Testing a NiMH battery charger

[D]

I have this battery charger which I use for NiMH AA cells:
http://www.eastcoastphoto.com/a/283/rapid-battery-charger-f-AACHAR.html.
Some new cells I just bought do not seem to be holding a charge very
long, and I'd like to check the output of the charger to be sure it's
functioning fully. This charger uses temp to tell when the batteries
are"full" (thermistor is present under batteries), then switches to
"trickle". How can I tell by measurement if the thing is operating
properly? I have access to a multimeter and oscilloscope for testing
purposes.

Any suggestions appreciated.

Dan

 

[Phil Allison]

"Dope"

I have this battery charger which I use for NiMH AA cells:
http://www.eastcoastphoto.com/a/283/rapid-battery-charger-f-AACHAR.html.
Some new cells I just bought do not seem to be holding a charge very long,
and I'd like to check the output of the charger to be sure it's functioning
fully. This charger uses temp to tell when the batteries are"full"
(thermistor is present under batteries), then switches to "trickle". How
can I tell by measurement if the thing is operating properly? I have
access to a multimeter and oscilloscope for testing purposes.

Any suggestions appreciated.

** Are you for real ??

The batteries get hot and you can feel that with your fingers.

Means they are charged.


...... Phil

 

[D]

"Dope"

** Are you for real ??

The batteries get hot and you can feel that with your fingers.

Means they are charged.


..... Phil

Are YOU "for real"????? Define HOT, smartass.

Idiot.

 

[D]

More like four.

Phil is an intelligent person with a lot of solid knowledge about
electronics and servicing. For reasons that no one here understands
(psychosis? bad values?) he chooses to abuse people.

In most NiMH chargers, the batteries get fairly warm -- even hot -- towards
the end of the charge. NiMH cells can tolerate heavy charging, and some
manufacturers even recommend a "hard" charge (0.5C or faster) to cram the
maximum amount of energy into them.

The chargers I own switch to trickle charge between 1.40V and 1.46V. If the
cell reads that, you can be reasonably sure it's "fully" charged.

Thanks for the helpful reply. I appreciate that the batteries increase
in temperature when they're charged, hence the thermistor, but "hot" is
pretty non-specific, I was thinking there must be some charger voltage
vs current curve which tracks the level of charge. I'll measure the
voltage right after charging & see the result. These are 2,000 mAh
cells. If nothing else, I suppose I could afix a suitable load, & see
if the do indeed put out their rated current for the period claimed.

Concerning your "friend" "Phil" with the social issues, I've been using
this NG off and on for the better part of 20 years, back to when Sam
Goldwasser was prominent (is he still around?), and I've always found
the posters to be informative & civil. I don't recall ever seeing that
kind of juvenile nonsense from anyone here before. Phil needs to get
out of his mother's basement & make some friends.

OK, "Phil", go ahead and unleash your childish, unoriginal,
seen-it-before-from-a-million-losers-like-you tirade. I have no
intention of reading it.

And for god's sake, get back on your medication.

 

[Phil Allison]

"Fucking DOPE "

Thanks for the helpful reply. I appreciate that the batteries increase in
temperature when they're charged, hence the thermistor,

** Charging is COMPLETE when the cells begin converting the charge current
into heat.

Concerning your "friend" "Phil" with the social issues, I've been using
this NG off and on for the better part of 20 years, back to when Sam
Goldwasser was prominent (is he still around?), and I've always found the
posters to be informative & civil. I don't recall ever seeing that kind of
juvenile nonsense from anyone here before.

** As anyone here can see, I posted a damn good reply to your absurdly
stupid question.

Then YOU came back with a gratuitous insult.

YOU are way beyond merely STUPID and bad tempered.

YOU are a fucking MORON and a stinking, fucking LIAR.

Just like all anonymous cunts with Hotmail addys.

FOAD ASAP.



..... Phil

 

[mike]

I have this battery charger which I use for NiMH AA cells:
http://www.eastcoastphoto.com/a/283/rapid-battery-charger-f-AACHAR.html.
Some new cells I just bought do not seem to be holding a charge very
long, and I'd like to check the output of the charger to be sure it's
functioning fully. This charger uses temp to tell when the batteries
are"full" (thermistor is present under batteries), then switches to
"trickle". How can I tell by measurement if the thing is operating
properly? I have access to a multimeter and oscilloscope for testing
purposes.

Any suggestions appreciated.

yep, be more specific.
"not very long"


NiMH batteries don't hold a charge for long.
Especially high capacity ones.
Especially cheap no-name ones.
I'd not expect more than a couple of weeks of
useful storage.
Enloops or equivalent hold a charge much longer.

