Twin battery charging question.

Hi All,

Daughter has been using an old Dell Latitude D520 for a year or so and
it has the main / std battery ... and came with one of the modular
bay batteries that is currently fitted.

I understand the main battery has been showing it's age (she's living
away from home now but is currently visiting) and as we speak, neither
battery seems to be charging (although the machine works fine under
mains power etc).

If I go into the BIOS it shows the main battery as 'Not present' and
the modular battery as there but very low in charge (3% or so).
Neither XP nor Linux can see the primary battery either
(unsurprisingly).

It has a real Dell charger and has been fine with everything as is for
over a year etc. [1]

On the basis we knew the main battery was on its way out I was
thinking of getting another one in any case (it mainly needs to be
used to cover the machine for moves between power sockets) and in the
hope that the charge control circuitry doesn't work if the main
battery isn't fitted (or has died in a weird way)?

Would the DC power socket have any part to play in this? It works
under mains power and whist the plug and socket have seen some work
they do seem ok (and I've changed a few in my time so can normally
feel a 'bad' one).

Cheers, T i m

[1] Remembering this setup has been working nearly daily for a good
while ... the charger / psu is a Dell (well, Liteon) PA-12 (DF263,
PA-160-06D3) and rated at 19.5V / 3.34A. On the bottom of the laptop
it says it requires a PA-10 or 12 adaptor, 19.5V but has a current
requirement of 4.62A?

Am I right in thinking this would just mean that (say) it had both
batteries in it wouldn't be able to charge them as fast as if it had
the full charger current ability available? ie, it wouldn't do any
harm as such? In the BIOS I think it also can't see the charger but
that is pretty commonplace from my experience.

In news:,
T i m typed on Tue, 18 Jan 2011 13:28:52 +0000:
> Hi All,
>
> Daughter has been using an old Dell Latitude D520 for a year or so and
> it has the main / std battery ... and came with one of the modular
> bay batteries that is currently fitted.
>
> I understand the main battery has been showing it's age (she's living
> away from home now but is currently visiting) and as we speak, neither
> battery seems to be charging (although the machine works fine under
> mains power etc).
>
> If I go into the BIOS it shows the main battery as 'Not present' and
> the modular battery as there but very low in charge (3% or so).
> Neither XP nor Linux can see the primary battery either
> (unsurprisingly).
>
> It has a real Dell charger and has been fine with everything as is for
> over a year etc. [1]
>
> On the basis we knew the main battery was on its way out I was
> thinking of getting another one in any case (it mainly needs to be
> used to cover the machine for moves between power sockets) and in the
> hope that the charge control circuitry doesn't work if the main
> battery isn't fitted (or has died in a weird way)?
>
> Would the DC power socket have any part to play in this? It works
> under mains power and whist the plug and socket have seen some work
> they do seem ok (and I've changed a few in my time so can normally
> feel a 'bad' one).
>
> Cheers, T i m
>
> [1] Remembering this setup has been working nearly daily for a good
> while ... the charger / psu is a Dell (well, Liteon) PA-12 (DF263,
> PA-160-06D3) and rated at 19.5V / 3.34A. On the bottom of the laptop
> it says it requires a PA-10 or 12 adaptor, 19.5V but has a current
> requirement of 4.62A?
>
> Am I right in thinking this would just mean that (say) it had both
> batteries in it wouldn't be able to charge them as fast as if it had
> the full charger current ability available? ie, it wouldn't do any
> harm as such? In the BIOS I think it also can't see the charger but
> that is pretty commonplace from my experience.

Well it is very clear that almost all laptops benefit from removing the
main battery if you are not using it. As the heat of the laptop alone
shortens the battery life. Plus most laptops are designed to keep each
lithium cell at 4.2v, which also shortens the battery life. This is true
for those with a second battery as well.

The second thing I see a lot is people keeping an almost shot battery
(and sometimes a completely useless one) in the laptop. This in my
experience is a very bad thing to do. As if the laptop battery still
charges a battery in this state, it throws all of the current into the
battery that it safely can. This is normally ok for a good battery, as
the current drops off right away as the battery starts taking a charge.

But a bad battery, this never happens. As it continues to supply a huge
amount of current for months if not years. And the circuits just can't
take this that long. Besides shortening the life of the battery, it can
ruin the charging circuits and even the AC power circuits. Meaning it
may never charge any battery ever again, or worse, never run from AC
ever again either.

All laptops that has a second battery works in this way AFAIK. This one
that I am on also has a second battery. And a laptop doesn't care which
battery it is getting its power from. So you can use only the main
battery if you want, or remove the main battery and just have the second
battery installed, or neither and just on AC alone.

The big plus for two batteries of course is much longer running time.
This one for example can run 10 hours alone from these two (virtually
unheard of for laptops). Plus as long as one still has a charge, you can
remove one battery and pop in another one while the laptop is still
running.

It sounds like though, your daughter just needs enough battery power to
go from one outlet to another. In that case, I would get either a new
main battery or a second battery and don't worry about the other one and
remove it. Of course, it is a gamble that none of the circuits have been
already damaged.

If this is too much of a gamble, the cheap way is just put the laptop in
hibernate mode, then switch to another outlet. I don't know, I think
this laptop takes 10 seconds to go in and out of hibernation with 2GB of
RAM installed. But my old ('99) Toshiba 2595XDVD laptops with 192MB of
RAM takes over 10 minutes to hibernate and to come back out. So your
mileage may vary.

--
Bill
Gateway M465e ('06 era) - Centrino Core2 Duo 1.83G - 2GB - Windows XP
SP3

On Tue, 18 Jan 2011 09:53:39 -0600, "BillW50" <> wrote:


>> Am I right in thinking this would just mean that (say) it had both
>> batteries in it wouldn't be able to charge them as fast as if it had
>> the full charger current ability available? ie, it wouldn't do any
>> harm as such? In the BIOS I think it also can't see the charger but
>> that is pretty commonplace from my experience.
>
>Well it is very clear that almost all laptops benefit from removing the
>main battery if you are not using it. As the heat of the laptop alone
>shortens the battery life.

