Wall Warts

[Jeff Liebermann]

On Thu, 26 May 2011 12:51:48 -0500, Puddin' Man
<puddingDOTman@gmail.com> wrote:

The + side measures 3 ohms.

Ok. There may be a diode inside the base. Try reversing the leads on
the ohms-guesser and see if it acts like a diode.

Measures infinite ohms when reversed.

It's a diode, with no series resistor. That presents a problem.
Without some form of current limiting, the voltage of the xformer will
need to be VERY carefully controlled to keep from overcharging the
battery. I will swear there's a resistor or charge controller
somewhere in the system, but I can't tell where from here.

I'm 'fraid you'll have to elaborate on this last. And, what is "C" in
.1C?

Sorry. C is the current rating of the battery in ampere-hours. A
typical NiCd pack, full of AA cells will have a rating of about 750
ma-hr. NiMH would be around 1200 to 2200 ma-hr. The maximum charge
current of the charger should be about 0.1 times this value (i.e. 10%)
or 75ma for the NiCd pack.

Of course, make sure you don't have a shorted
battery pack.

So I gotta crack the battery pack open. And test each cell individually?
How?

You don't need to destroy the battery pack in order to test it. First,
just measure the terminal voltage of the battery pack after it's been
sitting around for a day without being charged. Even if totally
discharged, it should have at least 1.1 volts per cell or about 7.7VDC
across the terminals. A fully charged NiCd will have about 1.45VDC
per cell or about 10.2VDC across the terminals.

Now, if you really want to test you battery packs, I have a West Mtn
Radio CBA-IIv1:
<http://www.westmountainradio.com/product_info.php?products_id=cba3>



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

 

[Puddin' Man]

On Fri, 27 May 2011 17:37:46 -0700, Jeff Liebermann <jeffl@cruzio.com> wrote:

On Thu, 26 May 2011 12:51:48 -0500, Puddin' Man
puddingDOTman@gmail.com> wrote:


The + side measures 3 ohms.

Ok. There may be a diode inside the base. Try reversing the leads on
the ohms-guesser and see if it acts like a diode.

Measures infinite ohms when reversed.

It's a diode, with no series resistor. That presents a problem.
Without some form of current limiting, the voltage of the xformer will
need to be VERY carefully controlled to keep from overcharging the
battery. I will swear there's a resistor or charge controller
somewhere in the system, but I can't tell where from here.

I dunno where it would be ...

I'm 'fraid you'll have to elaborate on this last. And, what is "C" in
.1C?

Sorry. C is the current rating of the battery in ampere-hours. A
typical NiCd pack, full of AA cells will have a rating of about 750
ma-hr. NiMH would be around 1200 to 2200 ma-hr. The maximum charge
current of the charger should be about 0.1 times this value (i.e. 10%)
or 75ma for the NiCd pack.

Thanks.

Of course, make sure you don't have a shorted
battery pack.

So I gotta crack the battery pack open. And test each cell individually?
How?

You don't need to destroy the battery pack in order to test it.

Good!

First,
just measure the terminal voltage of the battery pack after it's been
sitting around for a day without being charged. Even if totally
discharged, it should have at least 1.1 volts per cell or about 7.7VDC
across the terminals. A fully charged NiCd will have about 1.45VDC
per cell or about 10.2VDC across the terminals.

I measure just under 4vdc for the pack. Your opinion is
solicited.

Now, if you really want to test you battery packs, I have a West Mtn
Radio CBA-IIv1:
http://www.westmountainradio.com/product_info.php?products_id=cba3

Only $150-300. Lordy mercy!

I rambled thru my WW box again and found the following:

ATLINKS USA
Telephone power supply
Input: AC120V 60hz 4.4w
Output: DC 9v 200 mA
Class 2 transformer
UL etc

but when I measure, I get about 20vdc from my meter.
Any idea why the drastic difference from spec?

Thx,
P

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

 

[Jim Yanik]

Jeff Liebermann <jeffl@cruzio.com> wrote in
news:2ag0u6hqsttr5ri4j5ogvgkosj7ihhlseu@4ax.com:

On Thu, 26 May 2011 12:51:48 -0500, Puddin' Man
puddingDOTman@gmail.com> wrote:


The + side measures 3 ohms.