Temperature charge termination is a BAD way to charge cells.
It can work well if you fully discharge before recharging.
Problem is that if you put in a nearly charged cell, you can
do damage before the cell has a chance to heat up enough to
trigger the termination.

If you mean they don't put out as much energy as expected,
that's a different issue.
Depending on the load current and the device shut-off characteristic,
internal battery resistance can cause the device to shut down long
before it's used up. Cameras are especially bad in that respect.
I've got cameras that run well on one battery vendor, but not at all
on any other.

It's like anything else. If you want long service life, buy
premium cells and chargers.

 

[D]

yep, be more specific.
"not very long"


NiMH batteries don't hold a charge for long.
Especially high capacity ones.
Especially cheap no-name ones.
I'd not expect more than a couple of weeks of
useful storage.
Enloops or equivalent hold a charge much longer.

Temperature charge termination is a BAD way to charge cells.
It can work well if you fully discharge before recharging.
Problem is that if you put in a nearly charged cell, you can
do damage before the cell has a chance to heat up enough to
trigger the termination.

If you mean they don't put out as much energy as expected,
that's a different issue.
Depending on the load current and the device shut-off characteristic,
internal battery resistance can cause the device to shut down long
before it's used up. Cameras are especially bad in that respect.
I've got cameras that run well on one battery vendor, but not at all
on any other.

It's like anything else. If you want long service life, buy
premium cells and chargers.

Mike - Thanks for the reply. I agree temperature change sensing isn't
as good as sensing voltage changes. The batteries are Harbor Freight,
so they are cheap, but I've been using these types from them in AA & AAA
for years with no issues in things like remote keyboards, lower drain
items. Bought a new set for a CAMERA, as you said. The camera does
have a setting for cell type, and a discharge function, which I've used
to deplete them completely twice with recharging. I know this is
especially an issue with cameras. Interesting about the internal
resistance.

You may be right about springing for better cells, at least in this high
drain usage. Only trouble is my $$$ is a bit limited at the moment ;-/

Dan

 

[William Sommerwerck]

NiMH batteries don't hold a charge for long.

Especially high capacity ones.

Not so. I've put AA NiMH cells in a flash, that were charged months earlier,
and they powered it well. This is an urban legend that has little basis in
fact.

Temperature-charge termination is a BAD way to charge cells.

If it's the only method of termination, yes. But it's necessary to prevent
overcharging, especially when the manufacturer recommends "slamming" the
cell.

 

[William Sommerwerck]

You may be right about springing for better cells, at least in this high-

drain usage. nly trouble is my $$$ is a bit limited at the moment.

Good cells aren't expensive. A 16-pack of 2700 mAh MAHAs at Thomas
Distributing is less than $3 per cell, and they throw in plastic cases and a
carrying case.

My experience has been that a 2700 mAh cell has about the same capacity as
25-cent Costco (Toshiba?) cell. So you need to recharge them only about 12
times before you break even. That's a good deal.

http://www.thomasdistributing.com/1...es-and-Free-Maha-Case_p_1334.html?frontpage=1

I have two of these chargers, and paid about $40 for each -- when they were
on sale. You might want to wait.

http://www.thomasdistributing.com/Maha-Powerex-MH-C9000-AA--AAA-Battery-Chargerbr_p_134.html

 

[William Sommerwerck]

Concerning your "friend" "Phil" with the social issues, I've been using

Phil was raised by Dingos, till he killed & ate them.

That's nothing. He also ate the Chamberlains' daughter.

 

[mike]

Mike - Thanks for the reply. I agree temperature change sensing isn't as
good as sensing voltage changes. The batteries are Harbor Freight, so
they are cheap, but I've been using these types from them in AA & AAA
for years with no issues in things like remote keyboards, lower drain
items. Bought a new set for a CAMERA, as you said. The camera does have
a setting for cell type, and a discharge function, which I've used to
deplete them completely twice with recharging. I know this is especially
an issue with cameras. Interesting about the internal resistance.

You may be right about springing for better cells, at least in this high
drain usage. Only trouble is my $$$ is a bit limited at the moment ;-/

Dan

If you do the research, you'll probably decide that anything bought from
HF is CRAP. That goes double for anything with a battery in it.

They succeed because many people, like me,
buy a tool for a job and rarely, if ever use it again.
I have a boatload of HF stuff in that category, but I'd not buy it
for a long-term use where reliability was an issue.

Saving a few bucks on something that doesn't do the job is not being frugal.

Use the HF cells in low-drain devices.
Buy good cells for the camera and a new smart charger. The HF charger
probably won't be friendly to your expensive cells.
Enloops are highly regarded cells, but I guess it also matters what
color the top plastic is. Japanese vs Chinese manufacture.

