too. NiMH
cells have a much lower "cook temperature" than NiCads.

The other night I was having trouble sleeping and read a very nice article
about modifying Motorola NiCad chargers to properly (and not over) charge
NiMH packs. Since it was late at night, I remember the main points and
that I read it, but not where. :-)

Geoff.

--
Geoffrey S. Mendelson N3OWJ/4X1GM
Making your enemy reliant on software you support is the best revenge.

On Mon, 8 Aug 2011 19:19:04 +0000 (UTC), "Geoffrey S. Mendelson"
wrote:

I remember the main points and
that I read it, but not where. :-)

http://www.repeater-builder.com/motorola/genesis/nimh-charger-mod.html
These simplistic chargers are horrible and will kill any battery fed
to it in short order. There are some similar Kenwood chargers with
the same problem. They tend to overcharge, even after the battery
pack gets over-heated. I've modified a few of these with good results
as the author describes.



--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

"William Sommerwerck" wrote:
Nicads are obsolescent, if not actually obsolete. If you can find NiMH cells
that fit, use them.

I've been listening to my Sony Discman at work. It runs on two AA cells. I
use PowerEx (MAHA) 2700mAh NiMH cells. In two weeks, I've gone through 16
disks of Bach organ works, seven of Hermann Baumann playing valveless horn,
and I'm well into an Andras Schiff collection -- and they're still running
strong.

Depending on current draw, nicads will deliver more current due to lower
impedance. For motors that can be a problem.

Greg

Jeff Liebermann wrote in
:

On Mon, 8 Aug 2011 19:19:04 +0000 (UTC), "Geoffrey S. Mendelson"
wrote:

I remember the main points and
that I read it, but not where. :-)

http://www.repeater-builder.com/motorola/genesis/nimh-charger-mod.html
These simplistic chargers are horrible and will kill any battery fed
to it in short order. There are some similar Kenwood chargers with
the same problem. They tend to overcharge, even after the battery
pack gets over-heated. I've modified a few of these with good results
as the author describes.




I've read that charge terminating NiMH by temperature rise is not good or
proper,that it has to be done by voltage monitoring.
By the time the NiMH cells heat up,the damage has been done.

--
Jim Yanik
jyanik
at
localnet
dot com

In article ,
Jim Yanik wrote:

http://www.repeater-builder.com/motorola/genesis/nimh-charger-mod.html
These simplistic chargers are horrible and will kill any battery fed
to it in short order. There are some similar Kenwood chargers with
the same problem. They tend to overcharge, even after the battery
pack gets over-heated. I've modified a few of these with good results
as the author describes.




I've read that charge terminating NiMH by temperature rise is not good or
proper,that it has to be done by voltage monitoring.
By the time the NiMH cells heat up,the damage has been done.

I believe that they're both aspects of the same phenomenon... that is,
the change in the cell's terminal voltage is the result of the rise in
temperature, which itself results from the fact that the energy being
pumped in is now being converted to heat rather than to
electrochemical potential.

In effect, sensing the terminal voltage and shutting down when it
ceases to rise is a faster way of detecting the rise in the cell's
internal temperature. You don't have to wait for the heat to "soak
out" of the cell and warm up the thermistor.

The recommendations I've read suggest that the best shutdown approach
for NiMH cells is via zero-delta-V measurement, with a temperature
sensor as a secondary, and a timer as a last-ditch shutoff.

The temperature sensor is best used to detect "sudden rise in
temperature" rather than "specific temperature threshold". This makes
the detection less sensitive to variations in the room temperature,
and also to the sort of variation in thermistor values written about
in the document Jeff pointed us to. This is probably best done with a
microcontroller or a dedicated charge-control IC that can perform
time-based measurement analysis.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

"gregz"


Depending on current draw, nicads will deliver more current due to lower
impedance. For motors that can be a problem.


** Simply not true.

AA cells in NiCd or NiMH have closely similar impedances and hence max
current outputs.

