Greetings,

I have a battery problem here. The problem is that the laptop can only
be turned ON when there is an AC source which means it can only work
when I plugged in the charger. If I turned OFF the charger, the
laptop suddenly turned OFF as if I am not using any battery. In
Windows, the battery details is not shown as if there is no battery
inside. Is it because of the battery or the motherboard? Because I
bumped a few forums saying that it might have been caused by faulty
daughterboard. Can anyone help me fix this problem? Its really
troublesome having a mobile computer which is not so mobile. Thank
you.

DuraBook R15D
Battery chemistry - Lithium Ion.

"gha4" <no@spam.invalid> wrote in message
news:12l7ebsh89hdh0f@news.supernews.com
> Greetings,
>
> I have a battery problem here. The problem is that the laptop can only
> be turned ON when there is an AC source which means it can only work
> when I plugged in the charger. If I turned OFF the charger, the
> laptop suddenly turned OFF as if I am not using any battery. In
> Windows, the battery details is not shown as if there is no battery
> inside. Is it because of the battery or the motherboard? Because I
> bumped a few forums saying that it might have been caused by faulty
> daughterboard. Can anyone help me fix this problem? Its really
> troublesome having a mobile computer which is not so mobile. Thank
> you.
>
> DuraBook R15D
> Battery chemistry - Lithium Ion.

When most Li-Ion batteries falls somewhere around 3.2 volts per cell, a
protection circuit kicks in and opens up the circuit. Or the protection
is in the laptop itself, in either case it looks like there is not
battery in the laptop.

This is good for two reasons. One Li-Ion batteries can explode if you
try to recharge very low cells. And second, if it didn't explode, the
laptop would get very hot (especially if you are using the laptop as
well) when trying to put a charge in the battery which isn't taking it
too well. Yes it could be something else other than a battery. But all
Li-Ion batteries will do this sooner or later.

If you use your battery a lot, like everyday. Li-Ion batteries usually
don't last more than 6 months. If you don't use them but leave them in
the laptop on AC, they will over last about 2 years. Why? Because laptop
manufactures over charge them (up to 4.2 volts per cell) so they can get
the maximum amount of battery power out of them. This is good for sales,
but bad for battery lifetime.

Best thing to do is to remove them before they reach 100% charge. I know
sometimes you can't, but don't leave them in the laptop when they are
not charging or being used. With care, they can last over 10 years if
you don't use them too much. Remember they are only good for between 300
to 500 recharges too.

--
Bill

"BillW50" <BillW50@aol.kom> wrote in message
news:4554d038$0$1347$834e42db@reader.greatnowhere. com...
> "gha4" <no@spam.invalid> wrote in message
> news:12l7ebsh89hdh0f@news.supernews.com
>> Greetings,
>>
>> I have a battery problem here. The problem is that the laptop can only
>> be turned ON when there is an AC source which means it can only work
>> when I plugged in the charger. If I turned OFF the charger, the
>> laptop suddenly turned OFF as if I am not using any battery. In
>> Windows, the battery details is not shown as if there is no battery
>> inside. Is it because of the battery or the motherboard? Because I
>> bumped a few forums saying that it might have been caused by faulty
>> daughterboard. Can anyone help me fix this problem? Its really
>> troublesome having a mobile computer which is not so mobile. Thank
>> you.
>>
>> DuraBook R15D
>> Battery chemistry - Lithium Ion.
>
> When most Li-Ion batteries falls somewhere around 3.2 volts per cell, a
> protection circuit kicks in and opens up the circuit. Or the protection is
> in the laptop itself, in either case it looks like there is not battery in
> the laptop.
>
> This is good for two reasons. One Li-Ion batteries can explode if you try
> to recharge very low cells. And second, if it didn't explode, the laptop
> would get very hot (especially if you are using the laptop as well) when
> trying to put a charge in the battery which isn't taking it too well. Yes
> it could be something else other than a battery. But all Li-Ion batteries
> will do this sooner or later.
>
> If you use your battery a lot, like everyday. Li-Ion batteries usually
> don't last more than 6 months. If you don't use them but leave them in the
> laptop on AC, they will over last about 2 years. Why? Because laptop
> manufactures over charge them (up to 4.2 volts per cell) so they can get
> the maximum amount of battery power out of them. This is good for sales,
> but bad for battery lifetime.
>

4.2 volts is not overcharging the cell. This is in fact the correct
terminal voltage for any Li-ion chemistry cell. If they were being
overcharged, the fact would manifest itself when the battery errupted in a
large fireball. It has been claimed (and it is Sony (of exploding battery
fame) doing the claiming), that some manufacturers are charging their
batteries at a higher current than they should be for at least part of the
cycle. It is, of course, entirely possible that Sony are attempting to
limit their liability in the matter, especially as abuse of the battery is
an extremely dangerous thing to do.

