Yesterday, I dropped my "Hard-Case" LED torch on the wooden deck outside
my house. It went out, and wouldn't turn on again. This surprised me,
because the torch is rebustly made, and LEDs aren't that fragile.

On a hunch, I replaced the batteries. It works fine.

Further experiment showed that one of the previous batteries, and
Energise Alkaline, had died. It's capable of delivering only a few
microamps, and has an EMF of about 0.5V.

I've never heard of a dry cell failing like that.

Sylvia.

Further experiment showed that one of the previous batteries,
an Energizer alkaline, had died. It's capable of delivering only
a few microamps, and has an EMF of about 0.5V.
I've never heard of a dry cell failing like that.

Alkaline cells are encased in a sleeve that reverses their polarity -- the
center electrode would otherwise be negative. It's possible that the sleeve
was damaged or knocked loose.

William Sommerwerck wrote:
Further experiment showed that one of the previous batteries,
an Energizer alkaline, had died. It's capable of delivering only
a few microamps, and has an EMF of about 0.5V.
I've never heard of a dry cell failing like that.

Alkaline cells are encased in a sleeve that reverses their polarity -- the
center electrode would otherwise be negative. It's possible that the sleeve
was damaged or knocked loose.



Well, I suppose some may be constructed that way. Close examination of
the failed one shows that the positive button is just an extension of
the external casing, and the negative is a separate area insulated from
it. That is, much like a zink-carbon battery in reverse.

Sylvia.

In message , Sylvia Else
writes
Well, I suppose some may be constructed that way. Close examination of
the failed one shows that the positive button is just an extension of
the external casing, and the negative is a separate area insulated from
it. That is, much like a zink-carbon battery in reverse.
Last time I ripped an alkaline cell apart (a *long* time ago) the
negative terminal was attached to a long thin spike pushed down the
centre of the cell, it's possible I suppose that an impact may have
broken this close to the terminal or it may have pierced an insulator or
seal inside the cell.

BTW, I'd not describe an alkaline cell as 'dry', to my mind that
suggests a zinc carbon cell.

Sylvia.

--
Clint Sharp

Sylvia Else wrote:
Yesterday, I dropped my "Hard-Case" LED torch on the wooden deck outside
my house. It went out, and wouldn't turn on again. This surprised me,
because the torch is rebustly made, and LEDs aren't that fragile.

On a hunch, I replaced the batteries. It works fine.

Further experiment showed that one of the previous batteries, and
Energise Alkaline, had died. It's capable of delivering only a few
microamps, and has an EMF of about 0.5V.

I've never heard of a dry cell failing like that.

Sylvia.

That`s one of the reasons professionals almost always use Duracells in
radio microphone packs. It`s not uncommon to find an energiser battery
which gives no voltage unless you press on the end terminals. In the
Duracell 9volt 'PP3' the connecting strips between cells are spot
welded, in many other makes they rely on contact pressure alone to make
a good connection with inconsistant results, especialy under heavy load.

Only yesterday I pulled apart a Panasonic PP3 which had failed
prematurely, to find that the positive contact made it`s only connection
to the stack by having sharp 'points' which are intended to pierce the
soft plastic covering of the cells. Pressing down on the battery
connector would make the voltage come and go.

Duracell PP3's are a handy source of sub AAA cells btw.

Ron

I'd not describe an alkaline cell as "dry". To my mind,
that suggests a carbon-zinc cell.

It's dry in the sense that the electrolyte doesn't slosh around (as it does
in a lead-acid storage battery).

That`s one of the reasons professionals almost always use Duracells
in radio microphone packs. It`s not uncommon to find an Energizer
battery which gives no voltage unless you press on the end terminals.
In the Duracell 9V PP3, the connecting strips between cells are spot
welded, in many other makes they rely on contact pressure alone to
a good connection with inconsistant results, especialy under heavy load.

I've never had any cell, from any manufacturer, fail in that way (that I was
aware of).

On the other hand, I've had Duracells leak and damage the equipment they
were in. In one case I was able to clean up the mess. In the other case,
Mallory * was obliged to replace part of the device (an Olympus dictating
machine).

I've never had an Eveready * or Toshiba leak. I don't use Duracells.

I just realized the OP was talking about batteries, not cells.
Nevertheless...

* I'm so old that I remember when Mallory sold alkaline batteries through
parts distributors. In the early 60s, they were still a bit novel. Nor can I
forget Eveready's classic "9 Lives" logo.

William Sommerwerck wrote:

I just realized the OP was talking about batteries, not cells.

I used the word loosely. They were in fact cells.

Sylvia.