Understood. However, there is the benefit to having the battery in
place all the time if you could either lose power via a power cut or
simply having the DC plug pulled out. Built in UPS etc.

> Plus most laptops are designed to keep each
>lithium cell at 4.2v, which also shortens the battery life. This is true
>for those with a second battery as well.

Ok.

Again, ok if you are using a laptop as a desktop replacement but not
if you are using it portably. If I need to take a laptop out or away
from power it's good\to know that it's fully charged and I'm not sure
a 'charged last week and disconnected' battery would still be on top
form?

Also (when using a laptop on yer lap) I'm not sure I like the feel or
idea of using a laptop with big holes underneath? Maybe if they made
dummy batteries to fill up the space (or store some bits .. like USB
cables <g>) then it might be better?
>
>The second thing I see a lot is people keeping an almost shot battery
>(and sometimes a completely useless one) in the laptop. This in my
>experience is a very bad thing to do.

Understood but see above.

> As if the laptop battery still
>charges a battery in this state, it throws all of the current into the
>battery that it safely can. This is normally ok for a good battery, as
>the current drops off right away as the battery starts taking a charge.

Understood.
>
>But a bad battery, this never happens. As it continues to supply a huge
>amount of current for months if not years.

But wouldn't that mean the battery would get very hot? If it was
/consuming/ energy it had no way of absorbing then wouldn't that
energy be converted to heat?

> And the circuits just can't
>take this that long.

Whilst I agree with your thinking and feel this is what may have
happened in many of the cases I've seen I'd like to think the
electronics and monitoring would deal with it in a more subtle way
than cooking themselves. ;-(

> Besides shortening the life of the battery, it can
>ruin the charging circuits and even the AC power circuits. Meaning it
>may never charge any battery ever again, or worse, never run from AC
>ever again either.

Understood. Having many a battery powered device, including many
electric RC models and even a full road going electric car I'm fairly
familiar with how easily batteries can go bad. However, by the same
voodoo I've got a set of Nicads in a radio I've been using for over 20
years now. Also, I've just dug out an old Thinkpad R31 and after the
first charge for probably at least a year it's just run flat after 2.5
hours. The battery on one of the few machines I've ever bought from
new (the Asus eeePC 701) goes flat from full if left for more that a
couple of weeks.
>
>All laptops that has a second battery works in this way AFAIK. This one
>that I am on also has a second battery. And a laptop doesn't care which
>battery it is getting its power from. So you can use only the main
>battery if you want, or remove the main battery and just have the second
>battery installed, or neither and just on AC alone.

That I understand, with working batteries etc, but what if say the
primary battery goes bad. Is it required to be in place and working to
allow (say) the modular / second battery in this Dell to be charged?
>
>The big plus for two batteries of course is much longer running time.
>This one for example can run 10 hours alone from these two (virtually
>unheard of for laptops).

I think this Dell gave about 5 hours on both batteries when we first
got it and she does tend to use it from the battery initially at least
(if she knows she's going to be in a location for a while she'll plug
it in, if not she'll run from battery.

> Plus as long as one still has a charge, you can
>remove one battery and pop in another one while the laptop is still
>running.

Ok.
>
>It sounds like though, your daughter just needs enough battery power to
>go from one outlet to another.

Often but not always. ;-)

> In that case, I would get either a new
>main battery or a second battery and don't worry about the other one and
>remove it. Of course, it is a gamble that none of the circuits have been
>already damaged.

Exactly (and an advantage to having another machine with the same
battery as I have with 3 old Compaqs).
>
>If this is too much of a gamble,

Well, it wouldn't be the end of the world as it could be re-sold on
eBay if it turns out to be the worst and we don't find a replacement
systemboard at the right price.

> the cheap way is just put the laptop in
>hibernate mode, then switch to another outlet.

Or shut it down (it's pretty quick to start and she isn't bothered
either way).

> I don't know, I think
>this laptop takes 10 seconds to go in and out of hibernation with 2GB of
>RAM installed. But my old ('99) Toshiba 2595XDVD laptops with 192MB of
>RAM takes over 10 minutes to hibernate and to come back out. So your
>mileage may vary.

I have asked her several times if she's happy with her old Dell or
(considering what's happened to it of late) if she would like
something new(/er) and it seems she quite happy with her old Dell (CD
T2300, 1.66, 1G, 250G). ;-)

I did offer her this R31 Thinkpad I'm sorting out but she likes a
trackpad (and I think I prefer one also).

Cheers, T i m

In news:,
T i m typed on Tue, 18 Jan 2011 18:28:34 +0000:
> On Tue, 18 Jan 2011 09:53:39 -0600, "BillW50" <> wrote:
>
>
>>> Am I right in thinking this would just mean that (say) it had both
>>> batteries in it wouldn't be able to charge them as fast as if it had
>>> the full charger current ability available? ie, it wouldn't do any
>>> harm as such? In the BIOS I think it also can't see the charger but
>>> that is pretty commonplace from my experience.
>>
>> Well it is very clear that almost all laptops benefit from removing
>> the main battery if you are not using it. As the heat of the laptop
>> alone shortens the battery life.
>
> Understood. However, there is the benefit to having the battery in
> place all the time if you could either lose power via a power cut or
> simply having the DC plug pulled out. Built in UPS etc.

Yes of course, that is the only reason to have a battery installed if
used mostly on AC. Although depending on the cost of the battery (I can
get ones for mine for about 40 bucks), a real UPS can be cheaper. Plus
you can run more than a laptop from them as well.

Laptop batteries left in generally only last 2 to 3 years. While left
out, can last 10 years or more. And a real UPS, the battery generally
last 5 to 10 years running 24/7.

>> Plus most laptops are designed to keep each
>> lithium cell at 4.2v, which also shortens the battery life. This is
>> true for those with a second battery as well.
>
> Ok.

They push it to 4.2v per cell so they can claim longer running time. But
at a lost of battery longevity.

> Again, ok if you are using a laptop as a desktop replacement but not
> if you are using it portably. If I need to take a laptop out or away
> from power it's good\to know that it's fully charged and I'm not sure
> a 'charged last week and disconnected' battery would still be on top
> form?

