spamme9 wrote:
> BillW50 wrote:
>> Val wrote:
>>> Doesn't wear mean a lessened ability to take/hold a charge?
>>
>> Well not really. It means that the capacity (run time - kind of like
>> your gas tank gets smaller and smaller) is dropping. A Li-Ion battery
>> will continue to take and hold a charge till about 95% of the capacity
>> is gone. Then it starts having a problem taking and holding a charge.
>>
> My experience is all with laptops prior to 2005, but I've never had
> a battery fail because it wouldn't hold a charge. Mine fail because
> the internal resistance goes up to the point that the laptop
> shuts down WELL before consuming all the available electrons.
> I've done extensive capacity tests at various currents.
> The electrons are in there, the laptop just won't take 'em.
>
> While on the subject...
> I have two laptop batteries where ALL 8 of the cells are open-circuit
> with no signs of overheating. I can understand how one cell of a series
> string can pop it's internal breaker, but all 8???
> Came with a used laptop, so no idea the history.

Well high power drain this is common fault of Li-Ion batteries. Although
low power drain devices the voltage drops below 2.8v or so and the
safety circuits kicks in and prevents the battery from taking any charge
for safety reasons.

And for one cell circuit breaking its connection, its in series with the
other cells. So how are you reading it? Did you disassemble the pack? As
I am not sure if safety circuits all work the same design wise or not.
But the idea is the same.

1) Excessive drain (short) they open permanently or temporary.

2) Too hot, they open permanently or temporary. And they have a seal
that can blow too if the pressure gets too high.

3) Voltage drops too low, they open permanently. Charging when too low
can cause the battery to explode.

--
Bill
Asus EEE PC 8GB 1GB SoDIMM Adata 16GB
Windows XP SP2 and Xandros Linux

"BillW50" <BillW50@aol.kom> wrote in message
news:gfvsl7$snt$1@nntp.motzarella.org...
> Barry Watzman wrote:
>> I also don't agree with Bill. But, that said, there is a lot of unit to
>> unit (really model to model) variation. What can kill a battery is a
>> combination of overcharging and heat (either from within the battery or
>> from external sources). Some laptops are well designed in these regards,
>> others, however are not (I'd say that most are not, based on experience).
>
> What Li-Ion battery chargers over charge the battery? As over charging
> Li-Ion batteries could cause the battery to explode. This is a big no-no!
> So I seriously doubt any laptop is over charging batteries.
>

The problem here is that a lot of advice about removal of the battery blames
overcharging, and to the less technically minded users, this seems a
perfectly reasonable explanation. Thus it gets propagated (and has even
turned up here).

> And that 20% per year was quoted at room temperature and keeping the
> battery voltage charged to 4.2v per cell. And that is what I have found
> too. Change either or, and my results would be different too.
>

The actual depletion rate depends very much on the battery construction, but
generally 20% loss of charge per year at 20 C is a good figure for most
constructions. There is a relatively new construction from Sony that has a
lower average voltage (of 3.4 volts per cell) and a charge loss rate of
nearly 20% *per month*.

>> The best advice for a laptop to be used in a predominantly non-mobile,
>> almost always on AC application is to remove the battery (if you need a
>> UPS, get a UPS. A $30 ups is cheaper than a $200 lithium battery).
>
> I too feel the same way. Although I seem to recall M.I.5¾ believing that
> Li-Ion lasts longer if they get some occasional use (I personally can't
> say either way on that one).

This is advice from the battery manufacturers. My own experience suggests
that it may be the case.