Ebay cells are a crap shoot. I'm sure some of them are genuine,
but I wouldn't bet money on it. My limited experience with EBAY cellphone
batteries suggests that their specs are exaggerated.

I've had several cameras that ran on AA cells. NONE of them were worth
a crap.
I don't know how they ever sold them new. Must be some degradation in
the sensing circuitry that makes them all useless on NiMH now.

Sometimes, you can find lower capacity cells with lower internal
resistance, but I don't know how to tell without actually measuring it.

 

[D]

Agreed. I needed a reciprocating pneumatic saw and bought two from
Harbor Freight. That's when I discovered that the blade travel was
about 1/8". Useless junk.


There are now 3 or 4 varieties of Eneloop batteries. Five if you
include Chinese fakes. There was a web page showing how to identify
the various varieties, but I can't seem to find it.


I buy quite a few eBay cell phone batteries. My guess(tm) is that
I've bought and used about 200 batteries from random vendors. Many of
them get tested with my West Mtn Radio CBA II for capacity. I have
had some obvious lemons, but they were simply dead, as in no output.
Tested capacity is varies somewhat from LiIon cell to cell. The
switchover from explosive LiPo batteries to safer varieties seems to
have resulted (i.e. not sure) in about a 10% decrease in capacity.
However, the battery label remains the same as with the LiPo including
the rated capacity.


Neither do I. So, I measure it. Some typical results:
<http://www.candlepowerforums.com/vb...-Battery-Performance-An-Intro-to-Ragone-Plots>
<http://www.candlepowerforums.com/vb/showthread.php?278063-AA-Ragone-Plot&highlight=Ragone>
<http://www.candlepowerforums.com/vb/showthread.php?298090-The-AA-NiMH-Performance-Test-Thread>
etc. My results for specific battery follow these tests almost
exactly.

Thanks everyone for the great info on the batteries! I'll have to go
back through all the links, but I appreciate the input!

On Harbor Freight, my experience with them is that if you buy carefully,
you can get what you need at a very good price. I've always had very
broad interests (my downfall, some have suggested... ;-) and I
personally own well over 20 grand worth of tools of all kinds which I
have amassed over the years, from a tiny Swiss watchmaker's lathe to a
full size PowerMatic cabinet saw and 8" jointer (woodworking is my real
passion). I also have a complete set of professional grade automotive
tools (mostly 30+ year old Craftsman & Snap-on). I do know good tools.
I would not buy something requiring a high degree of precision, such
as a jointer, from HF, but I have quite a few pneumatic nailers, impact
tools, and even a compressor of theirs which have all served me quite
well for years. I also have a very nice 3/4 HP drill press of theirs,
as well as one of their tool chest side cabinets. All very servicable.
Is everything they sell the best of its kind? No, of course not. But
for the price (particularly if you combine a sale with one of their
ubiquitous 20% off coupons) I have had no complaints overall, especially
for tools I only use on occasion. And they're very easy with returns, if
you do have a problem. I also have an HF clamp on multimeter which just
yesterday I was using to measure the current drawn by a heater. Out of
curiosity, I checked its readings against an inline measurement using a
Fluke I also own. Dead on.

Dan

 

[Daniel Mandic]

A voracious bugger, he is!

Hi Michael!


But it's knowing its place (rank). I have never seen an abuse posting
to you by Phil...

By the way, where is Eyeore?

 

[Phil Allison]

"Daniel Mandic"

** A voice from the grave.....

Hi Michael!

But it's knowing its place (rank). I have never seen an abuse posting
to you by Phil...

** Responding to a rabid nutter like Terrell serves only to feed his ego.

By the way, where is Eyeore?

** Think Eyesore wanked himself to death.

Or maybe drank himself to the same end.




..... Phil

 

[Daniel Mandic]

"Daniel Mandic"

** A voice from the grave.....

Just a basic-electronics repairing selfmade-man...

** Responding to a rabid nutter like Terrell serves only to feed his
ego.




** Think Eyesore wanked himself to death.

Or maybe drank himself to the same end.

:-(

 

[Daniel Mandic]

Haven't seen anything from you in a long time.

It's always a pleasure to me, Mr. Terrell!

Then check the archives. He's ranted, raved, and cursed at me. I
pointed out he was wrong, with data to back me up on several
occasions. That was when he stopped replying to me. He still claims
there are no 'Chemical Fuses', even though they were used in US
products for decades. (Belfuse)

Phil is IMHO as Sommerwerck said, a capable electronics engineer, but.

He disappeared a few years ago.

Only one Guru left in sci.electronics ;-). (more to come, I hope)