Lithiums lose 2% of the charge per month. So a charge battery sitting
for a month should only lose 2% of its capacity.

> Also (when using a laptop on yer lap) I'm not sure I like the feel or
> idea of using a laptop with big holes underneath? Maybe if they made
> dummy batteries to fill up the space (or store some bits .. like USB
> cables <g>) then it might be better?

Sometimes you can find blanks that fill up the holes. This laptop I have
here they make one for. Although I cut a piece of wood with slots and
everything and it works just fine. This one needs something there to
trip the trigger for the port replicator.

Although normally the hole shouldn't be a problem. The only thing that
should be in there are the battery connections. And nothing dangerous
should be there if there is no battery anyway. Although I wouldn't take
a coin and short the connectors out. So not poking metal in there and
you should be okay.

>> The second thing I see a lot is people keeping an almost shot battery
>> (and sometimes a completely useless one) in the laptop. This in my
>> experience is a very bad thing to do.
>
> Understood but see above.
>
>> As if the laptop battery still
>> charges a battery in this state, it throws all of the current into
>> the battery that it safely can. This is normally ok for a good
>> battery, as the current drops off right away as the battery starts
>> taking a charge.
>
> Understood.
>>
>> But a bad battery, this never happens. As it continues to supply a
>> huge amount of current for months if not years.
>
> But wouldn't that mean the battery would get very hot? If it was
> /consuming/ energy it had no way of absorbing then wouldn't that
> energy be converted to heat?

They do, but the laptop itself also acts like a huge heat sink. So in a
way, that is the good news. The bad news is the circuits are pushing the
maximum they were designed to handle. That is okay short term, but not
if 24/7.

>> And the circuits just can't
>> take this that long.
>
> Whilst I agree with your thinking and feel this is what may have
> happened in many of the cases I've seen I'd like to think the
> electronics and monitoring would deal with it in a more subtle way
> than cooking themselves. ;-(

Well you would think, but most of the safety focus is keeping the
lithium battery from bursting into flames. And just worrying about that
is tricky enough. Plus I think manufactures wants to make extra money on
the batteries they can sell you anyway.

>> Besides shortening the life of the battery, it can
>> ruin the charging circuits and even the AC power circuits. Meaning it
>> may never charge any battery ever again, or worse, never run from AC
>> ever again either.
>
> Understood. Having many a battery powered device, including many
> electric RC models and even a full road going electric car I'm fairly
> familiar with how easily batteries can go bad.

I too use RC stuff. Although I mainly focus on flying RC. And things are
different there. As they have to be light enough to get off of the
ground, yet heavy enough to have longer flight times. Both are in total
opposition of each other.

> However, by the same voodoo I've got a set of Nicads in a radio I've
> been using for over 20 years now.

Ni-Cads are totally different than lithium. Care and feeding are totally
different too. And Ni-Cads are really safe as far as rechargeable
batteries goes. Although in about 7 years of time they generally develop
whiskers (which short them out). Can happen much earlier if you say to
charge them backwards or so. By the way I have some Ni-Cads that are
over 35 years old. Although I never had one this age that has any amount
of capacity to brag about.

And I am sure you heard of recycling the battery is good for them. For
Ni-Cads, this is really true. For other types including Ni-MH, lithium,
and lead-acid, it offers little to no help. Although it is a good thing
to do to learn the true capacity of a battery (of any type).

Both Ni-Cad and Ni-MH it seems somewhat okay to let them sit on the
shelf and let them drop to 0 volts. Not the best of course, but they can
usually bounce right back. Lead-acid can drop to half of the voltage and
if you recharge them within 24 hours, they seem to be able to take it
too. Longer they might be able to take it, but capacity starts to drop
off.

Lithium though, somewhere around 3.2 volts per cell and if you try to
recharge, you could have it burst into flames. They are very dangerous
as far as rechargeable battery go. As charging with too low of a
voltage, overcharging, and too many amps can cause it to burst into
flames. No other battery type is all this bad.

> Also, I've just dug out an old Thinkpad R31 and after the
> first charge for probably at least a year it's just run flat after 2.5
> hours.

Sounds like a lithium battery. They only lose 2% per month which means
they can last 50 months or over 4 years just sitting on the shelf.
Although I won't let a lithium sit longer than 2 years without a
recharge.

> The battery on one of the few machines I've ever bought from
> new (the Asus eeePC 701) goes flat from full if left for more that a
> couple of weeks.

Yes I too have 701s and 702s. That has nothing to do with the battery,
but because the Celeron CPU doesn't totally shutdown (or some supporting
circuits anyway). So it still uses power even when it is off. Although I
have to run some more tests, but if you remove the battery briefly after
shutdown, I think the drain problem is gone.

>> All laptops that has a second battery works in this way AFAIK. This
>> one that I am on also has a second battery. And a laptop doesn't
>> care which battery it is getting its power from. So you can use only
>> the main battery if you want, or remove the main battery and just
>> have the second battery installed, or neither and just on AC alone.
>
> That I understand, with working batteries etc, but what if say the
> primary battery goes bad. Is it required to be in place and working to
> allow (say) the modular / second battery in this Dell to be charged?

Well I don't have that Dell model, but generally speaking... you should
be able to remove the main battery and just use the second battery as
your main battery. Most laptops don't care which one is installed or
not.

>> The big plus for two batteries of course is much longer running time.
>> This one for example can run 10 hours alone from these two (virtually
>> unheard of for laptops).
>
> I think this Dell gave about 5 hours on both batteries when we first
> got it and she does tend to use it from the battery initially at least
> (if she knows she's going to be in a location for a while she'll plug
> it in, if not she'll run from battery.

That is why we use batteries in laptops for the most part. And while you
can often read lithium can be recharged up to 500 times, I find this
conservative. As I would agree if you only allow it to get down to 50%
capacity and recharge, you might get 500 recharges out of them.