> Best thing to do is to remove them before they reach 100% charge. I know
> sometimes you can't, but don't leave them in the laptop when they are not
> charging or being used. With care, they can last over 10 years if you
> don't use them too much. Remember they are only good for between 300 to
> 500 recharges too.
>

The principal cause of premature battery failure is due to the battery being
heated by other heat producing parts in the laptop. Even relatively modest
amounts of heat can destroy a battery prematurely. Overcharging is not the
cause. The best way to get the best life is to remove the battery while
running on AC (and the battery isn't being charged). It is because the
damage was done while the battery was inserted, that the myth started about
batteries being overcharged.

"M.I.5?" <no.one@no.where.NO_SPAM.co.uk> wrote in message
news:45582bb4$1_1@glkas0286.greenlnk.net
> "BillW50" <BillW50@aol.kom> wrote in message
> news:4554d038$0$1347$834e42db@reader.greatnowhere. com...
>> "gha4" <no@spam.invalid> wrote in message
>> news:12l7ebsh89hdh0f@news.supernews.com
>>> Greetings,
>>>
>>> I have a battery problem here. The problem is that the laptop can
>>> only be turned ON when there is an AC source which means it can
>>> only work when I plugged in the charger. If I turned OFF the
>>> charger, the laptop suddenly turned OFF as if I am not using any
>>> battery. In Windows, the battery details is not shown as if there
>>> is no battery inside. Is it because of the battery or the
>>> motherboard? Because I bumped a few forums saying that it might
>>> have been caused by faulty daughterboard. Can anyone help me fix
>>> this problem? Its really troublesome having a mobile computer which
>>> is not so mobile. Thank you.
>>>
>>> DuraBook R15D
>>> Battery chemistry - Lithium Ion.
>>
>> When most Li-Ion batteries falls somewhere around 3.2 volts per
>> cell, a protection circuit kicks in and opens up the circuit. Or the
>> protection is in the laptop itself, in either case it looks like
>> there is not battery in the laptop.
>>
>> This is good for two reasons. One Li-Ion batteries can explode if
>> you try to recharge very low cells. And second, if it didn't
>> explode, the laptop would get very hot (especially if you are using
>> the laptop as well) when trying to put a charge in the battery which
>> isn't taking it too well. Yes it could be something else other than
>> a battery. But all Li-Ion batteries will do this sooner or later.
>>
>> If you use your battery a lot, like everyday. Li-Ion batteries
>> usually don't last more than 6 months. If you don't use them but
>> leave them in the laptop on AC, they will over last about 2 years.
>> Why? Because laptop manufactures over charge them (up to 4.2 volts
>> per cell) so they can get the maximum amount of battery power out of
>> them. This is good for sales, but bad for battery lifetime.
>>
>
> 4.2 volts is not overcharging the cell. This is in fact the correct
> terminal voltage for any Li-ion chemistry cell. If they were being
> overcharged, the fact would manifest itself when the battery errupted
> in a large fireball. It has been claimed (and it is Sony (of
> exploding battery fame) doing the claiming), that some manufacturers
> are charging their batteries at a higher current than they should be
> for at least part of the cycle. It is, of course, entirely possible
> that Sony are attempting to limit their liability in the matter,
> especially as abuse of the battery is an extremely dangerous thing to
> do.
>
>> Best thing to do is to remove them before they reach 100% charge. I
>> know sometimes you can't, but don't leave them in the laptop when
>> they are not charging or being used. With care, they can last over
>> 10 years if you don't use them too much. Remember they are only good
>> for between 300 to 500 recharges too.
>>
>
> The principal cause of premature battery failure is due to the
> battery being heated by other heat producing parts in the laptop. Even
> relatively modest amounts of heat can destroy a battery
> prematurely. Overcharging is not the cause. The best way to get the
> best life is to remove the battery while running on AC (and the
> battery isn't being charged). It is because the damage was done
> while the battery was inserted, that the myth started about batteries
> being overcharged.

Nope, I strongly disagree. Holding a Li-Ion battery at 4.2 volts per
cell will kill them in about 2 years (even if you have never drained
them). Holding them at 4.1 volts per cell, they will last 3 to 4 years
or
more. You call overcharging when they explode, while I call overcharging
when damage is being done.

Li-Ion batteries likes being left alone. And they do best just sitting
at between 40% to 50% of capacity doing absolutely nothing. Lazy beings
they are. And they can enjoy life 10 years or more in this state.