> But I feel this is true of lead acid batteries, but M.I.5¾ disagrees with
> me there.
>

This disagreement comes from the fact that the act of discharging a lead
acid battery actually does a small amount of physical damage. This is
because both the positive and negative plates get larger as they absorb the
sulphate from the acid electrolyte. This size change causes the plate to
shed a small amount of the brittle active material. Simply keeping the
battery charged keeps the plates a constant size. If the battery is allowed
to stand, the self discharge causes the plates once more to absorb sulphate
from the electrolyte. If the lead sulphate is not converted back to lead
(-ve) and lead dioxide (+ve) via a regular charge it looses its spongy form
and becomes a hard deposit. Once it becomes hard, it ceases to absorb the
electrolyte and becomes impossible to break down by charging. The shed
material and the sulphation (as it is called) are the 2 failure modes for
lead acid batteries.

The ideal storage mode for lead acid batteries is to constantly pass a small
charging current through them that just balances the charge loss due to self
discharge. In practice, it is more usual to give them a periodic charge to
offset the self discharge every 2 to 4 weeks.

spamme9 wrote:
> BillW50 wrote:
>> Val wrote:
>>> Doesn't wear mean a lessened ability to take/hold a charge?
>>
>> Well not really. It means that the capacity (run time - kind of like
>> your gas tank gets smaller and smaller) is dropping. A Li-Ion battery
>> will continue to take and hold a charge till about 95% of the capacity
>> is gone. Then it starts having a problem taking and holding a charge.
>>
> My experience is all with laptops prior to 2005, but I've never had
> a battery fail because it wouldn't hold a charge. Mine fail because
> the internal resistance goes up to the point that the laptop
> shuts down WELL before consuming all the available electrons.
> I've done extensive capacity tests at various currents.
> The electrons are in there, the laptop just won't take 'em.
>
> While on the subject...
> I have two laptop batteries where ALL 8 of the cells are open-circuit
> with no signs of overheating. I can understand how one cell of a series
> string can pop it's internal breaker, but all 8???
> Came with a used laptop, so no idea the history.

Well high power drain this is common fault of Li-Ion batteries. Although
low power drain devices the voltage drops below 2.8v or so and the
safety circuits kicks in and prevents the battery from taking any charge
for safety reasons.

And for one cell circuit breaking its connection, its in series with the
other cells. So how are you reading it? Did you disassemble the pack? As
I am not sure if safety circuits all work the same design wise or not.
But the idea is the same.

1) Excessive drain (short) they open permanently or temporary.

2) Too hot, they open permanently or temporary. And they have a seal
that can blow too if the pressure gets too high.

3) Voltage drops too low, they open permanently. Charging when too low
can cause the battery to explode.

--
Bill
Asus EEE PC 8GB 1GB SoDIMM Adata 16GB
Windows XP SP2 and Xandros Linux

M.I.5¾ wrote:
> "AJL" <nomail@fakeaddress.com> wrote in message
> news:scu6i4d4o7pkc10l84ujm8ajts6ejk7am3@4ax.com...
>> Barry Watzman <WatzmanNOSPAM@neo.rr.com> wrote:
>>
>>> What can kill a battery is a
>>> combination of overcharging and heat (either from within the battery or
>> >from external sources). Some laptops are well designed in these
>>> regards, others, however are not.
>>> (I'd say that most are not, based on experience).
>> Rather a poor supposition don't you think? The number of laptops that
>> are poorly designed in your "experience" must be minuscule compared to
>> the thousands of other models in service.
>>
> Actually, I rather agree with the poster you replied to. Poorly designed in
> this case means placing heat generating components such as the hard disc
> drive or processor near to the battery such that it warms up in use. From
> what I can tell, little consideration is given to the temperature problems
> of the battery and if a laptop design is encountered that doesn't
> significantly heat the battery, then it is more by luck than any design
> requirement. The laptop makers have no real vested interest in protecting
> the battery from the effects of heat - not at a $100-200 a go.
>
>
You are most probably right for most laptops. However, I believe that
business series pay more attention to such matters since they need to
convince big accounts managers of the quality / reliability of their
products.

Whichever way we look at the battery issue, I find it unconscionable
that battery replacement would be so expensive compared to the price of
laptop. Is it the same issue as printer cartridges or is there a really
valid reason for those sky high prices?