The figure is between 10 and 20 milliohms in both cases.


..... Phil

Probably not. The Norelco "charger" is probably little more than a
resistor
in series with the power supply. A NiMH should have no trouble with that.

As I understand it, the problem with this approach is the question of
shutting off the charge when the battery is full. NiMH cells are less
tolerant of being overcharged than NiCd, and are best used with a
charger that has a somewhat more sensitive full-charge detector (e.g.
zero-delta-V and/or direct temperature sense, rather than negative-
delta-V as was often used with NiCd cells.

This isn't a problem if you're charging at a fairly low rate. A good-quality
cell -- nicad or NiMH -- will tolerate an indefinite low ("trickle") charge.

If the resistor is chosen to give a 0.1C charge rate when the cell is at
about 1V, the charge rate when the cell has "fully" charged will be rather
lower ("depending").

It's only in the past decade or so that rapid-charging with auto-cutoff has
become commonplace. Prior to that, almost every nicad device was charged
with a simple series resistor. And guess what? It worked.

As I said earlier, I have a Polaroid #365 electronic flash with NiMH cells
that replaced the original nicads. The #363 rapid charger has no trouble
stopping and switching to trickle charge. It was designed almost 45 years
ago.

I've read that charge terminating NiMH by temperature rise is
not good or proper, that it has to be done by voltage monitoring.
By the time the NiMH cells heat up, the damage has been done.

Based on what I learned at Microsoft Hardware, this is not true. "Hitting"
the NiMH cell "hard", to the point where it significantly heats the cell,
supposedly gives a deeper charge.

I've have NiMHs get quite warm -- even hot -- in chargers. If one such
occurrence ruined the cell, then most of my cells would be useless. None is.

"gregz" wrote in message
...
"William Sommerwerck" wrote:

Nicads are obsolescent, if not actually obsolete. If you can find NiMH
cells
that fit, use them.

I've been listening to my Sony Discman at work. It runs on two AA cells.
I
use PowerEx (MAHA) 2700mAh NiMH cells. In two weeks, I've gone through 16
disks of Bach organ works, seven of Hermann Baumann playing valveless
horn,
and I'm well into an Andras Schiff collection -- and they're still
running
strong.

Depending on current draw, nicads will deliver more current due to lower
impedance. For motors that can be a problem.

Not in a circuit that regulates the current flow to the motor. Which, of
course, CD players have.

The only case I know of where what you say is true, is the use of nicads in
really cheap electronic flashes. These were designed so that the higher
internal resistance of alkaline cells would limit the current flow. With
nicads, they can overheat and be damaged.

"Phil Allison" wrote:
"Puddin' Man"

Hmmmmmmm. I peruse
http://www.streetdirectory.com/trave...vs_li_ion.html


** FFS - get some real information.


and it sez longer (than NiMh) life cycles for NiCd.


** Absolute nonsense.

The number of cycles quoted by makers is a complete fantasy that has almost
nothing to do with any real life application.

Wiki quotes 2000 cycles for NiCd, but gives no source for that mad claim.

IME, treat NiCd or NiMH cells with great care and you can expect a few
hundred cycles - do anything careless ( overcharge or overheat) and you
can ruin them in one day.



.... Phil

I had a bunch of NiMH cells laying around for a few years, they just did
not work anymore.

From using them in model cars and Dustbusters, etc, the general idea 10
years ago was the nicads had lower impedance, but in reading further,
today's NiMH cell are better Z wise.

Still got some 50 year old German nicad packs that still work.

Greg

"gregz" wrote in message
...

Got some 50 year old German nicad packs that still work.

Ah, German precision...

William Sommerwerck wrote:
Probably not. The Norelco "charger" is probably little more than a
resistor
in series with the power supply. A NiMH should have no trouble with that.