I am sure heat isn't good them them in a hot laptop. But I have seen
Li-Ion batteries left in laptops that were only used briefly about twice
per year (for a few hours) and the rest of the time the laptops were
off, While the AC kept the cells at 4.2 volts and it still killed the
Li-Ion batteries. No heat was responsible here. It had to be the 4.2
volts that slowly killed them. There is no other reason that I can think
of.

There is also a discussion in:

sci.chem.electrochem.battery

That discusses this in detail.

Oh and they want references of your claim that under voltage cells can
explode. They have never heard of this. They stated that a small amount
of current is always safe and fine to try to bring one back to life.

And they also tell me that Li-Ion batteries once drops down to a low
level between the plates (the voltage potential), they naturally open.
And trying to recharge them won't change anything. But you and I believe
there is a safety circuit that causes them to open within the pack. So
who is right?

--
Bill

"BillW50" <BillW50@aol.kom> wrote in message
news:45588793$0$1350$834e42db@reader.greatnowhere. com...
> "M.I.5?" <no.one@no.where.NO_SPAM.co.uk> wrote in message
> news:45582bb4$1_1@glkas0286.greenlnk.net
>> "BillW50" <BillW50@aol.kom> wrote in message
>> news:4554d038$0$1347$834e42db@reader.greatnowhere. com...
>>> "gha4" <no@spam.invalid> wrote in message
>>> news:12l7ebsh89hdh0f@news.supernews.com
>>>> Greetings,
>>>>
>>>> I have a battery problem here. The problem is that the laptop can
>>>> only be turned ON when there is an AC source which means it can
>>>> only work when I plugged in the charger. If I turned OFF the
>>>> charger, the laptop suddenly turned OFF as if I am not using any
>>>> battery. In Windows, the battery details is not shown as if there
>>>> is no battery inside. Is it because of the battery or the
>>>> motherboard? Because I bumped a few forums saying that it might
>>>> have been caused by faulty daughterboard. Can anyone help me fix
>>>> this problem? Its really troublesome having a mobile computer which
>>>> is not so mobile. Thank you.
>>>>
>>>> DuraBook R15D
>>>> Battery chemistry - Lithium Ion.
>>>
>>> When most Li-Ion batteries falls somewhere around 3.2 volts per
>>> cell, a protection circuit kicks in and opens up the circuit. Or the
>>> protection is in the laptop itself, in either case it looks like
>>> there is not battery in the laptop.
>>>
>>> This is good for two reasons. One Li-Ion batteries can explode if
>>> you try to recharge very low cells. And second, if it didn't
>>> explode, the laptop would get very hot (especially if you are using
>>> the laptop as well) when trying to put a charge in the battery which
>>> isn't taking it too well. Yes it could be something else other than
>>> a battery. But all Li-Ion batteries will do this sooner or later.
>>>
>>> If you use your battery a lot, like everyday. Li-Ion batteries
>>> usually don't last more than 6 months. If you don't use them but
>>> leave them in the laptop on AC, they will over last about 2 years.
>>> Why? Because laptop manufactures over charge them (up to 4.2 volts
>>> per cell) so they can get the maximum amount of battery power out of
>>> them. This is good for sales, but bad for battery lifetime.
>>>
>>
>> 4.2 volts is not overcharging the cell. This is in fact the correct
>> terminal voltage for any Li-ion chemistry cell. If they were being
>> overcharged, the fact would manifest itself when the battery errupted
>> in a large fireball. It has been claimed (and it is Sony (of
>> exploding battery fame) doing the claiming), that some manufacturers
>> are charging their batteries at a higher current than they should be
>> for at least part of the cycle. It is, of course, entirely possible
>> that Sony are attempting to limit their liability in the matter,
>> especially as abuse of the battery is an extremely dangerous thing to
>> do.
>>
>>> Best thing to do is to remove them before they reach 100% charge. I
>>> know sometimes you can't, but don't leave them in the laptop when
>>> they are not charging or being used. With care, they can last over
>>> 10 years if you don't use them too much. Remember they are only good
>>> for between 300 to 500 recharges too.
>>>
>>
>> The principal cause of premature battery failure is due to the
>> battery being heated by other heat producing parts in the laptop. Even
>> relatively modest amounts of heat can destroy a battery
>> prematurely. Overcharging is not the cause. The best way to get the
>> best life is to remove the battery while running on AC (and the
>> battery isn't being charged). It is because the damage was done
>> while the battery was inserted, that the myth started about batteries
>> being overcharged.
>
> Nope, I strongly disagree. Holding a Li-Ion battery at 4.2 volts per
> cell will kill them in about 2 years (even if you have never drained
> them). Holding them at 4.1 volts per cell, they will last 3 to 4 years or
> more. You call overcharging when they explode, while I call overcharging
> when damage is being done.
>

I'm afraid not. Floating a Li-ion cell across a 4.2 volt (+/- 0.5%) causes
the cell EMF to rise to very close to 4.2 volts. The cell then draws
current that more or less just balances the self discharge current. Reduce
the charging voltage by just 1% (4.16v) results in the battery being
undercharged by as much as 10% of its available capacity. However inceasing
the charge voltage by 1% results in the cell overcharging by 25% (and
potentially exploding).