Ok. There may be a diode inside the base. Try reversing the leads on
the ohms-guesser and see if it acts like a diode.

Measures infinite ohms when reversed.

It's a diode, with no series resistor. That presents a problem.
Without some form of current limiting, the voltage of the xformer will
need to be VERY carefully controlled to keep from overcharging the
battery. I will swear there's a resistor or charge controller
somewhere in the system, but I can't tell where from here.

the internal impedance of the transformer itself may be the current
limiter. That's the way it was in a B&D VersaPack NiCd charger I have.

I'm 'fraid you'll have to elaborate on this last. And, what is "C" in
.1C?

Sorry. C is the current rating of the battery in ampere-hours. A
typical NiCd pack, full of AA cells will have a rating of about 750
ma-hr. NiMH would be around 1200 to 2200 ma-hr.

Just a FYI,I have some Everready NiMH AA cells rated at 2350 mAH(bought at
Wal-Mart),and saw some no-name 2800 mAH AA cells for sale on Ebay.


--
Jim Yanik
jyanik
at
localnet
dot com

 

[Jeff Liebermann]

On Fri, 27 May 2011 22:10:49 -0500, Puddin' Man
<puddingDOTman@gmail.com> wrote:

First,
just measure the terminal voltage of the battery pack after it's been
sitting around for a day without being charged. Even if totally
discharged, it should have at least 1.1 volts per cell or about 7.7VDC
across the terminals. A fully charged NiCd will have about 1.45VDC
per cell or about 10.2VDC across the terminals.

I measure just under 4vdc for the pack. Your opinion is
solicited.

Your battery pack is dead, kaput, eWaste, gone, shorted, etc. That's
what probably killed the wall wart and inspired the recall. Charging
a shorted cell is a great way to overheat an unprotected transformer.
If you simply replace the transformer, you're likely to fry it again.

Now, if you really want to test you battery packs, I have a West Mtn
Radio CBA-IIv1:
http://www.westmountainradio.com/product_info.php?products_id=cba3

Only $150-300. Lordy mercy!

The requisite computer is not included in the price. I use it to
characterize Li-Ion mutations for model airplanes, robotics, cell
phones, and general havoc. The energy available is basically the area
under the discharge curve.

ATLINKS USA
Telephone power supply
Input: AC120V 60hz 4.4w
Output: DC 9v 200 mA
Class 2 transformer
UL etc

but when I measure, I get about 20vdc from my meter.
Any idea why the drastic difference from spec?

Sure. You're measuring the voltage without a load. If you load the
xformer with a 200ma load:
R = 9V / 0.2A = 45 ohms (47 ohms is close enough)
and
Power = E*I = 9v * 0.2A = 1.8 Watts (so use 5 watt resistor)
you should get around 9V DC.



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

 

[Jeff Liebermann]

On Sat, 28 May 2011 15:38:14 -0500, Jim Yanik <jyanik@abuse.gov>
wrote:

Jeff Liebermann <jeffl@cruzio.com> wrote in
news:2ag0u6hqsttr5ri4j5ogvgkosj7ihhlseu@4ax.com:
Sorry. C is the current rating of the battery in ampere-hours. A
typical NiCd pack, full of AA cells will have a rating of about 750
ma-hr. NiMH would be around 1200 to 2200 ma-hr.

Just a FYI,I have some Everready NiMH AA cells rated at 2350 mAH(bought at
Wal-Mart),and saw some no-name 2800 mAH AA cells for sale on Ebay.

Amazing. I've run tests on some 2200 ma-hr NiMH AA cells using my
CBA-II
<http://www.westmountainradio.com/product_info.php?products_id=cba3>
The results are not very impressive. If I discharge at rediculously
low rates, such as 0.01C, I might be able to squeeze 2200 ma-hr out of
a cell. I tested one at about twice the estimated self discharge
rate, and calculated about 5000 ma-hr out of the cell. I think it
took about a week to finish the test. However, when I ran it at a
more realistic load of 2C, I was barely able to squeeze out 1000
ma-hr. This was also for a brand new cell, as repeated
charge/discharge cycles would also decrease the cell capacity.

