9 LED flashlight batteries question

[Ivan Vegvary]

Have a sh** load of the above. Get them free when shopping at Harbor Freight.
Lately, when batteries fail, I started checking with a voltmeter. Turns out that two of the three batteries always register circa 1.4 volts, while the third is about 0.6± volts. Naturally, I started keeping the two highervoltage cells instead of trashing all three. Is this typical? Have I been needlessly wasting batteries this last 50 years? Never occurred to me tocheck voltages. BTW, these are all AAA cells.

Ivan Vegvary

 

[George Herold]

Have a sh** load of the above.  Get them free when shopping at Harbor Freight.
Lately, when batteries fail, I started checking with a voltmeter.  Turns out that two of the three batteries always register circa 1.4 volts, while the third is about 0.6± volts.  Naturally, I started keeping the two higher voltage cells instead of trashing all three.  Is this typical?  Have I been needlessly wasting batteries this last 50 years?  Never occurred to me to check voltages.  BTW, these are all AAA cells.

Ivan Vegvary

Maybe just cheap batteries. (?)
When you replace with new 'good' batteries do the cells discharge at
the same rate?

George H.

 

[Bill Bowden]

Have a sh** load of the above.  Get them free when shopping at Harbor Freight.
Lately, when batteries fail, I started checking with a voltmeter.  Turns out that two of the three batteries always register circa 1.4 volts, while the third is about 0.6± volts.  Naturally, I started keeping the two higher voltage cells instead of trashing all three.  Is this typical?  Have I been needlessly wasting batteries this last 50 years?  Never occurred to me to check voltages.  BTW, these are all AAA cells.

Ivan Vegvary

I usually check batteries by measuring short circuit current with a
DMM on the 10 amp range. Good alkalines read about 5 amps,
(D,C,AA,AAA) are all about the same. Carbon zincs read about half as
much, or 2 amps. Voltage is misleading, the acid test is short circuit
current.

-Bill

 

[Nobody]

Have a sh** load of the above. Get them free when shopping at Harbor Freight.

Lately, when batteries fail, I started checking with a voltmeter. Turns
out that two of the three batteries always register circa 1.4 volts,
while the third is about 0.6± volts.

Weird.

Normally, an unloaded battery reads close to its nominal voltage
regardless of whether it's brand new or completely flat. The difference is
in the internal resistance, i.e. how quickly the voltage drops as the
current drawn increases.

 

[Phil Allison]

"Ivan Vegvary"

Have a sh** load of the above. Get them free when shopping at Harbor
Freight.
Lately, when batteries fail, I started checking with a voltmeter. Turns out
that two of the three batteries always register circa 1.4 volts, while the
third is about 0.6± volts. Naturally, I started keeping the two higher
voltage cells instead of trashing all three. Is this typical?

** Yes.

Very unlikely for three cells to be identical - one cell is likely to be the
weakest.

The effect seems to be worse when the load current is high - as in your
example.

Saw this over and over with groups of 4 x alkaline AAs used in RC receivers.

Why I changed to using NiCds.


..... Phil

 

[Phil Allison]

"Nobody"

" Lately, when batteries fail, I started checking with a voltmeter. Turns
out that two of the three batteries always register circa 1.4 volts,
while the third is about 0.6± volts."

Weird.

** Not all all.

3.4 volts is where the LED torch begins to fade out - under load it will be
much less.

Normally, an unloaded battery reads close to its nominal voltage
regardless of whether it's brand new or completely flat.

** Absolute GARBAGE !!!

The difference is in the internal resistance,

** That is a separate fact.

Cell voltage does relate to remaining capacity fairly well and very well if
the cell is under its normal load.

Not true for rechargeable types though.



.... Phil

 

[Jamie]

Weird.

Normally, an unloaded battery reads close to its nominal voltage
regardless of whether it's brand new or completely flat. The difference is
in the internal resistance, i.e. how quickly the voltage drops as the
current drawn increases.

Really? sounds a little bogus to me.. Since i've seen a good many
cells exhibit low voltage after drain.

If you are referring to rechargeable's, that could be a different story.

Jamie

 

[Michael Black]

They probably wouldn't be giving them away free if the batteries in them were
any good.

I don't know. IN the old days "batteries not icluded" wsa pretty normal,
but most things I've bought in recent years did have batteries when
applicable. And I find the batteries generally fairly good. Not
noticeably bad.

I don't know where the pricing comes from. I keep buying LED flashlights
(torches in some countries), and they come with batteries. And then it
often seems to make sense to buy a new one when the batteries do die out
An exaggeration, but I keep buying the LED flashlights because they keep
adding LEDs to them, making them brighter.

FOr that matter, I've needed button cells to replace worn out button cells
in various things, and for those that need the size, it's cheaper to buy a
99cent or $1.49 laser pointer for the batteries than buy the button cells
separately. Yes, you can get the cells cheap in some circles, but
generally not as handy as where the laser pointers get sold.