As I understand it, the problem with this approach is the question of
shutting off the charge when the battery is full. NiMH cells are less
tolerant of being overcharged than NiCd, and are best used with a
charger that has a somewhat more sensitive full-charge detector (e.g.
zero-delta-V and/or direct temperature sense, rather than negative-
delta-V as was often used with NiCd cells.

This isn't a problem if you're charging at a fairly low rate. A good-quality
cell -- nicad or NiMH -- will tolerate an indefinite low ("trickle") charge.

I'd like to see a reference that supports that.

NiCd batteries are very tolerant of trickle charging.
Early NiMH cells were very INTOLERANT of trickle charging.
Lots has changed over the years. Maybe they're better now,
but I'd like to see some vendor info on that.



If the resistor is chosen to give a 0.1C charge rate when the cell is at
about 1V, the charge rate when the cell has "fully" charged will be rather
lower ("depending").

It's only in the past decade or so that rapid-charging with auto-cutoff has
become commonplace. Prior to that, almost every nicad device was charged
with a simple series resistor. And guess what? It worked.

Here's some empirical evidence.
Power tools have historically had three charge modes.
The cheapest have a trickle charger. People leave 'em on charge all the
time.
The "better" tools have a fast charger with a thermal coutout. The cell
gets HOT and the charge is terminated by the thermal cutout.

The "best" tools have a fast charger that often measures -deltaV for NiCds
or 0delatV for NiMH.

So, here's the experiment.

Go to a garage sale. Almost every garage sale has at least one battery
powered drill.
Have you EVER found a battery powered drill at a garage sale that had a
good battery? I haven't.

As I said earlier, I have a Polaroid #365 electronic flash with NiMH cells
that replaced the original nicads. The #363 rapid charger has no trouble
stopping and switching to trickle charge. It was designed almost 45 years
ago..

The bottom line is that you should always use the EXACT battery chemistry,
type, model number with the charger designed exactly for that battery.

If you're willing to reverse-engineer the charging circuit, you can often
use alternative cells.
Or you can redesign the charger to match the cells.
Or you can just get lucky with any random selection.
I've been lucky 99+% of the time. But I have also been unlucky.
One day I'll find the rest of the battery pack that exploded
when the lawnmower throws it thru a window.
YMMV

"mike" wrote in message
...

Here's some empirical evidence.
Power tools have historically had three charge modes.
The cheapest have a trickle charger. People leave 'em on charge all the
time.
The "better" tools have a fast charger with a thermal coutout. The cell
gets HOT and the charge is terminated by the thermal cutout.

The "best" tools have a fast charger that often measures -deltaV for NiCds
or 0delatV for NiMH.

So, here's the experiment.

Go to a garage sale. Almost every garage sale has at least one battery
powered drill.
Have you EVER found a battery powered drill at a garage sale that had a
good battery? I haven't.

If it had a good battery, it wouldn't be at the garage sale.

ba-DUM!


As I said earlier, I have a Polaroid #365 electronic flash with NiMH
cells
that replaced the original nicads. The #363 rapid charger has no trouble
stopping and switching to trickle charge. It was designed almost 45 years
ago..

The bottom line is that you should always use the EXACT battery chemistry,
type, model number with the charger designed exactly for that battery.

That's no longer possible.

NiMH "behavior" is "close-enough" to nicad that replacement often works
well.

William Sommerwerck wrote:
"mike" wrote in message
...

Here's some empirical evidence.
Power tools have historically had three charge modes.
The cheapest have a trickle charger. People leave 'em on charge all the
time.
The "better" tools have a fast charger with a thermal coutout. The cell
gets HOT and the charge is terminated by the thermal cutout.

The "best" tools have a fast charger that often measures -deltaV for NiCds
or 0delatV for NiMH.

So, here's the experiment.

Go to a garage sale. Almost every garage sale has at least one battery
powered drill.
Have you EVER found a battery powered drill at a garage sale that had a
good battery? I haven't.

If it had a good battery, it wouldn't be at the garage sale.

ba-DUM!