See the discharge curves at:
<http://4gdo.com/batfaq.htm#Question%20#4:>
Note how the area under the curve decreases with increasing load.

I keep planning to post some test results, but never seem to have the
time to organize anything. Sorry(tm).

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

 

[William Sommerwerck]

"Geoffrey S. Mendelson" <gsm@mendelson.com> wrote in message
news:slrniu4nnd.fpd.gsm@cable.mendelson.com...

Jeff Liebermann wrote:

This was also for a brand new cell, as repeated
charge/discharge cycles would also decrease the cell capacity.

Funny, I've always read the opposite with NiMH cells. They need
to go through several charge/discharge cycles before they reach
full capacity.

This has always been the "conventional wisdom" about nicads, as well.

I wish I knew what the "truth" about rechargeables was. Contrary to the
common belief, I've never had problems with rapid self-discharge with NiMHs.

 

[Jeff Liebermann]

On Sun, 29 May 2011 14:59:03 +0000 (UTC), "Geoffrey S. Mendelson"
<gsm@mendelson.com> wrote:

Jeff Liebermann wrote:
This was also for a brand new cell, as repeated
charge/discharge cycles would also decrease the cell capacity.

Funny, I've always read the opposite with Nimh cells, they need to go through
several charge/discharge cycles before they reach full capacity.

I've never seen that. Nothing similar found with Google or on my
favorite sites:
<http://en.wikipedia.org/wiki/Nickel-metal_hydride_battery>
<http://batteryuniversity.com>
<http://batteryuniversity.com/learn/article/Nickel_based_batteries>

Where I have seen something like this is with cheap Chinese laptop
battery packs. The problem is not the battery. It's the charge
controller inside the battery. It has to be run up and down in
voltage and "trained" before it knows how the pack is going to act.
This is usually done at the factory by reputable battery pack
manufacturers, but seems to be avoided by others. I've personally
only seen this with Li-Ion battery packs, but am told that it's also a
problem with older chemistries.

This is especially true of the long discharge ones, which come "pre-charged"
at about 80% and then at least in my experience take 5-10 cycles to come
up to a useable capacity. It also seems in my experience that the lower the
charge rate, the more cycles a cell needs.

That's probably because NiMH has a rather high self-discharge rate.
They may have been at 100% when they left the factory, but have
self-discharged in the box. Also, the ideal storage charge level is
about 40% for NiMH. None of the NiMH batteries I've tested (Duracell,
Rayovac, Sanyo, Energizer, various no-name, and various OEM) have
showed anything other than a slow loss of capacity (area under the
curve) for repeated charge/discharge cycles.

BTW, if you have any info on charging an Azden HT, please let me know.

No experience. This might help if it uses NiMH:
<http://batteryuniversity.com/learn/article/charging_nickel_metal_hydride>

Note that most of my experiments have been on single cells, not
battery packs.


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

 

[Jeff Liebermann]

On Sat, 28 May 2011 15:38:14 -0500, Jim Yanik <jyanik@abuse.gov>
wrote:

Just a FYI,I have some Everready NiMH AA cells rated at 2350 mAH(bought at
Wal-Mart),and saw some no-name 2800 mAH AA cells for sale on Ebay.

Argh. I haven't been paying attention.
Duracell 2650 2650 ma-hr
Energizer e2 2500 ma-hr
Maha Powerex AA 2700 ma-hr
Maybe I'll do some shopping and testing (timer permitting).

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

 

[Jeff Liebermann]

On Sun, 29 May 2011 07:46:08 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

Amazing. I've run tests on some 2200 ma-hr NiMH AA cells using my
CBA-II
http://www.westmountainradio.com/product_info.php?products_id=cba3

Here's some result from the RC groups on NiMH packs.
<http://www.rcgroups.com/forums/attachment.php?attachmentid=642246>
At 0.5A discharge rate, various manufacturers yielded 1700 to 2000
ma-hr.

At 0.25A, this Sanyo battery pack managed to squeeze out 1275 ma-hr:
<http://www.rcgroups.com/forums/attachment.php?attachmentid=2330249>

More of the same for 1900 ma-hr:
<http://www.rcgroups.com/forums/attachment.php?attachmentid=2328003>

This is somewhat better than what I was getting.

