Wall Warts

[Jim Yanik]

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

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.

The Everready 2350 mAH cells I've been using for my bicycle LED headlight(2
watts draw,homemade) have been very good in regards to low self-
discharge,much better than I was led to expect.
I also have some "pre-charged" Ray-O-Vac NiMH marked at 2100 mAH that are
advertised as holding their charge much longer.


--
Jim Yanik
jyanik
at
localnet
dot com

 

[Jeff Liebermann]

On Mon, 30 May 2011 15:14:17 -0700, "William Sommerwerck"
<grizzledgeezer@comcast.net> wrote:

"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).

Yeah, I know I'm weird. I use a random assortment of whatever I
blunder across. Costco has Sanyo Eneloop, so I have a pile of those.
I just found several 4 packs of Energizer 2300ma-hr NiMH cells, so I
guess I'll use those. I have no idea what's in the camera or in the
bottom of the bag, but I'll guess is some no-name brand I picked up at
a ham radio flea market. I just found some Duracel 2050ma-hr cells.
Oh swell, a pair of Lenmar NoMem Pro 1500 ma-hr cells in my emergency
bag. Nice mess (and proud of it).

I've been running some battery tests on the new batteries for the last
4 hrs to see if I can find any "conditioning" effects. Stay tunes.


--
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

 

[josephkk]

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:

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.

I see stuff like that as well. Though i am starting to wonder if it is
just printing higher and higher numbers for the capacity without any
difference in the cells themselves.

 

[Geoffrey S. Mendelson]

josephkk wrote:

I see stuff like that as well. Though i am starting to wonder if it is
just printing higher and higher numbers for the capacity without any
difference in the cells themselves.

All I can say is that I have several AA battery cases for ham radios. The ICOM
ones take all AA batteries that I have every put in them, the one off brand one
I have that was made in the 1980's won't. It will take AA alkeline batteries
and up to 1600mah Nimh batteries, but not the 2500 ones. They really are
wider. :-(

Geoff.

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

 

[Jim Yanik]

"Geoffrey S. Mendelson" <gsm@mendelson.com> wrote in
news:slrniullab.ec7.gsm@cable.mendelson.com:

josephkk wrote:
I see stuff like that as well. Though i am starting to wonder if it
is just printing higher and higher numbers for the capacity without
any difference in the cells themselves.

All I can say is that I have several AA battery cases for ham radios.
The ICOM ones take all AA batteries that I have every put in them, the
one off brand one I have that was made in the 1980's won't. It will
take AA alkeline batteries and up to 1600mah Nimh batteries, but not
the 2500 ones. They really are wider. :-(

Geoff.

I have a Ray-O-Vac 1W LED flashlight,and alkalines fit loosely,while both
Everready and Ray-O-Vac NiMH are snug fits. almost worrisome snug.

they seem to be a tad longer,too.I had some NiMH cells in a plastic two
cell battery holder,and they had to be forced in,despite the long spring
travel of the holders,and caused the plastic to split over time.
Also,the NiMH were "fat" and the holders would not keep the cells in
place,they'd slowly creep out.

--
Jim Yanik
jyanik
at
localnet
dot com