> Li-Ion batteries likes being left alone. And they do best just sitting at
> between 40% to 50% of capacity doing absolutely nothing. Lazy beings they
> are. And they can enjoy life 10 years or more in this state.
>

Actually, Li-ion batteries hate sitting around doing nothing. However, as
you state, they do it best at a 40% charge level. The greatest number of
charge/discharge cycles is obtained by actually charging and discharging
them.

> I am sure heat isn't good them them in a hot laptop. But I have seen
> Li-Ion batteries left in laptops that were only used briefly about twice
> per year (for a few hours) and the rest of the time the laptops were off,
> While the AC kept the cells at 4.2 volts and it still killed the Li-Ion
> batteries. No heat was responsible here. It had to be the 4.2 volts that
> slowly killed them. There is no other reason that I can think of.
>

Some manufacturers rather than design a charging circuit with the required
accuracy (+/- 0.5%) prefer to build a circuit with a poorer accuracy (as
it's cheaper) and have a slightly lower aiming point so that the absolute
maximum permissible voltage of 4.221 volts isn't exceeded.

> There is also a discussion in:
>
> sci.chem.electrochem.battery
>
> That discusses this in detail.
>
> Oh and they want references of your claim that under voltage cells can
> explode. They have never heard of this. They stated that a small amount of
> current is always safe and fine to try to bring one back to life.
>

I didn't say anything about undervoltage cells exploding, The only issue is
if cells are discharged below around 3 volts (2.5 volts for some early
chemistries), where copper is plated out on the internal structure. this
gives rise to a short circuit path that by-passes the PTC protection.

We use rechargeable batteries in aerospace and military projects. We have
deliberately abused, overcharged and over discharged several Li-ion cells
and batteries to the point of them exploding for the purposes of determining
safety parameters for both use and carriage. We use batteries of several
types in UAV aircraft and are fully cognizant of all the characteristics and
limitations.

> And they also tell me that Li-Ion batteries once drops down to a low level
> between the plates (the voltage potential), they naturally open. And
> trying to recharge them won't change anything. But you and I believe there
> is a safety circuit that causes them to open within the pack. So who is
> right?
>

The battery monitor circuit should prevent charging of any cell whose EMF
has dropped below around 3.0 volts. However, some single cell batteries
rely on the host charging circuit to prevent such charging and it is
possible to resurect such a cell with a separate supply. There are
considerable hazards associated with this practice and many 'accidents' have
forced battery manufacturers to move the protection into the batteries
themselves.

"M.I.5¾" <no.one@no.where.NO_SPAM.co.uk> wrote in message
news:45588f7b$1_1@glkas0286.greenlnk.net
> "BillW50" <BillW50@aol.kom> wrote in message
> news:45588793$0$1350$834e42db@reader.greatnowhere. com...
>> Nope, I strongly disagree. Holding a Li-Ion battery at 4.2 volts per
>> cell will kill them in about 2 years (even if you have never drained
>> them). Holding them at 4.1 volts per cell, they will last 3 to 4
>> years or more. You call overcharging when they explode, while I call
>> overcharging when damage is being done.
>
> I'm afraid not. Floating a Li-ion cell across a 4.2 volt (+/- 0.5%)
> causes the cell EMF to rise to very close to 4.2 volts. The cell
> then draws current that more or less just balances the self discharge
> current. Reduce the charging voltage by just 1% (4.16v) results in
> the battery being undercharged by as much as 10% of its available
> capacity. However inceasing the charge voltage by 1% results in the
> cell overcharging by 25% (and potentially exploding).

I have seen older Li-Ion batteries that will not even hold 4.2v. And
putting them in the laptop, they never stop charging and if the laptop
is also on, gets very hot. If you leave it this state, they die off
really quickly. Pull them out and put them on the shelf, they could last
a few more years if you recharge them once again before the voltage
drops too low.