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

 

[Geoffrey S. Mendelson]

Jeff Liebermann wrote:

This was also for a brand new cell, as repeated
charge/discharge cycles would also decrease the cell capacity.

Funny, I've always read the opposite with Nimh cells, they need to go through
several charge/discharge cycles before they reach full capacity.

This is especially true of the long discharge ones, which come "pre-charged"
at about 80% and then at least in my experience take 5-10 cycles to come
up to a useable capacity. It also seems in my experience that the lower the
charge rate, the more cycles a cell needs.

BTW, if you have any info on charging an Azden HT, please let me know.

Thanks,

Geoff.

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

 

[Puddin' Man]

Many thanks.

S'long,
P

On Sun, 29 May 2011 07:29:38 -0700, Jeff Liebermann <jeffl@cruzio.com> wrote:

On Fri, 27 May 2011 22:10:49 -0500, Puddin' Man
puddingDOTman@gmail.com> wrote:

First,
just measure the terminal voltage of the battery pack after it's been
sitting around for a day without being charged. Even if totally
discharged, it should have at least 1.1 volts per cell or about 7.7VDC
across the terminals. A fully charged NiCd will have about 1.45VDC
per cell or about 10.2VDC across the terminals.

I measure just under 4vdc for the pack. Your opinion is
solicited.

Your battery pack is dead, kaput, eWaste, gone, shorted, etc. That's
what probably killed the wall wart and inspired the recall. Charging
a shorted cell is a great way to overheat an unprotected transformer.
If you simply replace the transformer, you're likely to fry it again.

Now, if you really want to test you battery packs, I have a West Mtn
Radio CBA-IIv1:
http://www.westmountainradio.com/product_info.php?products_id=cba3

Only $150-300. Lordy mercy!

The requisite computer is not included in the price. I use it to
characterize Li-Ion mutations for model airplanes, robotics, cell
phones, and general havoc. The energy available is basically the area
under the discharge curve.

ATLINKS USA
Telephone power supply
Input: AC120V 60hz 4.4w
Output: DC 9v 200 mA
Class 2 transformer
UL etc

but when I measure, I get about 20vdc from my meter.
Any idea why the drastic difference from spec?

Sure. You're measuring the voltage without a load. If you load the
xformer with a 200ma load:
R = 9V / 0.2A = 45 ohms (47 ohms is close enough)
and
Power = E*I = 9v * 0.2A = 1.8 Watts (so use 5 watt resistor)
you should get around 9V DC.

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

 

[Dave Platt]

In article <e3m4u6pu8i5cdkdb8m8jb228u2ghh4ortl@4ax.com>,
Jeff Liebermann <jeffl@cruzio.com> wrote:

Amazing. I've run tests on some 2200 ma-hr NiMH AA cells using my
CBA-II
http://www.westmountainradio.com/product_info.php?products_id=cba3
The results are not very impressive. If I discharge at rediculously
low rates, such as 0.01C, I might be able to squeeze 2200 ma-hr out of
a cell. I tested one at about twice the estimated self discharge
rate, and calculated about 5000 ma-hr out of the cell. I think it
took about a week to finish the test. However, when I ran it at a
more realistic load of 2C, I was barely able to squeeze out 1000
ma-hr.

Most NiMH/NiCd battery manufacturers seem to rate their cells at a
discharge rate of 0.05C (20 hour rate) - that would be around 100 mA
for those AA cells. Sanyo's charts for their "Eneloop" show
about a 10% reduction in useful capacity at a discharge rate of 0.5C
(1000 mA).

If you're actually pulling over 4 amps from them (2C discharge rate)
I'd expect a significant further loss of capacity.

For comparison, the same Sanyo charts seem to show that an alkaline
battery loses about 75% of its useful capacity when you go from 100 mA
rates to 1000 mA rates.

I gather that the loss of useful capacity is due in part to the series
resistance of the battery, and in part due to inefficiencies in the
chemistry under high rates of discharge.

This was also for a brand new cell, as repeated
charge/discharge cycles would also decrease the cell capacity.

Had these cells been "formed" properly prior to your test (via several
slow-charge / slow-discharge cycles)? There seems to be a general
agreement that NiMH cells don't achieve their maximum storage capacity
unless they've gone through several cycles like this, and that many
manufacturers don't take the time to do this during the manufacturing
process. I've seen some indication of this in my own testing (using a
smart-charger which can cycle the batteries and report the capacities
for each cycle).