--
John Doue

"AJL" <nomail@fakeaddress.com> wrote in message
news:scu6i4d4o7pkc10l84ujm8ajts6ejk7am3@4ax.com...
> Barry Watzman <WatzmanNOSPAM@neo.rr.com> wrote:
>
>>What can kill a battery is a
>>combination of overcharging and heat (either from within the battery or
>>from external sources). Some laptops are well designed in these
>>regards, others, however are not.
>
>>(I'd say that most are not, based on experience).
>
> Rather a poor supposition don't you think? The number of laptops that
> are poorly designed in your "experience" must be minuscule compared to
> the thousands of other models in service.
>
Actually, I rather agree with the poster you replied to. Poorly designed in
this case means placing heat generating components such as the hard disc
drive or processor near to the battery such that it warms up in use. From
what I can tell, little consideration is given to the temperature problems
of the battery and if a laptop design is encountered that doesn't
significantly heat the battery, then it is more by luck than any design
requirement. The laptop makers have no real vested interest in protecting
the battery from the effects of heat - not at a $100-200 a go.

M.I.5¾ wrote:
> "AJL" <nomail@fakeaddress.com> wrote in message
> news:scu6i4d4o7pkc10l84ujm8ajts6ejk7am3@4ax.com...
>> Barry Watzman <WatzmanNOSPAM@neo.rr.com> wrote:
>>
>>> What can kill a battery is a
>>> combination of overcharging and heat (either from within the battery or
>> >from external sources). Some laptops are well designed in these
>>> regards, others, however are not.
>>> (I'd say that most are not, based on experience).
>> Rather a poor supposition don't you think? The number of laptops that
>> are poorly designed in your "experience" must be minuscule compared to
>> the thousands of other models in service.
>>
> Actually, I rather agree with the poster you replied to. Poorly designed in
> this case means placing heat generating components such as the hard disc
> drive or processor near to the battery such that it warms up in use. From
> what I can tell, little consideration is given to the temperature problems
> of the battery and if a laptop design is encountered that doesn't
> significantly heat the battery, then it is more by luck than any design
> requirement. The laptop makers have no real vested interest in protecting
> the battery from the effects of heat - not at a $100-200 a go.
>
>
You are most probably right for most laptops. However, I believe that
business series pay more attention to such matters since they need to
convince big accounts managers of the quality / reliability of their
products.

Whichever way we look at the battery issue, I find it unconscionable
that battery replacement would be so expensive compared to the price of
laptop. Is it the same issue as printer cartridges or is there a really
valid reason for those sky high prices?

--
John Doue

Doesn't wear mean a lessened ability to take/hold a charge? If the battery,
at present full charge, runs less time than it did when new, isn't that
runtime difference the amount of wear?

As to "citation needed", I interpret that to indicate a lack of validation
of what's posted on the wiki. Doesn't mean it's not true, just not yet
supported by evidence. Thus, not be trusted (or rather, to trusted less than
one might trust other wiki entries.)

Whereas my Gateway laptop, which gets a lot of use on battery, still has a
high percentage of its new capacity, my iPod sucks. It drains away so fast
just sitting unusedI can see the electrons piling up on the floor.

"M.I.5¾" <no.one@no.where.NO_SPAM.co.uk> wrote in message
news:492525a4_1@glkas0286.greenlnk.net...

"Val" <vmanes@NOSPAMrap.midco.net> wrote in message
news:yO-dnYowtqhe1L_UnZ2dnUVZ_qzinZ2d@midco.net...
> Tell that to my three year old battery, kept in the laptop, used almost
> daily, put back on AC so it stays topped off, stored at room temperature.
> Battery wear, as indicated by mobilemeter program, and verified by actual
> run time, is only 15%.
>
> I see an awful lot of "citation needed" in that wiki.
>

Wear and charge are different things.

The "citation needed" is there for a good reason.