>> Li-Ion batteries likes being left alone. And they do best just
>> sitting at between 40% to 50% of capacity doing absolutely nothing.
>> Lazy beings they are. And they can enjoy life 10 years or more in
>> this state.
>
> Actually, Li-ion batteries hate sitting around doing nothing. However,
> as you state, they do it best at a 40% charge level. The
> greatest number of charge/discharge cycles is obtained by actually
> charging and discharging them.

I disagree. They last the longest this way. And budgie in the newsgroup
mention below has the same opinion. As well as manufactures and stores
too.

>> I am sure heat isn't good them them in a hot laptop. But I have seen
>> Li-Ion batteries left in laptops that were only used briefly about
>> twice per year (for a few hours) and the rest of the time the
>> laptops were off, While the AC kept the cells at 4.2 volts and it
>> still killed the Li-Ion batteries. No heat was responsible here. It
>> had to be the 4.2 volts that slowly killed them. There is no other
>> reason that I can think of.
>
> Some manufacturers rather than design a charging circuit with the
> required accuracy (+/- 0.5%) prefer to build a circuit with a poorer
> accuracy (as it's cheaper) and have a slightly lower aiming point so
> that the absolute maximum permissible voltage of 4.221 volts isn't
> exceeded.

That is fine with brand new cells, but bad when cells are less then new.
budgie claims that cells last 30% longer if only charging to 4.1v. I
believe he is off a bit as I think they last longer than that.

>> There is also a discussion in:
>>
>> sci.chem.electrochem.battery
>>
>> That discusses this in detail.
>>
>> Oh and they want references of your claim that under voltage cells
>> can explode. They have never heard of this. They stated that a small
>> amount of current is always safe and fine to try to bring one back
>> to life.
>
> I didn't say anything about undervoltage cells exploding, The only
> issue is if cells are discharged below around 3 volts (2.5 volts for
> some early chemistries), where copper is plated out on the internal
> structure. this gives rise to a short circuit path that by-passes
> the PTC protection.

I meant charging too low voltage cells exploding. budgie has never heard
of such a thing.

> We use rechargeable batteries in aerospace and military projects. We
> have deliberately abused, overcharged and over discharged several
> Li-ion cells and batteries to the point of them exploding for the
> purposes of determining safety parameters for both use and carriage.
> We use batteries of several types in UAV aircraft and are fully
> cognizant of all the characteristics and limitations.

Yes I understand we have different experiences. My start was with the
VTAS computer which was used in the Lunar Lander.

>> And they also tell me that Li-Ion batteries once drops down to a low
>> level between the plates (the voltage potential), they naturally
>> open. And trying to recharge them won't change anything. But you and
>> I believe there is a safety circuit that causes them to open within
>> the pack. So who is right?
>
> The battery monitor circuit should prevent charging of any cell whose
> EMF has dropped below around 3.0 volts. However, some single cell
> batteries rely on the host charging circuit to prevent such charging
> and it is possible to resurect such a cell with a separate supply.
> There are considerable hazards associated with this practice and many
> 'accidents' have forced battery manufacturers to move the protection
> into the batteries themselves.

As budgie felt and so do I, it should be perfectly safe to trickle
charge a Li-Ion battery to see if the charge will increase. If the
current is really low, there should be no danger whatsoever of any heat
being generated. Although my experience with both Pb and Li-Ion
batteries, if the voltage is too low and have been stored that way. It
probably isn't worth trying to save it.

--
Bill

"BillW50" <BillW50@aol.kom> wrote in message
news:45592540$0$1345$834e42db@reader.greatnowhere. com...
> "M.I.5¾" <no.one@no.where.NO_SPAM.co.uk> wrote in message
> news:45588f7b$1_1@glkas0286.greenlnk.net
>> "BillW50" <BillW50@aol.kom> wrote in message
>> news:45588793$0$1350$834e42db@reader.greatnowhere. com...
>>> Nope, I strongly disagree. Holding a Li-Ion battery at 4.2 volts per
>>> cell will kill them in about 2 years (even if you have never drained
>>> them). Holding them at 4.1 volts per cell, they will last 3 to 4
>>> years or more. You call overcharging when they explode, while I call
>>> overcharging when damage is being done.
>>
>> I'm afraid not. Floating a Li-ion cell across a 4.2 volt (+/- 0.5%)
>> causes the cell EMF to rise to very close to 4.2 volts. The cell
>> then draws current that more or less just balances the self discharge
>> current. Reduce the charging voltage by just 1% (4.16v) results in
>> the battery being undercharged by as much as 10% of its available
>> capacity. However inceasing the charge voltage by 1% results in the
>> cell overcharging by 25% (and potentially exploding).
>
> I have seen older Li-Ion batteries that will not even hold 4.2v. And
> putting them in the laptop, they never stop charging and if the laptop is
> also on, gets very hot. If you leave it this state, they die off really
> quickly. Pull them out and put them on the shelf, they could last a few
> more years if you recharge them once again before the voltage drops too
> low.
>