--
Dave Platt <dplatt@radagast.org> 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]

Argh. I haven't been paying attention.
Duracell 2650 2650 ma-hr
Energizer e2 2500 ma-hr
Maha Powerex AA 2700 ma-hr
Maybe I'll do some shopping and testing (timer permitting).

There seems to be a real tradeoff. In general, the very-high-
capacity NiMH cells seem to have a more rapid rate of self-discharge;
they're good for "use immediately after charge" applications, but not
so good for "charge and store" standby uses.

The low-self-discharge cells (e.g. Sanyo Eneloop, PowerEx Imedion, and
similar) seem to run around 10% lower in rated capacity.

For comparison, the Maha Powerex AA are rated at 2700 mAh, while the
Maha Powerex "Imedion" AA are rated at 2400 mAh.

I've read that this is due to difference the structure/alloy of the
metal hydride used for the electrodes... varities which can bind more
hydrogen, also tend to suffer from more spontaneous de-binding and
leakage (or so my crude understanding goes... I probably have the
details wrong).

I've had reasonably good results with the Imedion and Eleloop types
for my radio go-kit... I can charge them up after use, and depend on
finding plenty of power available even six months later. Never could
do that with standard NiMH types, when I tried a few years ago... I
couldn't trust them to be useful even 3 months after charging.

--
Dave Platt <dplatt@radagast.org> 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!

 

[William Sommerwerck]

"Dave Platt" <dplatt@radagast.org> wrote in message
news:u24db8-8sg.ln1@radagast.org...

Had these cells been "formed" properly prior to your test (via several
slow-charge / slow-discharge cycles)? There seems to be a general
agreement that NiMH cells don't achieve their maximum storage capacity
unless they've gone through several cycles like this, and that many
manufacturers don't take the time to do this during the manufacturing
process.

Why should they, when it would add to the cells' cost? Given the relatively
low price of uP-controlleed chargers, there's no point.

 

[William Sommerwerck]

"Dave Platt" <dplatt@radagast.org> wrote in message
news:1l4db8-8sg.ln1@radagast.org...

There seems to be a real tradeoff. In general, the very-high-
capacity NiMH cells seem to have a more rapid rate of self-discharge;
they're good for "use immediately after charge" applications, but not
so good for "charge and store" standby uses.

That hasn't been my experience. My 2200mAh and 2700mAh MAHAs hold up very
well -- months, in fact. I've never made a study of the actual capacity, but
they /do not/ "fall flat" shortly after being put into use.

 

[Jeff Liebermann]

On Mon, 30 May 2011 11:26:06 -0700, dplatt@radagast.org (Dave Platt)
wrote:

This was also for a brand new cell, as repeated
charge/discharge cycles would also decrease the cell capacity.

Had these cells been "formed" properly prior to your test (via several
slow-charge / slow-discharge cycles)?

Nope. They came directly out of the box. I didn't record how long
they had been sitting on the shelf. I must admit my ritual was rather
sloppy.

I would initially charge the battery in a Radio Shock 23-1305 charger.
<http://www.buzzillions.com/reviews/radio-shack-30-minute-battery-charger-4-aa-aaa-batteries-reviews>
Not the best, but I have 3 of them, so they get used. One big
advantage for me is that it will independently charge a single AA
cell. Also, it runs off 12VDC. It came with 4ea NiMH cells, but I
killed them long ago.

After charging, I would leave the battery sit for anywhere between 1
and 8 hrs to let it cool down and supply sufficient time to charge up
more cells. I vaguely recall that they were Sanyo cells, but as I
have several types on the bench, I can't tell which one was used.

I would then connect the battery to the CBA-II tester, plug in the
desired test settings, and generate a graph. Repeat for several
cells. I would usually try to discharge it until the "knee" is
visible, which my guess(tm) is down to about 15% of capacity.