You're letting your desire to be right overshadow your analysis.
How many battery powered drills does the average family need?
When every other garage sale has one, two or even three dead
drills, the statistics are hard to ignore.
The drills are rarely dead. It's almost always the batteries.

Take a design that was intended to be the cheapest initial
purchase cost based on the crappiest batteries available at the time.
Replace the cells with ones having 5x the capacity.
Now, even if the charger design was proper, fast charge termination
is unlikely to be anywhere near correct...as in "never terminates".

Sure, it often works. You feeling lucky?



As I said earlier, I have a Polaroid #365 electronic flash with NiMH
cells
that replaced the original nicads. The #363 rapid charger has no trouble
stopping and switching to trickle charge. It was designed almost 45 years
ago..

The bottom line is that you should always use the EXACT battery chemistry,
type, model number with the charger designed exactly for that battery.

That's no longer possible.

NiMH "behavior" is "close-enough" to nicad that replacement

often

I'm in complete agreement. The only thing we seem to differ on is the
consequences of when it DOESN'T work and if those consequences
are acceptable.


works
well.

"William Sommerwerck"


Got some 50 year old German nicad packs that still work.

Ah, German precision...



** Nah - probably Jewish and too terrified to stop.





..... Phil

"mike" wrote in message
...

You're letting your desire to be right overshadow your analysis.
How many battery powered drills does the average family need?
When every other garage sale has one, two or even three dead
drills, the statistics are hard to ignore.
The drills are rarely dead. It's almost always the batteries.

Take a design that was intended to be the cheapest initial
purchase cost based on the crappiest batteries available at the time.
Replace the cells with ones having 5x the capacity.
Now, even if the charger design was proper, fast charge termination
is unlikely to be anywhere near correct...as in "never terminates".

Sure, it often works. You feeling lucky?

"Well, do ya, punk?"

Not that many years ago I bought a Ryobi drill at Home Despot. It had a
conventional, non-rapid-charging charger. The battery died (in my view)
prematurely, and (violating Federal law) Ryobi could not supply a
replacement pack. So I bought a new drill (a Ryobi with a modular pack). Had
a replacement been available, I'd probably still be using the original.

Your correct observation about the average family rarely needing more than
one cordless drill only confirms my point.

You missed the point I was making -- rapid chargers almost always have some
form of auto cutoff. The kind of charging I was talking about (which I made
perfectly clear) was the "resistor-in-series-with-the-power-supply" type.
This is not a rapid-charge -- though it does charge faster than when the
cell voltage is lower. Such a system works fairly well -- eg, a Dust Buster.
I've gotten a good 200 recharges on my Model 5000, because I let the cells
run down before recharging, and I don't leave the unit on the charger all
the time.


NiMH "behavior" is "close-enough" to nicad that replacement
[often] works well.

I'm in complete agreement. The only thing we seem to differ on is the
consequences of when it DOESN'T work and if those consequences
are acceptable.

I completely agree with your complete agreement. The confusion occurred
because you misread me. I do not advocate rapid charging of any kind of cell
without a "fool-proof" shutoff system. I'm surprised at how far my MAHA
C9000 pushes NiMH cells. I keep an eye on it, and sometimes terminate the
charge cycle manually, because the cell has gotten warmer than I like, even
though the cell voltage is above 1.4 volts. I'm so cautious, I rarely charge
faster than 0.3C, though MAHA and other NiMH manufacturers recommend as high
as 0.5C.

I have had good luck with LSD NiMH, like the Sanyo Eneloop for use in
cameras and two way radio gear.

"Steve Stone" wrote in message
...

I have had good luck with LSD NiMH, like the Sanyo Eneloop
for use in cameras and two-way-radio gear.

Do you use them when you go on trips?

On Sun, 14 Aug 2011 02:18:37 -0700, mike wrote:

This isn't a problem if you're charging at a fairly low rate. A good-quality
cell -- nicad or NiMH -- will tolerate an indefinite low ("trickle") charge.