Although if you use the full capacity say 5 times a week, you would be
lucky to get 6 months or 150 recharges out of them. So if you use it a
lot, the worry about it being gone after 2 or 3 years doesn't matter
much. In that case, go ahead and leave it in the laptop as it won't make
it that long anyway.

>> Plus as long as one still has a charge, you can
>> remove one battery and pop in another one while the laptop is still
>> running.
>
> Ok.
>>
>> It sounds like though, your daughter just needs enough battery power
>> to go from one outlet to another.
>
> Often but not always. ;-)

Then a small capacity battery is the way to go. But using an almost dead
battery (anything less than say 30 minutes of running time) would be a
mistake IMHO.

>> In that case, I would get either a new
>> main battery or a second battery and don't worry about the other one
>> and remove it. Of course, it is a gamble that none of the circuits
>> have been already damaged.
>
> Exactly (and an advantage to having another machine with the same
> battery as I have with 3 old Compaqs).

Yup that is what I do too. As I have three Gateway MX6124 and three
Gateway M465e and they all use the same batteries and almost all of the
same parts. And my three working EeePCs also use the same batteries and
I have five of them.

>> If this is too much of a gamble,
>
> Well, it wouldn't be the end of the world as it could be re-sold on
> eBay if it turns out to be the worst and we don't find a replacement
> systemboard at the right price.

True!

>> the cheap way is just put the laptop in
>> hibernate mode, then switch to another outlet.
>
> Or shut it down (it's pretty quick to start and she isn't bothered
> either way).

Yes that works too if the reboot times are short enough.

>> I don't know, I think
>> this laptop takes 10 seconds to go in and out of hibernation with
>> 2GB of RAM installed. But my old ('99) Toshiba 2595XDVD laptops with
>> 192MB of RAM takes over 10 minutes to hibernate and to come back
>> out. So your mileage may vary.
>
> I have asked her several times if she's happy with her old Dell or
> (considering what's happened to it of late) if she would like
> something new(/er) and it seems she quite happy with her old Dell (CD
> T2300, 1.66, 1G, 250G). ;-)

I don't know what she does, but that is generally a very respectable
machine.

> I did offer her this R31 Thinkpad I'm sorting out but she likes a
> trackpad (and I think I prefer one also).

Oh yes and I can see why. ;-)

--
Bill
Gateway M465e ('06 era)
Centrino Core2 Duo 1.83G - 2GB - Windows XP SP3

On Tue, 18 Jan 2011 14:21:44 -0600, "BillW50" <> wrote:

>> Understood. However, there is the benefit to having the battery in
>> place all the time if you could either lose power via a power cut or
>> simply having the DC plug pulled out. Built in UPS etc.
>
>Yes of course, that is the only reason to have a battery installed if
>used mostly on AC.

Other than for the UPS function (if you don't want to /also/ carry a
UPS about with you). ;-)

> Although depending on the cost of the battery (I can
>get ones for mine for about 40 bucks), a real UPS can be cheaper. Plus
>you can run more than a laptop from them as well.

Indeed.
>
>Laptop batteries left in generally only last 2 to 3 years. While left
>out, can last 10 years or more. And a real UPS, the battery generally
>last 5 to 10 years running 24/7.

And needs a sack barrow to move it. ;-)
>
>Lithiums lose 2% of the charge per month. So a charge battery sitting
>for a month should only lose 2% of its capacity.

Ok.
>
>> Also (when using a laptop on yer lap) I'm not sure I like the feel or
>> idea of using a laptop with big holes underneath? Maybe if they made
>> dummy batteries to fill up the space (or store some bits .. like USB
>> cables <g>) then it might be better?
>
>Sometimes you can find blanks that fill up the holes.

Oh, not seen one of them though have (once) made my own from an old
battery.

> This laptop I have
>here they make one for. Although I cut a piece of wood with slots and
>everything and it works just fine. This one needs something there to
>trip the trigger for the port replicator.

Ah yes.
>
>Although normally the hole shouldn't be a problem. The only thing that
>should be in there are the battery connections. And nothing dangerous
>should be there if there is no battery anyway. Although I wouldn't take
>a coin and short the connectors out. So not poking metal in there and
>you should be okay.

Sure and I wasn't worried about that as such. It was more the
discomfort of having a laptop on yer lap with a big hole and or sharp
edge / unstable mass etc. As you say though, all that could be worth
it to preserve the battery. Or you just treat them as a consumable as
long as they are cheap and don't do any damage to the system as they
age.
>
<snip>
>>
>> But wouldn't that mean the battery would get very hot? If it was
>> /consuming/ energy it had no way of absorbing then wouldn't that
>> energy be converted to heat?
>
>They do, but the laptop itself also acts like a huge heat sink.

Aren't the batteries in their own plastic case and further outside the
plastic case of the laptop itself (with an insulating air-gap etc)?

FWIW I left the T22 Thinkpad on charge (with it's very low capacity
battery) overnight and it ran cold.

> So in a
>way, that is the good news. The bad news is the circuits are pushing the
>maximum they were designed to handle. That is okay short term, but not
>if 24/7.

Understood.
>
>> Whilst I agree with your thinking and feel this is what may have
>> happened in many of the cases I've seen I'd like to think the
>> electronics and monitoring would deal with it in a more subtle way
>> than cooking themselves. ;-(
>
>Well you would think, but most of the safety focus is keeping the
>lithium battery from bursting into flames. And just worrying about that
>is tricky enough. Plus I think manufactures wants to make extra money on
>the batteries they can sell you anyway.

True.
>
>
>I too use RC stuff. Although I mainly focus on flying RC. And things are
>different there. As they have to be light enough to get off of the
>ground, yet heavy enough to have longer flight times. Both are in total
>opposition of each other.

Indeed. It is remarkable what they are doing with model flight now and
they are even racing full size electric motorbikes now I see! ;-)
>
>> However, by the same voodoo I've got a set of Nicads in a radio I've
>> been using for over 20 years now.
>
>Ni-Cads are totally different than lithium. Care and feeding are totally
>different too. And Ni-Cads are really safe as far as rechargeable
>batteries goes.