Ironically, the one LED flashlight that I care most about is faulty. I
have a 2AA Maglite, and a few years back got an LED replacement bulb,
which worked fine, but now has gotten flakey. I'm not sure if it's the
contacts, the LED module, or the Maglite. Ironic since the Maglite wasn't
cheap, and neither was the LED replacement, but the cheap LED flashlights
generally are fine.

Michael

 

[Michael Black]

I hate flashlights that use button cells. While LR44 or 2CR2025 cells
are relatively inexpensive, they really don't have a lot of capacity.
I have a 2AA maglite and a Fizer I-Beam X1 which takes 1 AA. I used
to have a Gerber "Infinity Ultra Task Light" 22-80010, but someone
stole it; 60+ hours on one AA. Button-cell flashlights are for day-
outings.

Actually my need for button cells is for that kitchen timer I have lying
her waiting for a battery. I've bought laser pointers for the button
cells for those kitchen timers before, I think I got an analog battery
operated clock going with a button cell from a laser pointer too.

I also have a battery powered pocket watch that needs a new battery. WHen
I finally got the back cover off, I discovered it used "button cells" like
you find in computers, CR2026 or whatever, for the built in LED
flashlight, which still works fine (it used a red LED, so I never used it
that much). But the clock runs off a separate battery, and that one is
smaller, I think smaller than the laser pointer batteries. SO that too
sits opened, waiting for me to get around to looking for a suitable
battery.

Michael

 

[Bob Masta]

Actually my need for button cells is for that kitchen timer I have lying
her waiting for a battery. I've bought laser pointers for the button
cells for those kitchen timers before, I think I got an analog battery
operated clock going with a button cell from a laser pointer too.

For certain items like kitchen timers, clocks, and
calculators I often use a trick: Old 9V batteries from
smoke detectors, etc, still have a lot of juice left when
they are no longer useful in their original application (at
least compared to the low-voltage trickle needed by LCD
display devices). I build a tiny voltage regulator using a
couple of NPNs and LEDs (forward biased through a high R to
serve as a sharp-cutoff Vref). The whole works can be
soldered together on top of a 9V battery clip, though I've
also made tiny PCBs from scraps.

The result is that the 9V battery typically powers the
device for a year or 2, at least, before it can't maintain
the 3V needed for the device. By then I've usually
collected plenty more 9V batteries. Snap the old one out
and the new one in!

Of course, the Frankenstein timer/clock/whatever with a
hulking 9V battery strapped to it is not likely to appeal to
anyone with delicate sensitivities or fine aesthetic sense
(or maybe *any* aesthetic sense!), but I get a kick out of
the whole idea of running it "for free".

Best regards,


Bob Masta

DAQARTA v7.21
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
Frequency Counter, Pitch Track, Pitch-to-MIDI
FREE Signal Generator, DaqMusic generator
Science with your sound card!

 

[Michael Black]

For certain items like kitchen timers, clocks, and
calculators I often use a trick: Old 9V batteries from
smoke detectors, etc, still have a lot of juice left when
they are no longer useful in their original application (at
least compared to the low-voltage trickle needed by LCD
display devices). I build a tiny voltage regulator using a
couple of NPNs and LEDs (forward biased through a high R to
serve as a sharp-cutoff Vref). The whole works can be
soldered together on top of a 9V battery clip, though I've
also made tiny PCBs from scraps.

I once bought a nice LCD clock for a couple of dollars, it was nice
because the readout was larger than what I'd found at that price level.
And when the button cell wore out, I didn't even bother looking for a
button cell, I just soldered in an AA battery, hanging it off the back.
The AA battery does last forever, I can't remember when I soldered in the
first one, but it was at least a decade ago, and I've replaced it once,
and it keeps on ticking.

I guess I wanted the kitchen timer to be more portable.

And yes, I do change the smoke detectors after a year or so, and thus the
"old" batteries get used for something else, that isn't as important, so
the smoke detectors run fine but the batteries aren't wasted.

Michael

 

[Jamie]

Naaaah! Button cells are for my pocket Nano Light, for occasional
use, to peer into a mailbox after dark, etc.

...Jim Thompson

Ah, so that's you I see out at night rooming the streets?

Jamie

 

[Jamie]

Just lately we've had numerous discount stores spring up all over the
place like Poundland where everything is 1 GBP, usually there's quite a
few places you can buy a card of button or coin cells for around £1.
IIRC the button cells are about 30 in assorted sizes per card, the coin
cells are only 8 - 4x 2032, 2x 2025 & 2x 2016.

The coin cells mostly go in the outside temperature sender for my desk
clock-thermometer, they don't last quite as long as the expensive named
brand ones, but at that price, who cares.

We have junk stores around here too. I have a package of 9 i think it
was of CR2032's for under 2 bucks. And they also have a variety pack of
coin cells for that price, too.

The CR2032's work great for my key fob that seems to like eating cells
for my Jeep. It has a keyless entry and ignition system.

Jamie