I'd like to see a reference that supports that.

http://batteryuniversity.com/learn/article/charging_nickel_metal_hydride
"It is difficult, if not impossible, to slow-charge a NiMH
battery. At a C-rate of 0.1 to 0.3C, the voltage and temperature
profiles fail to exhibit defined characteristics to measure the
full-charge state accurately and the charger must depend on a
timer. Harmful overcharge will occur if a fixed timer controls the
charge. This is especially apparent when charging partially or
fully charged batteries."
Not exactly what you wanted, but a good reason why a "trickle" or
"maintaining" charge doesn't really work.

NiCd batteries are very tolerant of trickle charging.

Nope. I've successfully killed NiCd batteries in (Jedi series) radio
chargers that produce a 0.1c "maintaining" charge when fully charged.
After about a year of continuous charging at 0.1c, the batteries were
all dead. That's what happened to the local hospital emergency
network. The county issued MT2000 radios and chargers to all the
hospitals in the county. In case of emergency, they could all
communicate with each other through a repeater or directly. Once a
week, there was a test to make sure things were working. No problems
for 3 years until I decided to check the batteries. I found a mix of
NiCd and NiMH batteries. All that I tested were dead. The radios
would work for about 2 minutes, which was just long enough for the
test but not long enough for useful operation. Since the batteries
were never discharged, I concluded that the 0.1c maintaining charge
was the culprit.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

"Jeff Liebermann" wrote in message
...
On Sun, 14 Aug 2011 02:18:37 -0700, mike wrote:

This isn't a problem if you're charging at a fairly low rate. A
good-quality
cell -- nicad or NiMH -- will tolerate an indefinite low ("trickle")
charge.

I'd like to see a reference that supports that.

http://batteryuniversity.com/learn/article/charging_nickel_metal_hydride
"It is difficult, if not impossible, to slow-charge a NiMH
battery. At a C-rate of 0.1 to 0.3C, the voltage and temperature
profiles fail to exhibit defined characteristics to measure the
full-charge state accurately and the charger must depend on a
timer. Harmful overcharge will occur if a fixed timer controls the
charge. This is especially apparent when charging partially or
fully charged batteries."
Not exactly what you wanted, but a good reason why a "trickle" or
"maintaining" charge doesn't really work.

If that's true (and I assume it is), it's the first really significant
difference between nicads and NiMHs I've heard of.

It also explains why my C9000 charger doesn't shut off when I charge at
"only" 0.3. Guess I'll have to change the way I charge."

\
NiCd batteries are very tolerant of trickle charging.

Nope. I've successfully killed NiCd batteries in (Jedi series) radio
chargers that produce a 0.1c "maintaining" charge when fully charged.
After about a year of continuous charging at 0.1c, the batteries were
all dead. That's what happened to the local hospital emergency
network. The county issued MT2000 radios and chargers to all the
hospitals in the county. In case of emergency, they could all
communicate with each other through a repeater or directly. Once a
week, there was a test to make sure things were working. No problems
for 3 years until I decided to check the batteries. I found a mix of
NiCd and NiMH batteries. All that I tested were dead. The radios
would work for about 2 minutes, which was just long enough for the
test but not long enough for useful operation. Since the batteries
were never discharged, I concluded that the 0.1C maintaining charge
was the culprit.

I stand corrected. HOWEVER... No one would consider 0.1C a trickle charge,
as it has traditionally been the "standard" charge for regular nicad cells.

It's also possible this might have been a memory effect.

"William Sommer******"

"Steve Stone"

I have had good luck with LSD NiMH, like the Sanyo Eneloop
for use in cameras and two-way-radio gear.

Do you use them when you go on trips?


** Let him who is without sin cast the first Stone ...

Tim is turning in his grave...




..... Phil

Jeff Liebermann wrote in
:

On Sun, 14 Aug 2011 02:18:37 -0700, mike wrote:

This isn't a problem if you're charging at a fairly low rate. A
good-quality cell -- nicad or NiMH -- will tolerate an indefinite
low ("trickle") charge.