I've been present when quite a few have gone up, back in the early
days of RC 12th scale cars and charging via a resistor. ;-)

> Although in about 7 years of time they generally develop
>whiskers (which short them out). Can happen much earlier if you say to
>charge them backwards or so.

I've zapped a few like that back into life though (possibly not 'good'
but better than a dead battery).

> By the way I have some Ni-Cads that are
>over 35 years old.

Trumped! ;-(

>Although I never had one this age that has any amount
>of capacity to brag about.

Mine are a set of 4 7Ah 'D' cells. I think one is weak and so (as you
say) inevitably becomes weaker.

>And I am sure you heard of recycling the battery is good for them. For
>Ni-Cads, this is really true.

I have a discharge -> charger for the bigger cells (with a mAh
readout) and a 'reconditioner' for AAA and AA cells that charges /
discharges up to 4 cells (independently) till they reach a peak
capacity value. If nothing else it's enabled me to weed out some of
the bad cells and compare different brands of supposedly similar cells
/ types.

> For other types including Ni-MH, lithium,
>and lead-acid, it offers little to no help. Although it is a good thing
>to do to learn the true capacity of a battery (of any type).

Yup (see above).
>
>Both Ni-Cad and Ni-MH it seems somewhat okay to let them sit on the
>shelf and let them drop to 0 volts. Not the best of course, but they can
>usually bounce right back.

I've seen some very low voltage sells come back from the brink.

>Lead-acid can drop to half of the voltage and
>if you recharge them within 24 hours, they seem to be able to take it
>too. Longer they might be able to take it, but capacity starts to drop
>off.

I have a calcium construction battery in the kitcar and that seems to
be more resilient to prolonged over discharge than most other
batteries I've had.
>
>Lithium though, somewhere around 3.2 volts per cell and if you try to
>recharge, you could have it burst into flames. They are very dangerous
>as far as rechargeable battery go.

And they don't like being rammed with a fork-lift when on a pallet.
;-(

> As charging with too low of a
>voltage, overcharging, and too many amps can cause it to burst into
>flames. No other battery type is all this bad.

Just as well by the sound of it.
>
>> Also, I've just dug out an old Thinkpad R31 and after the
>> first charge for probably at least a year it's just run flat after 2.5
>> hours.
>
>Sounds like a lithium battery.

<Checks> Ni-MH.

> They only lose 2% per month which means
>they can last 50 months or over 4 years just sitting on the shelf.
>Although I won't let a lithium sit longer than 2 years without a
>recharge.

Ok.
>
>> The battery on one of the few machines I've ever bought from
>> new (the Asus eeePC 701) goes flat from full if left for more that a
>> couple of weeks.
>
>Yes I too have 701s and 702s. That has nothing to do with the battery,
>but because the Celeron

(mine is Atom powered (Does that count as a Celeron?)

> CPU doesn't totally shutdown (or some supporting
>circuits anyway). So it still uses power even when it is off.

Ah, that makes sense and now you mentioned I did leave the batter out
for a test and /think/ it was ok (or much better).

>Although I
>have to run some more tests, but if you remove the battery briefly after
>shutdown, I think the drain problem is gone.

Will do.
>

>> That I understand, with working batteries etc, but what if say the
>> primary battery goes bad. Is it required to be in place and working to
>> allow (say) the modular / second battery in this Dell to be charged?
>
>Well I don't have that Dell model, but generally speaking... you should
>be able to remove the main battery and just use the second battery as
>your main battery. Most laptops don't care which one is installed or
>not.

That would be my hope bit if it is then I might have a bigger problem.
>
>> I think this Dell gave about 5 hours on both batteries when we first
>> got it and she does tend to use it from the battery initially at least
>> (if she knows she's going to be in a location for a while she'll plug
>> it in, if not she'll run from battery.
>
>That is why we use batteries in laptops for the most part.

Well there are some who use their kit only on the move ... like when
commuting etc.

> And while you
>can often read lithium can be recharged up to 500 times, I find this
>conservative. As I would agree if you only allow it to get down to 50%
>capacity and recharge, you might get 500 recharges out of them.

Ah.
>
>Although if you use the full capacity say 5 times a week, you would be
>lucky to get 6 months or 150 recharges out of them. So if you use it a
>lot, the worry about it being gone after 2 or 3 years doesn't matter
>much. In that case, go ahead and leave it in the laptop as it won't make
>it that long anyway.

True. ;-)
>
>>> It sounds like though, your daughter just needs enough battery power
>>> to go from one outlet to another.
>>
>> Often but not always. ;-)
>
>Then a small capacity battery is the way to go. But using an almost dead
>battery (anything less than say 30 minutes of running time) would be a
>mistake IMHO.

Understood. I've ordered one from eBay tonight so we will see.
>
>> Exactly (and an advantage to having another machine with the same
>> battery as I have with 3 old Compaqs).
>
>Yup that is what I do too. As I have three Gateway MX6124 and three
>Gateway M465e and they all use the same batteries and almost all of the
>same parts. And my three working EeePCs also use the same batteries and
>I have five of them.

And I thought I was bad! ;-)
>
>>> If this is too much of a gamble,
>>
>> Well, it wouldn't be the end of the world as it could be re-sold on
>> eBay if it turns out to be the worst and we don't find a replacement
>> systemboard at the right price.
>
>True!

I think I would find another D520 as it does seem a nice machine.
Summat with a broken screen maybe.
>
>> I have asked her several times if she's happy with her old Dell or
>> (considering what's happened to it of late) if she would like
>> something new(/er) and it seems she quite happy with her old Dell (CD
>> T2300, 1.66, 1G, 250G). ;-)
>
>I don't know what she does, but that is generally a very respectable
>machine.

Nothing really demanding but like most kids doesn't like to have to
wait. I think it's mainly multitasking (or the task switching) than
any one thing. For games she tends to use her desktop.
>
>> I did offer her this R31 Thinkpad I'm sorting out but she likes a
>> trackpad (and I think I prefer one also).
>
>Oh yes and I can see why. ;-)

Again, I think you can get used to them and for some things they feel
better. Still not my preference though.