There is a failure mode of Li-ion cells where the top end EMF drops off. If
you are lucky the EMF will rise to the cut off point during charge and then
drop to a lower value when removed from charge. Strangely such cells can
deliver their full rated capacity. Unfortunately other cells can fail to
rise to the required voltage and terminate the charge. However the charge
monitor circuit should detect this condition and stop the charge before harm
is done. However some early circuits failed to implement this.

>>> Li-Ion batteries likes being left alone. And they do best just
>>> sitting at between 40% to 50% of capacity doing absolutely nothing.
>>> Lazy beings they are. And they can enjoy life 10 years or more in
>>> this state.
>>
>> Actually, Li-ion batteries hate sitting around doing nothing. However, as
>> you state, they do it best at a 40% charge level. The
>> greatest number of charge/discharge cycles is obtained by actually
>> charging and discharging them.
>
> I disagree. They last the longest this way. And budgie in the newsgroup
> mention below has the same opinion. As well as manufactures and stores
> too.
>

Unfortunately, manufacturers are surprisingly reluctant to put out full
information on their batteries. Much that is published, even in supposedly
authoratative literature, is often based on speculation and anecdotal
evidence. Some of the worst sources are supposed expert web sites.

The main problem is that the degradation process comes from three angles.
First, cells start to degrade the moment they roll of the production line.
The speed of degradation is dependant on residual charge and temperature,
but proceeds even for completely unused cells. Second, cells degrade with
use. A typical Li-ion cell is good for around 300-500C charge/discharge
cycles. Third, cells degrade with lack of use. Although this seems to
contradict the second one, the porous plates of the cell structure tend to
become less porous with lack of use and the cell capacity falls as a result.
None of the three effects is reversable. There is no method of determining
the optimal charge/dischare frequency because all of the effects are very
dependant on the excact method of construction of the cells. Manufacturers
vary considerably on this, even between different battery ranges. However,
if the battery isn't abused, it is quite possible to get the full 300-500
cycles over a period of over 10 years (this contradicts much of the 'expert'
information on many web sites).

>>> I am sure heat isn't good them them in a hot laptop. But I have seen
>>> Li-Ion batteries left in laptops that were only used briefly about
>>> twice per year (for a few hours) and the rest of the time the
>>> laptops were off, While the AC kept the cells at 4.2 volts and it
>>> still killed the Li-Ion batteries. No heat was responsible here. It
>>> had to be the 4.2 volts that slowly killed them. There is no other
>>> reason that I can think of.
>>
>> Some manufacturers rather than design a charging circuit with the
>> required accuracy (+/- 0.5%) prefer to build a circuit with a poorer
>> accuracy (as it's cheaper) and have a slightly lower aiming point so
>> that the absolute maximum permissible voltage of 4.221 volts isn't
>> exceeded.
>
> That is fine with brand new cells, but bad when cells are less then new.
> budgie claims that cells last 30% longer if only charging to 4.1v. I
> believe he is off a bit as I think they last longer than that.
>

As it happens, we cannot run an aerospace business on unqualified opinion.
We know he's wrong and that's the end of it.

>>> There is also a discussion in:
>>>
>>> sci.chem.electrochem.battery
>>>
>>> That discusses this in detail.
>>>
>>> Oh and they want references of your claim that under voltage cells
>>> can explode. They have never heard of this. They stated that a small
>>> amount of current is always safe and fine to try to bring one back
>>> to life.
>>
>> I didn't say anything about undervoltage cells exploding, The only
>> issue is if cells are discharged below around 3 volts (2.5 volts for
>> some early chemistries), where copper is plated out on the internal
>> structure. this gives rise to a short circuit path that by-passes
>> the PTC protection.
>
> I meant charging too low voltage cells exploding. budgie has never heard
> of such a thing.
>

WTF is this 'budgie'. The fact that he has never heard of it doesn't make
it so. What it does mean is that anyone following his advice is a complete
idiot. Especially with a technology as potentially dangerous as Lithium
batteries. They do explode and we have actually done it.

