Re: batteries (was Waiting for Verizon..) [telecom]



<hancock4@xxxxxxxxxxxx> wrote:
On Apr 7, 12:49 pm, klu...@xxxxxxxxx (Scott Dorsey) wrote:

No, they are not as rugged as any battery gets.  They won't last more
than two or three deep discharges; the plates will warp and the cells will
short out and then you pitch them.

A question about 'deep discharges' for a car battery. If someone
leaves their headlights on and the 'battery runs down', is that a
"deep discharge" situation? That is, if someone does that, have they
ruined their car battery and need a replacement?

Do that two or three times and your battery won't hold a charge at all. Doing
this dramatically shortens the life of your battery.

One time my alternator died. My mechanic said I'd be ok driving from
home to his garage for a fix. While there he had to add water to the
battery (this was some years ago). Did a situation like that
constitute a "deep discharge"?

Possibly. May have been fine, may not have, depending on how far the battery
voltage dropped. Used to be cars had a voltmeter on the instrument panel so
you could see that you were down below 12V and possibly doing some harm to the
battery.

Side note 2: I wish I could remember where I read the technical
description of dry cells intended for magneto local-battery telephone
service or "intermitent use". I recall seeing such No. 6 cells in
magneto phones so marked. Such cells had a chemistry intended for
such service and was able to replenish itself a bit after a brief use,
extending their lifespan. Said description also explained how they
made "heavy duty" dry cells.
Apparently there were various types of carbon-zinc chemistries for
industrial service dry cell batteries that ordinary consumers wouldn't
see.

Primary cells and rechargeable accumulator cells are very different things.
I think what you're talking about are "heavy duty" batteries which use a
manganese-dioxide electrolyte and then a zinc chloride layer around the
zinc casing instead of the ammonium chloride that "regular" batteries used.
This reduces self-discharge so the batteries don't go bad as quickly in
intermittent service, and it also increases the current for brief time spans.

Actually, I haven't seen the old style batteries sold in a long
time; everything in common consumer stores is alkaline or a newer
type. However, the old style type are often included with TV remote
units or packaged with cheap flashlights.

That would be a "heavy duty" battery, which has been pretty much entirely
replaced by alkaline batteries today.

Side note 3: With cell phone batteries, do the batteries sold today
have the "memory" problem, that is, is it necessary or _prudent_ to
discharge them fully before recharging them? It seems most people
recharge their cell phones at their convenience, not waiting until
the phone is completely drained, and they get a great many charging
cycles out of their. (On my current cellphone, a plain vanilla LG, I
get four hours of talk time per charge, which I guess is good.)

No battery has had memory for the past thirty years or so. You're much
more apt to damage any sort of battery stack by fully discharging it than
not.

Cell phone batteries today usually have computer control inside with a
little processor that equalizes the load between the individual cells
both on charging and discharging, to make the cells last a lot longer,
so none of these issues are a problem.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

.



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