Cheers, T i m

In news:,
T i m typed on Wed, 19 Jan 2011 00:58:49 +0000:
> On Tue, 18 Jan 2011 14:21:44 -0600, "BillW50" <> wrote:

<snip>

>> They do, but the laptop itself also acts like a huge heat sink.
>
> Aren't the batteries in their own plastic case and further outside
> then't drawing the plastic case of the laptop itself (with an
> insulating air-gap etc)?

Yes, although it isn't perfect and it still does transfer some of the
heat.

> FWIW I left the T22 Thinkpad on charge (with it's very low capacity
> battery) overnight and it ran cold.

Most of them do. Although there isn't enough heat to feel because the
computer is off and it isn't drawing the maximum amount of current to do
both jobs at once.

<snip>

>> Ni-Cads are totally different than lithium. Care and feeding are
>> totally different too. And Ni-Cads are really safe as far as
>> rechargeable batteries goes.
>
> I've been present when quite a few have gone up, back in the early
> days of RC 12th scale cars and charging via a resistor. ;-)

Charging which type by resistor, Ni-Cads?

>> Although in about 7 years of time they generally develop
>> whiskers (which short them out). Can happen much earlier if you say
>> to charge them backwards or so.
>
> I've zapped a few like that back into life though (possibly not 'good'
> but better than a dead battery).

Yes I use to do that too. But I often found that once that happens, they
generally don't have much of a lifespan after that anyway. Maybe you can
get another year or two out of them in my experience.

>> By the way I have some Ni-Cads that are
>> over 35 years old.
>
> Trumped! ;-(

Well don't get too excited! As about 95% of all of the originals have
long bit the dust and only a few of them made it this long. Plus the
ones I have this long can't even run a flashlight more than a few
seconds.

>> Although I never had one this age that has any amount
>> of capacity to brag about.
>
> Mine are a set of 4 7Ah 'D' cells. I think one is weak and so (as you
> say) inevitably becomes weaker.
>
>> And I am sure you heard of recycling the battery is good for them.
>> For Ni-Cads, this is really true.
>
> I have a discharge -> charger for the bigger cells (with a mAh
> readout) and a 'reconditioner' for AAA and AA cells that charges /
> discharges up to 4 cells (independently) till they reach a peak
> capacity value. If nothing else it's enabled me to weed out some of
> the bad cells and compare different brands of supposedly similar cells
> / types.

Yes. And this is the one I have. Although I have the earlier v1.

http://www.electrifly.com/chargers/gpmm3153.html

>> For other types including Ni-MH, lithium,
>> and lead-acid, it offers little to no help. Although it is a good
>> thing to do to learn the true capacity of a battery (of any type).
>
> Yup (see above).
>>
>> Both Ni-Cad and Ni-MH it seems somewhat okay to let them sit on the
>> shelf and let them drop to 0 volts. Not the best of course, but they
>> can usually bounce right back.
>
> I've seen some very low voltage sells come back from the brink.
>
>> Lead-acid can drop to half of the voltage and
>> if you recharge them within 24 hours, they seem to be able to take it
>> too. Longer they might be able to take it, but capacity starts to
>> drop off.
>
> I have a calcium construction battery in the kitcar and that seems to
> be more resilient to prolonged over discharge than most other
> batteries I've had.

Oh wow!

>> Lithium though, somewhere around 3.2 volts per cell and if you try to
>> recharge, you could have it burst into flames. They are very
>> dangerous as far as rechargeable battery go.
>
> And they don't like being rammed with a fork-lift when on a pallet.
> ;-(

Oh you have seen this happen?

>> As charging with too low of a
>> voltage, overcharging, and too many amps can cause it to burst into
>> flames. No other battery type is all this bad.
>
> Just as well by the sound of it.
>>
>>> Also, I've just dug out an old Thinkpad R31 and after the
>>> first charge for probably at least a year it's just run flat after
>>> 2.5 hours.
>>
>> Sounds like a lithium battery.
>
> <Checks> Ni-MH.

Oh fascinating! ;-)

<snip>

>> Yes I too have 701s and 702s. That has nothing to do with the
>> battery, but because the Celeron
>
> (mine is Atom powered (Does that count as a Celeron?)

Are you sure? As all 700 series and just the 900 model should all have a
Celeron 900MHz. With the exception of the 700 which has a Celeron 800MHz
I believe.

>> CPU doesn't totally shutdown (or some supporting
>> circuits anyway). So it still uses power even when it is off.
>
> Ah, that makes sense and now you mentioned I did leave the batter out
> for a test and /think/ it was ok (or much better).
>
>> Although I
>> have to run some more tests, but if you remove the battery briefly
>> after shutdown, I think the drain problem is gone.
>
> Will do.

Let me know how that works out and I'll confirm with my tests. ;-)

<snip>

>>> Exactly (and an advantage to having another machine with the same
>>> battery as I have with 3 old Compaqs).
>>
>> Yup that is what I do too. As I have three Gateway MX6124 and three
>> Gateway M465e and they all use the same batteries and almost all of
>> the same parts. And my three working EeePCs also use the same
>> batteries and I have five of them.
>
> And I thought I was bad! ;-)

Yeah well... lots of companies and individuals like to brag how well
their computer service is (which usually cost megabucks). But it is
funny, say something terrible happened to this machine. I can swap say
this hard drive in another like machine and I am back up in less than a
minute. If the hard drive fails, well one machine has the last backup
anyway. Sure beats calling somebody or handing your computer to somebody
else, eh?

--
Bill
Gateway M465e ('06 era)
Centrino Core2 Duo 1.83G - 2GB - Windows XP SP3

On Thu, 20 Jan 2011 17:01:08 -0600, "BillW50" <> wrote:

<snip>

>>> Ni-Cads are totally different than lithium. Care and feeding are
>>> totally different too. And Ni-Cads are really safe as far as
>>> rechargeable batteries goes.
>>
>> I've been present when quite a few have gone up, back in the early
>> days of RC 12th scale cars and charging via a resistor. ;-)
>
>Charging which type by resistor, Ni-Cads?