>> We use rechargeable batteries in aerospace and military projects. We
>> have deliberately abused, overcharged and over discharged several
>> Li-ion cells and batteries to the point of them exploding for the
>> purposes of determining safety parameters for both use and carriage. We
>> use batteries of several types in UAV aircraft and are fully
>> cognizant of all the characteristics and limitations.
>
> Yes I understand we have different experiences. My start was with the VTAS
> computer which was used in the Lunar Lander.
>
>>> And they also tell me that Li-Ion batteries once drops down to a low
>>> level between the plates (the voltage potential), they naturally
>>> open. And trying to recharge them won't change anything. But you and
>>> I believe there is a safety circuit that causes them to open within
>>> the pack. So who is right?
>>
>> The battery monitor circuit should prevent charging of any cell whose
>> EMF has dropped below around 3.0 volts. However, some single cell
>> batteries rely on the host charging circuit to prevent such charging
>> and it is possible to resurect such a cell with a separate supply. There
>> are considerable hazards associated with this practice and many
>> 'accidents' have forced battery manufacturers to move the protection
>> into the batteries themselves.
>
> As budgie felt and so do I, it should be perfectly safe to trickle charge
> a Li-Ion battery to see if the charge will increase. If the current is
> really low, there should be no danger whatsoever of any heat being
> generated. Although my experience with both Pb and Li-Ion batteries, if
> the voltage is too low and have been stored that way. It probably isn't
> worth trying to save it.
>

Your budgerigar's opinion is not fact. To deal with Lithium batteries
safely, you need facts not ill informed speculative and inaccurate opinion.

This discussion is not worth pursuing any further.

"M.I.5¾" <no.one@no.where.NO_SPAM.co.uk> wrote in message
news:4559772d_1@glkas0286.greenlnk.net

[snip]

> This discussion is not worth pursuing any further.

Sure it is. As it is just getting good! How are people going to learn
anything if we just claim up? Also I have a video too. So does your
exploding Li-Ion batteries look like this?

http://www.youtube.com/watch?v=WeWq6rWzChw&eurl=

--
Bill

"BillW50" <BillW50@aol.kom> wrote in message
news:455a0885$0$1347$834e42db@reader.greatnowhere. com...
> "M.I.5¾" <no.one@no.where.NO_SPAM.co.uk> wrote in message
> news:4559772d_1@glkas0286.greenlnk.net
>
> [snip]
>
>> This discussion is not worth pursuing any further.
>
> Sure it is. As it is just getting good! How are people going to learn
> anything if we just claim up? Also I have a video too. So does your
> exploding Li-Ion batteries look like this?
>
> http://www.youtube.com/watch?v=WeWq6rWzChw&eurl=
>

Couldn't tell you. youtube is blocked at my company's servers. I have lots
of film and video of exploding batteries (and not just Li-ion - Ni-Cd and
Ni-MH give a fairly impressive display as well). I can't post any of them
though.

"M.I.5¾" <no.one@no.where.NO_SPAM.co.uk> wrote in message
news:455c594c$1_1@glkas0286.greenlnk.net
> "BillW50" <BillW50@aol.kom> wrote in message
> news:455a0885$0$1347$834e42db@reader.greatnowhere. com...
>> "M.I.5¾" <no.one@no.where.NO_SPAM.co.uk> wrote in message
>> news:4559772d_1@glkas0286.greenlnk.net
>>
>> [snip]
>>
>>> This discussion is not worth pursuing any further.
>>
>> Sure it is. As it is just getting good! How are people going to learn
>> anything if we just claim up? Also I have a video too. So does your
>> exploding Li-Ion batteries look like this?
>>
>> http://www.youtube.com/watch?v=WeWq6rWzChw&eurl=
>
> Couldn't tell you. youtube is blocked at my company's servers. I
> have lots of film and video of exploding batteries (and not just
> Li-ion - Ni-Cd and Ni-MH give a fairly impressive display as well). I
> can't post any of them though.

You don't have your own net access? Like at home?

I've never seen Ni-Cd or Ni-Mh batteries ever explode. Well to be
honest, any battery type explode for that matter. But I don't doubt that
they do explode. As I have seen videos.

My dad leaves Ni-Mh AA batteries forever on an overnight Ni-Cd charger
that came with his very old digital camera. I am not a big believer in
leaving Ni-Mh or Li-Ion on a trickle charger. As I believe for my
experience that their life is much shorter when done this way. I haven't
made up my mind about keeping a trickle charge on Ni-Cd or lead-acid
batteries.

About 30 years ago, I did connect 10 AA Ni-Cd batteries in series
directly to a car cigarette lighter socket. At the time I figured it
would over charge them and ruin them, but it was an emergency. I
remember they got pretty warm and the seals must of blown, as they
didn't last too long after this.