I'd like to see a reference that supports that.

http://batteryuniversity.com/learn/a...l_metal_hydrid
e
"It is difficult, if not impossible, to slow-charge a NiMH
battery. At a C-rate of 0.1 to 0.3C, the voltage and temperature
profiles fail to exhibit defined characteristics to measure the
full-charge state accurately and the charger must depend on a
timer. Harmful overcharge will occur if a fixed timer controls the
charge. This is especially apparent when charging partially or
fully charged batteries."
Not exactly what you wanted, but a good reason why a "trickle" or
"maintaining" charge doesn't really work.

NiCd batteries are very tolerant of trickle charging.

Nope. I've successfully killed NiCd batteries in (Jedi series) radio
chargers that produce a 0.1c "maintaining" charge when fully charged.
After about a year of continuous charging at 0.1c, the batteries were
all dead. That's what happened to the local hospital emergency
network. The county issued MT2000 radios and chargers to all the
hospitals in the county. In case of emergency, they could all
communicate with each other through a repeater or directly. Once a
week, there was a test to make sure things were working. No problems
for 3 years until I decided to check the batteries. I found a mix of
NiCd and NiMH batteries. All that I tested were dead. The radios
would work for about 2 minutes, which was just long enough for the
test but not long enough for useful operation. Since the batteries
were never discharged, I concluded that the 0.1c maintaining charge
was the culprit.


OTOH,the B&D Dustbuster I had was designed to stay on the charger when not
in use,and it lasted 10 years before I had to have another NiCd pack
installed. that new pack lasted almost as long.
I've seen NiCds listed at DigiKey specifically intended for staying on the
trickle charger when not in use.

--
Jim Yanik
jyanik
at
localnet
dot com

On Sun, 14 Aug 2011 08:34:04 -0700, "William Sommerwerck"
wrote:

If that's true (and I assume it is), it's the first really significant
difference between nicads and NiMHs I've heard of.

I must admit that I didn't know that either. I had always assumed the
NiCd and NiMH cells were interchangeable in chargers. I guess not.

It also explains why my C9000 charger doesn't shut off when I charge at
"only" 0.3. Guess I'll have to change the way I charge."

I've been playing with charging individual cells at 5C or higher.
Works fine as long as you know exactly how long to charge, condition
of the cell, and ambient temp. From experience, the battery does NOT
get hot until it's overcharged.

I stand corrected. HOWEVER... No one would consider 0.1C a trickle charge,
as it has traditionally been the "standard" charge for regular nicad cells.

I didn't say trickle charge. According to Motorola, it's a
"maintaining" charge, whatever that means. I agree that a trickle
charge would be much less. However, my experience is that you cannot
charge a NiCd battery with anything less than about 0.05C. It just
never comes to full charge. I don't know what causes this effect and
don't want to go Googling for references right now.

It's also possible this might have been a memory effect.

There's no such thing as NiCd memory effect unless you're talking
about space qualified batteries.
http://en.wikipedia.org/wiki/Memory_effect
I have yet to see data, numbers, and reproduceable tests that
demonstrate memory effect. What I have seen are problems with
electrolyte loss, caused by overcharging and subsequent venting, that
mimick the problem. Incidentally, I found this by carefully weighing
the better before and after overcharging. It's not much loss, but
it's always present.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Sun, 14 Aug 2011 10:58:33 -0500, Jim Yanik
wrote:

OTOH,the B&D Dustbuster I had was designed to stay on the charger when not
in use,and it lasted 10 years before I had to have another NiCd pack
installed. that new pack lasted almost as long.

My Dustbuster battery died after about 2 years of sitting on permanent
charge. I didn't investigate. I installed a home made battery pack
about a year ago. Works fine. I think the original batteries may
have had a problem.

I've seen NiCds listed at DigiKey specifically intended for staying on the
trickle charger when not in use.

Never heard of such a thing, but I'll look.