I haven't done much NiMH testing (mostly because Li-Ion is my current
interest), but I do recall seeing a drop in capacity with every cycle.
There was no evidence of any "conditioning" effects. Incidentally,
until I see numerical or personal evidence of such a "conditioning"
requirement for NiMH batteries, I prefer to ignore it. To me, it's
the same as NiCd "memory effect", which I have yet to experience, and
which I have spent considerable time attempting to demonstrate.
<http://en.wikipedia.org/wiki/Memory_effect>

There seems to be a general
agreement that NiMH cells don't achieve their maximum storage capacity
unless they've gone through several cycles like this,

I'll believe it when I see it demonstrated, documented, or chemically
explained. I just wasted some time searching Google Scholar for any
references to NiMH conditioning, training, pre-charging, etc. Zilch.

and that many
manufacturers don't take the time to do this during the manufacturing
process. I've seen some indication of this in my own testing (using a
smart-charger which can cycle the batteries and report the capacities
for each cycle).

I was watching some TV show (How it's made???) showing how batteries
are manufactured. "Testing" the batteries was done on a high speed
conveyor and lasted about 1/2 second per cell. I don't think this is
enough time to "condition" the battery.

As far as I have been able to guess (Yeah, I know, I should have
measured), the typical NiMH cell arrives out of the box at about 30%
charge. I don't know if this is intentional, an artifact of the
manufacturing process, or some safety requirement. There are quite a
few battery vendors proclaiming that they ship NiMH and other
batteries discharged for safety reasons. Anyway, if they ship them
discharged, then the "conditioning" cycle would need to be:
Full -> discharge -> Full again -> test -> discharge
I wouldn't expect such an exercise for consumer products.






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

 

[Jeff Liebermann]

On Mon, 30 May 2011 11:35:45 -0700, dplatt@radagast.org (Dave Platt)
wrote:

Argh. I haven't been paying attention.
Duracell 2650 2650 ma-hr
Energizer e2 2500 ma-hr
Maha Powerex AA 2700 ma-hr
Maybe I'll do some shopping and testing (timer permitting).

There seems to be a real tradeoff. In general, the very-high-
capacity NiMH cells seem to have a more rapid rate of self-discharge;
they're good for "use immediately after charge" applications, but not
so good for "charge and store" standby uses.

The low-self-discharge cells (e.g. Sanyo Eneloop, PowerEx Imedion, and
similar) seem to run around 10% lower in rated capacity.

Sanyo Eneloop.
<http://www.eneloop.info/home/performance-details/capacity.html>
<http://www.costco.com/Browse/Product.aspx?Prodid=11504514>
<http://www.eneloop.info/fileadmin/EDITORS/ENELOOP/DATA_SHEETS/HR-3UTGA_data_sheet.pdf>
<http://www.rcgroups.com/forums/showthread.php?t=630534>

LSD doesn't have lower capacity. It's roughly the same as other NiMH.
LSD NiMH batteries have a higher terminal voltage. The energy
capacity is the area under the discharge curve, which is close to
identical for types with the same chemistry. However, the higher
terminal voltage will cause the curve to drop earlier for the LSD
NiMH, so they appear to not last as long.

Lots of vendors of LSD batteries:
<http://en.wikipedia.org/wiki/Low_self-discharge_NiMH_battery>

I've read that this is due to difference the structure/alloy of the
metal hydride used for the electrodes... varities which can bind more
hydrogen, also tend to suffer from more spontaneous de-binding and
leakage (or so my crude understanding goes... I probably have the
details wrong).

Dunno. I've read some on battery chemistry, but have generally
ignored NiMH as a marginal idea. Sorry(tm).

I've had reasonably good results with the Imedion and Eleloop types
for my radio go-kit... I can charge them up after use, and depend on
finding plenty of power available even six months later. Never could
do that with standard NiMH types, when I tried a few years ago... I
couldn't trust them to be useful even 3 months after charging.

Are you running an electric airplane, using the battery pack to run a
glow plug, igniting a squib, or running telemetry electronics? All
would benefit from a switch to Li-Ion.

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

 

[Jeff Liebermann]

On Mon, 30 May 2011 12:02:45 -0700, "William Sommerwerck"
<grizzledgeezer@comcast.net> wrote:

"Dave Platt" <dplatt@radagast.org> wrote in message
news:1l4db8-8sg.ln1@radagast.org...