My only experience with over charging Ni-Mh was with a 150ma charger for
a pack that had about the size of AAA batteries. And I quickly learned
that anything over an hour and 20 minutes the pack would get very hot
(batteries fully discharged before charging). So I quickly moved to
smart chargers. Or if this wasn't possible, to monitor the temperature
in dumb chargers.

One of my favorite AA and AAA Ni-Cd and Ni-Mh charger is the Rayovac
PS4. It is one of the few chargers which charges the cells independently
instead of in pairs. And they have this smart charger down to a science.
As I have measured temps over 140 degrees F, which is pretty hot for
Ni-Mh batteries. Coupled with hot plastic smells etc. But it hasn't
ruined a battery yet. Been using two of these chargers for about 2 years
now.

I use another smart charger from Tower Hobbies for all 4 battery types.
As you can program it for the current, time, temp, etc. You can even
discharge and charge in a cycle and it will read out the capacity of the
batteries. And for Ni-xx types you can even set the delta. The only
thing I don't like is that you can only dial in charging in 100ma steps.
Which is too high for very small cells like those 9v rechargeables.

--
Bill

"BillW50" <BillW50@aol.kom> wrote in message
news:457052a1$0$1348$834e42db@reader.greatnowhere. com...
> "M.I.5¾" <no.one@no.where.NO_SPAM.co.uk> wrote in message
> news:455c594c$1_1@glkas0286.greenlnk.net
>> "BillW50" <BillW50@aol.kom> wrote in message
>> news:455a0885$0$1347$834e42db@reader.greatnowhere. com...
>>> "M.I.5¾" <no.one@no.where.NO_SPAM.co.uk> wrote in message
>>> news:4559772d_1@glkas0286.greenlnk.net
>>>
>>> [snip]
>>>
>>>> This discussion is not worth pursuing any further.
>>>
>>> Sure it is. As it is just getting good! How are people going to learn
>>> anything if we just claim up? Also I have a video too. So does your
>>> exploding Li-Ion batteries look like this?
>>>
>>> http://www.youtube.com/watch?v=WeWq6rWzChw&eurl=
>>
>> Couldn't tell you. youtube is blocked at my company's servers. I
>> have lots of film and video of exploding batteries (and not just
>> Li-ion - Ni-Cd and Ni-MH give a fairly impressive display as well). I
>> can't post any of them though.
>
> You don't have your own net access? Like at home?
>
> I've never seen Ni-Cd or Ni-Mh batteries ever explode. Well to be honest,
> any battery type explode for that matter. But I don't doubt that they do
> explode. As I have seen videos.
>
> My dad leaves Ni-Mh AA batteries forever on an overnight Ni-Cd charger
> that came with his very old digital camera. I am not a big believer in
> leaving Ni-Mh or Li-Ion on a trickle charger. As I believe for my
> experience that their life is much shorter when done this way. I haven't
> made up my mind about keeping a trickle charge on Ni-Cd or lead-acid
> batteries.
>

Was it a trickle charger or an overnight charger. Anyway, it is not a good
idea. Once the batteries are charged, the current breaks the water conntent
down into Oxygen and Hydrogen. Although there is a catalyst to recombine
them, it is only good for a moderate overcharge. Once the water is gone the
batteries won't work anymore.

> About 30 years ago, I did connect 10 AA Ni-Cd batteries in series directly
> to a car cigarette lighter socket. At the time I figured it would over
> charge them and ruin them, but it was an emergency. I remember they got
> pretty warm and the seals must of blown, as they didn't last too long
> after this.
>

You were extremely lucky. This is one scenario where Ni-Cd batteries can
explode. They have a negative temperature coefficient. As they get warmer
the resistance falls causing the current to rise, the battery to get warmer,
the resistance to drop, the current to rise ... and so on. It is called
thermal runaway. It is the reason Ni-Cd batteries are not used for car
starting purposes. They would be the ideal battery, but the penny pinching
car manufacturers are too mean to pay for the extra charge controlling
circuitry that would be required.

> My only experience with over charging Ni-Mh was with a 150ma charger for a
> pack that had about the size of AAA batteries. And I quickly learned that
> anything over an hour and 20 minutes the pack would get very hot
> (batteries fully discharged before charging). So I quickly moved to smart
> chargers. Or if this wasn't possible, to monitor the temperature in dumb
> chargers.
>

Unlike Ni-Cd batteries, Ni-MH do get quite warm while charging. The charge
reaction is exothermic. There should always be a temperature monitor,
though cheap chargers rarely bother. The Ni-Cd charge reaction is
endothermic so the battery only starts to get warm once it is charged as the
thermal absorbtion roughly balances the heat produced by inefficiency (only
70% of the charge current actually charges the battery).