What creates the problem is that many vendor rate their drills,
laptops, and devices by how long it will run on battery power. In
order to improve their numbers, they try to cram as much charge into
the battery as possible. That works well enough with a new battery,
but as the battery gets older, the table driven and timer charge
controllers start to overcharge. That causes heating, which is an
invitation to a premature demise of the battery.

In my never humble opinion, there's only one correct way to charge
batteries, and that's with a "coulomb counting" charge controller. It
measures the current in, runs tests on battery capacity, and adjust
the charge current and timing as necessary. They can programmed for
almost any desired attribute (long battery life, fast charging,
conservative capacity, etc), and will compensate for battery aging.
Many of the charge controller chips made for LiIon will work for NiMH.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

"Jeff Liebermann" wrote in message
news
I have yet to see data, numbers, and reproduceable tests that
demonstrate memory effect. What I have seen are problems with
electrolyte loss, caused by overcharging and subsequent venting, that
mimick the problem. Incidentally, I found this by carefully weighing
the better before and after overcharging. It's not much loss, but
it's always present.

Reports on "memory effect" go back almost 50 years to the introduction of
cordless toothbrushes, which were commonly used briefly before being
recharged. They would (supposedly) lose capacity.

Then people whose toothbrushes were accidentally activated in their luggage
and thoroughly run down recovered most of their capacity (the toothbrushes,
not the people). GE supposedly discovered the cause of memory effect
(electrode crystallization), but no cells that addressed the problem were
ever manufactured, that I know of.

"Jeff Liebermann" wrote in message
...

In my never humble opinion, there's only one correct way to charge
batteries, and that's with a "coulomb counting" charge controller. It
measures the current in, runs tests on battery capacity, and adjust
the charge current and timing as necessary. They can programmed for
almost any desired attribute (long battery life, fast charging,
conservative capacity, etc), and will compensate for battery aging.
Many of the charge controller chips made for LiIon will work for NiMH.

You might like the MAHA C9000.

Puddin' Man wrote:
On Sat, 6 Aug 2011 08:00:20 -0700, "William Sommerwerck"
wrote:

You could easily get more than twice that capacity by using NiMH
cells or a pack thereof, but if the charge-control circuit in the
shaver is designed for NiCd it might not work all that well with
NiMH (might over- or under-charge the battery, shorten its life,
etc.).

Probably not. The Norelco "charger" is probably little more than a
resistor in series with the power supply. A NiMH should have no
trouble with that.

Why not get some NiMH cells with tabs from Thomas Distributing? The
ones I used in my Polaroid #365 electronic flash work fine, and the
#363 rapid charger -- designed for nicads -- shuts off properly.

Hmmmmmmm. I peruse
http://www.streetdirectory.com/trave...vs_li_ion.html
and it sez longer (than NiMh) life cycles for NiCd.

If true, I'd likely be better off with NiCd. No?

It says NiMH has larger capacity, but NiCd has longer run time. You say what?

"Bob Fool"

Hmmmmmmm. I peruse
http://www.streetdirectory.com/trave...vs_li_ion.html
and it sez longer (than NiMh) life cycles for NiCd.

If true, I'd likely be better off with NiCd. No?

It says NiMH has larger capacity, but NiCd has longer run time.


** That is a very obvious error.



.... Phil

On Mon, 15 Aug 2011 07:17:32 -0700, "Bob F"
wrote:

Hmmmmmmm. I peruse
http://www.streetdirectory.com/trave...vs_li_ion.html
and it sez longer (than NiMh) life cycles for NiCd.

I'm always suspicious of information sites that don't bother to supply
any numbers. This looks like a more useful comparison:
http://www.ka7oei.com/nicds.html
If you want authoritative reading, start he
http://batteryuniversity.com

If true, I'd likely be better off with NiCd. No?

You decide. It's not so much the chemistry, as it is how it's used.
See below.

It says NiMH has larger capacity, but NiCd has longer run time. You say what?