There seems to be a real tradeoff. In general, the very-high-
capacity NiMH cells seem to have a more rapid rate of self-discharge;
they're good for "use immediately after charge" applications, but not
so good for "charge and store" standby uses.

That hasn't been my experience. My 2200mAh and 2700mAh MAHAs hold up very
well -- months, in fact. I've never made a study of the actual capacity, but
they /do not/ "fall flat" shortly after being put into use.

The reason I bought a CBA-II battery tester was because of my
inability to properly guess actual battery capacity.

Most of my experience with NiMH batteries was with Metricom radios and
various Motorola and Kenwood handheld radios. It doesn't take much to
kill them. For example, you don't even need to discharge them to a
NiMH battery pack. The country distributed Motorola MTS2000 radios to
all the hospitals as part of the HEARNET (Hospital Emergency
Administrative Radio Network) system. The radios were permanently
planted in charger with power on 24x7. Some radios were turned on,
but most were left off. There would be a short test roughly twice per
month. After about a years, not one of the radios were functional
because all the NiMH batteries were dead.

I'm having a similar experience in my palatial office, where I use a
Motorola HT600 and several NTN7016A NiMH battery packs. Unlike the
hospital example, I make it a point of not leaving the battery in the
charger after it reaches full charge. I also use the radio in a
normal manner, charging the battery only when the xmitter craps out.
The result is that I charge the battery approximately 3 times per
week. Despite this care, I manage to kill about one battery every 2
years (that's after only about 150 charge cycles).

I also use NiMH batteries in my various cameras (Canon S5IS etc) all
of which use AA cells. I'm seeing the typical 1%/day self-discharge
rate. I keep two sets of batteries in the bag. It's not unusual for
me to find the spares to be nearly dead after about 2 months.

Your NiMH milage may vary, but mine sucks.

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

 

[William Sommerwerck]

"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:a4u7u69f03pb04a2o3j3jjbdh9msv9r4ih@4ax.com...

I also use NiMH batteries in my various cameras (Canon S5IS etc) all
of which use AA cells. I'm seeing the typical 1%/day self-discharge
rate. I keep two sets of batteries in the bag. It's not unusual for
me to find the spares to be nearly dead after about 2 months.

Your NiMH milage may vary, but mine sucks.

Weird. Which brands do you use? I use mostly MAHA (PowerEx).

 

[Dave Platt]

In article <9is7u6pk6r7l5c1meqlcftvnua85klo6rs@4ax.com>,
Jeff Liebermann <jeffl@cruzio.com> wrote:

Sanyo Eneloop.
http://www.eneloop.info/home/performance-details/capacity.html
http://www.costco.com/Browse/Product.aspx?Prodid=11504514
http://www.eneloop.info/fileadmin/EDITORS/ENELOOP/DATA_SHEETS/HR-3UTGA_data_sheet.pdf
http://www.rcgroups.com/forums/showthread.php?t=630534

LSD doesn't have lower capacity. It's roughly the same as other NiMH.

Interesting... one of Sanyo's pages shows different results. See

http://www.eneloop.info/home/performance-details/capacity.html

They compare alkaline, Sanyo Eneloop, and the Sanyo "high capacity"
NiMH cells. The latter have a definite advantage in capacity, and the
terminal voltages under load look almost identical in the "100 mA
discharge" graph.

LSD NiMH batteries have a higher terminal voltage. The energy
capacity is the area under the discharge curve, which is close to
identical for types with the same chemistry. However, the higher
terminal voltage will cause the curve to drop earlier for the LSD
NiMH, so they appear to not last as long.

Hmmm... the graphs on the page cited above seem to suggest
differently... what do you think?

Are you running an electric airplane, using the battery pack to run a
glow plug, igniting a squib, or running telemetry electronics? All
would benefit from a switch to Li-Ion.

Nope... typical ham-radio handheld radio use (about 80% receive, 20%
transmit).

I do have several such radios which run on LiIon batteries. My
preferred "field assignment" radio is still a NiCd/NiMH type... with
the auxiliary six-AA-cell battery pack, and a bunch of charged
Imedions and some alkaline AA cells as last-ditch backup, I could be
deployed for a couple of days before I'd be in immediate need of a
recharge.

--
Dave Platt <dplatt@radagast.org> 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!