Yup. Most of the early RC electric car kits came with a ww resistor
screwed to a bit of ally plate as a heatsink. I put my resistor in an
ally box along with a clockwork electrical timer / switch as my memory
was bad even then! What was amazing was what punishment the cells took
in even the early days, running 10 min race and then going straight on
charge (as most of us didn't have a second battery and they were
'built-in' in any case) and doing that all evening.
>
<snip>
>
>Well don't get too excited! As about 95% of all of the originals have
>long bit the dust and only a few of them made it this long. Plus the
>ones I have this long can't even run a flashlight more than a few
>seconds.

My big 'Ds' still run the radio ok but we will see in 10 years time.
;-)
>
<snip>

>Yes. And this is the one I have. Although I have the earlier v1.
>
>http://www.electrifly.com/chargers/gpmm3153.html

That looks pretty snazzy.

When I was racing electrathon machines I would borrow a batch of car
batteries for the weekend then cycle them whilst monitoring them with
a DMM and plotting the results on graph paper (with an alarm / timer
to remind me to take the measurements). Then I could pick the best
matched pair to race with for the season. ;-)
>
<snip>

>> And they don't like being rammed with a fork-lift when on a pallet.
>> ;-(
>
>Oh you have seen this happen?

No but I read about it happening at an airport (I think it was) and
that caused quite a few companies to be very twitchy about shipping
the things (I bought a laptop battery from the States before I knew of
such restrictions and to get someone over there to get it from the
supplier and ship it privately).
>
<snip>

>>> Yes I too have 701s and 702s. That has nothing to do with the
>>> battery, but because the Celeron
>>
>> (mine is Atom powered (Does that count as a Celeron?)
>
>Are you sure? As all 700 series and just the 900 model should all have a
>Celeron 900MHz. With the exception of the 700 which has a Celeron 800MHz
>I believe.

Not sure no <checks> Doh! Celeron M 900Mhz. ;-0
>
<snip>
>>
>>> Although I
>>> have to run some more tests, but if you remove the battery briefly
>>> after shutdown, I think the drain problem is gone.
>
>Let me know how that works out and I'll confirm with my tests. ;-)

Will do.
>
<snip>
>>
>> And I thought I was bad! ;-)
>
>Yeah well... lots of companies and individuals like to brag how well
>their computer service is (which usually cost megabucks). But it is
>funny, say something terrible happened to this machine. I can swap say
>this hard drive in another like machine and I am back up in less than a
>minute. If the hard drive fails, well one machine has the last backup
>anyway. Sure beats calling somebody or handing your computer to somebody
>else, eh?

Yup and why I have always built my own desktops since my first IBM
PC-XP clone. Not only do you get more flexibility but each component
is warranted so you rarely have to take the whole box back (as you
say).

Talking of having spares ... I popped into my mates PC shop yesterday
to see if he had another model of Dell that might take Son In Laws
battery so we might be able to isolate why his just stopped charging
and started flashing the power LED as it does. Ironically he had the
exact same model in for repair but with a broken charging socket and a
flat battery so we couldn't test / prove much. However, nothing we did
made a difference so I think we might be able to rule out his charger
and battery, leaving possibly a broken DC socket?

The lad who was covering for my mate in the shop buys pallet loads of
laptops to repair / sell on so whilst not particularly technical has
quite a bit of field knowledge about a whole range of machines and
knows what is a common fault or how difficult a fix might be at a
glance (he told us SILs Dell was either a 1525 or 1545 before he
looked underneath .. and the do all look pretty similar these days (it
was a 1545). He suggested that the octagonal power jack had an outer,
an inner and a centre pin and if a particular combination of those get
broken off at the socket / board you can get charging but no power,
power but no charging or nothing etc etc. Does that sound plausible to
you? FWIW it does tally with when the fault started as it was his mum
tripping over the power cable and the plug being yanked out? ;-( [1]

He also added that those models were b"stards to strip as bits were
held in with plastic clips (that often snap) rather than screws etc.
;-(

Oh, while we were these I noticed a Compaq Evo N400c on a dock in a
pile of old laptops. I asked him about it and he reckoned it needed a
new inverter and DC socket but he couldn't be bothered and would stick
it on eBay as-was. He said he'd only get 15 quid for it but as I'd
already got one I gave him the 15 quid and brought it home. With a
charged battery and on an external monitor it works ok so that's a
start. ;-)

I'll order a new DC socket off eBay and once fitted / working I'll
swap the displays between machines to make sure it /is/ a screen issue
(I just bought a spare / working display for my R31 Thinkpad but that
doesn't work either) . ;-(

Cheers, T i m

[1] About the only thing I like about the Apple laptops is the
'MagSafe' connector. ;-)

p.s. While I was looking for the Evo I dug out 'Old faithful' .. my
Dell Inspiron 8100! Now you know what you have that on yer lap! (I was
given it with no backlight and replaced the CCFL (fiddley / delicate
job) and I got it from the States for half the price I would have to
pay here).