NiCd can handle more charge cycles. For NiCd, is you do everything
right you'll get perhaps 1000 charge cycles before the battery
deteriorates to about half capacity. For NiMH, you'll get perhaps 600
charge cycles.

Doing the math for typical batteries, NiCd will deliver:
0.7A-hr * 1000 cycles = 700A-hr
while NiMH will deliver:
2.0A-hr * 600 cycles = 1200A-hr
So, if you recycle your batteries when they're half dead, you'll get
almost twice the lifetime with a NiMH than with NiCd, where you need
to charge NiMH about 40% less often.

However, that's at best, under ideal conditions, with a device that
favors NiMH (i.e. no self-discharge problems and moderately high peak
current). If you do something non-ideal, such as charge the batteries
every day at the same time, you'll get 1000 days out of the NiCd and
600 days out of the NiMH which makes the NiCd the winner. NiMH is the
superior technology only if you charge the batteries when they're
almost fully discharged (at the knee in the discharge curve). If you
recharge by the clock, then NiCd is better because you can recharge it
more often.




--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Sun, 14 Aug 2011 11:54:12 -0700, "William Sommerwerck"
wrote:

"Jeff Liebermann" wrote in message
news
I have yet to see data, numbers, and reproduceable tests that
demonstrate memory effect. What I have seen are problems with
electrolyte loss, caused by overcharging and subsequent venting, that
mimick the problem. Incidentally, I found this by carefully weighing
the better before and after overcharging. It's not much loss, but
it's always present.

Reports on "memory effect" go back almost 50 years to the introduction of
cordless toothbrushes, which were commonly used briefly before being
recharged. They would (supposedly) lose capacity.

I don't know about electric tooth brushes, but I've had far too much
entertainment from 2way radio handhelds (HT's), pagers, cellphones,
and Norelco rechargeable shavers. The various radios and pagers were
all originally NiCd's and would tend to kill batteries far earlier
than my calculations would suggest. It didn't take long to find out
why. All of them overcharged in some manner. Most commonly, the
charge cycle was terminated by a timer that was based on the
characteristics of a brand new battery. That was fine for a new
radio, but would consistently overcharge (and overhead) an older
battery. An important clue is that a battery only overheats when over
charged. The brand new batteries would rarely get warm. The older
batteries would get rather hot.

Keeping my Norelco shaver batteries alive was an adventure. It stated
when I bought a used (cheap) cordless shaver at a garage sale. I
replace the batteries (Sub-C NiCd with new cells and noticed that the
shaver was warm after charging. After about a year, the batteries
were dead and I had only charged it perhaps 20 times. Some
measurements found that the charge controller was simply a fixed
resistor running at about 0.2C. There was no end of charge circuit,
and it would just continue overcharging. I later found a 950RX
shaver, which I use erratically today, that has an LCD bar graph to
indicate state of charge. Surely this shaver has an end of charge
detector. Nope. 0.2C at any charge level. I killed a set of
batteries after 2 years, which I guess is an improvement.

My experiences with power tools (mostly older Makita) is a mix. I
tend to do better with NiCd batteries because I have more of them and
because I tend to charge before every use. The greater number of
charge cycles of NiCd makes it a winner over NiMH.

Then people whose toothbrushes were accidentally activated in their luggage
and thoroughly run down recovered most of their capacity (the toothbrushes,
not the people). GE supposedly discovered the cause of memory effect
(electrode crystallization), but no cells that addressed the problem were
ever manufactured, that I know of.

If my rapidly failing memory serves me correctly, NiCd was going out
of fashion because of concerned over Cadmium in the water supply and
that NiMH was the recommended ecologically correct replacement.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 8/14/2011 10:23 AM, William Sommerwerck wrote:
"Steve wrote in message
...

I have had good luck with LSD NiMH, like the Sanyo Eneloop
for use in cameras and two-way-radio gear.

Do you use them when you go on trips?


Yes