On Jan 22, 4:02*am, T i m <n...@spaced.me.uk> wrote:
> On Thu, 20 Jan 2011 17:01:08 -0600, "BillW50" <Bill...@aol.kom> wrote:
>
> <snip>
>
> >>> Ni-Cads are totally different than lithium. Care and feeding are
> >>> totally different too. And Ni-Cads are really safe as far as
> >>> rechargeable batteries goes.
>
> >> I've been present when quite a few have gone up, back in the early
> >> days of RC 12th scale cars and charging via a resistor. ;-)
>
> >Charging which type by resistor, Ni-Cads?
>
> Yup. Most of the early RC electric car kits came with a ww resistor
> screwed to a bit of ally plate as a heatsink. I put my resistor in an
> ally box along with a clockwork electrical timer / switch as my memory
> was bad even then! What was amazing was what punishment the cells took
> in even the early days, running 10 min race and then going straight on
> charge (as most of us didn't have a second battery and they were
> 'built-in' in any case) and doing that all evening.
>
>
>
> <snip>
>
> >Well don't get too excited! As about 95% of all of the originals have
> >long bit the dust and only a few of them made it this long. Plus the
> >ones I have this long can't even run a flashlight more than a few
> >seconds.
>
> My big 'Ds' still run the radio ok but we will see in 10 years time.
> ;-)
>
> <snip>
>
> >Yes. And this is the one I have. Although I have the earlier v1.
>
> >http://www.electrifly.com/chargers/gpmm3153.html
>
> That looks pretty snazzy.
>
> When I was racing electrathon machines I would borrow a batch of car
> batteries for the weekend then cycle them whilst monitoring them with
> a DMM and plotting the results on graph paper (with an alarm / timer
> to remind me to take the measurements). Then I could pick the best
> matched pair to race with for the season. ;-)
>
> <snip>
>
> >> And they don't like being rammed with a fork-lift when on a pallet.
> >> ;-(
>
> >Oh you have seen this happen?
>
> No but I read about it happening at an airport (I think it was) and
> that caused quite a few companies to be very twitchy about shipping
> the things (I bought a laptop battery from the States before I knew of
> such restrictions and to get someone over there to get it from the
> supplier and ship it privately).
>
> <snip>
>
> >>> Yes I too have 701s and 702s. That has nothing to do with the
> >>> battery, but because the Celeron
>
> >> (mine is Atom powered (Does that count as a Celeron?)
>
> >Are you sure? As all 700 series and just the 900 model should all have a
> >Celeron 900MHz. With the exception of the 700 which has a Celeron 800MHz
> >I believe.
>
> Not sure no <checks> Doh! Celeron M 900Mhz. ;-0
>
>
>
> <snip>
>
> >>> Although I
> >>> have to run some more tests, but if you remove the battery briefly
> >>> after shutdown, I think the drain problem is gone.
>
> >Let me know how that works out and I'll confirm with my tests. ;-)
>
> Will do.
>
>
>
> <snip>
>
> >> And I thought I was bad! ;-)
>
> >Yeah well... lots of companies and individuals like to brag how well
> >their computer service is (which usually cost megabucks). But it is
> >funny, say something terrible happened to this machine. I can swap say
> >this hard drive in another like machine and I am back up in less than a
> >minute. If the hard drive fails, well one machine has the last backup
> >anyway. Sure beats calling somebody or handing your computer to somebody
> >else, eh?
>
> Yup and why I have always built my own desktops since my first IBM
> PC-XP clone. Not only do you get more flexibility but each component
> is warranted so you rarely have to take the whole box back (as you
> say).
>
> Talking of having spares ... I popped into my mates PC shop yesterday
> to see if he had another model of Dell that might take Son In Laws
> battery so we might be able to isolate why his just stopped charging
> and started flashing the power LED as it does. Ironically he had the
> exact same model in for repair but with a broken charging socket and a
> flat battery so we couldn't test / prove much. However, nothing we did
> made a difference so I think we might be able to rule out his charger
> and battery, leaving possibly a broken DC socket?
>
> The lad who was covering for my mate in the shop buys pallet loads of
> laptops to repair / sell on so whilst not particularly technical has
> quite a bit of field knowledge about a whole range of machines and
> knows what is a common fault or how difficult a fix might be at a
> glance (he told us SILs Dell was either a 1525 or 1545 before he
> looked underneath .. and the do all look pretty similar these days (it
> was a 1545). He suggested that the octagonal power jack had an outer,
> an inner and a centre pin and if a particular combination of those get
> broken off at the socket / board you can get charging but no power,
> power but no charging or nothing etc etc. Does that sound plausible to
> you? FWIW it does tally with when the fault started as it was his mum
> tripping over the power cable and the plug being yanked out? ;-( [1]
>
> He also added that those models were b"stards to strip as bits were
> held in with plastic clips (that often snap) rather than screws etc.
> ;-(
>
> Oh, while we were these I noticed a Compaq Evo N400c on a dock in a
> pile of old laptops. I asked him about it and he reckoned it needed a
> new inverter and DC socket but he couldn't be bothered and would stick
> it on eBay as-was. He said he'd only get 15 quid for it but as I'd
> already got one I gave him the 15 quid and brought it home. With a
> charged battery and on an external monitor it works ok so that's a
> start. ;-)
>
> I'll order a new DC socket off eBay and once fitted / working I'll
> swap the displays between machines to make sure it /is/ a screen issue
> (I just bought a spare / working display for my R31 Thinkpad but that
> doesn't work either) . ;-(
>
> Cheers, T i m
>
> [1] About the only thing I like about the Apple laptops is the
> 'MagSafe' connector. ;-)
>
> p.s. While I was looking for the Evo I dug out 'Old faithful' .. my
> Dell Inspiron 8100! Now you know what you have that on yer lap! (I was
> given it with no backlight and replaced the CCFL (fiddley / delicate
> job) and I got it from the States for half the price I would have to
> pay here).

Good God...maybe you guys should email! ;-p

On Sat, 22 Jan 2011 10:01:16 -0800 (PST), Bob Villa
<> wrote:

<big snip for Bob> ;-)
>
>Good God...maybe you guys should email! ;-p

Maybe, but it's /mostly/ about laptops ('n' batteries / electronics)
and it's not exactly buzzin on here atm eh?

Anyway, now you have read it all (ta), any practical suggestions re
our / my laptop woes please?

Cheers, T i m (going back to finding why anything later than Ubuntu
9.10 won't boot / run / show video (from a LiveCD) on my Dell Inspiron
8100 ... ) ;-(

On Jan 22, 6:01*pm, T i m <n...@spaced.me.uk> wrote:
> On Sat, 22 Jan 2011 10:01:16 -0800 (PST), Bob Villa
>
> <pheeh.z...@gmail.com> wrote:
>
> <big snip for Bob> ;-)
>
>
>
> >Good God...maybe you guys should email! ;-p
>
> Maybe, but it's /mostly/ about laptops ('n' batteries / electronics)
> and it's not exactly buzzin on here atm eh?
>
> Anyway, now you have read it all (ta), any practical suggestions re
> our / my laptop woes please?
>
> Cheers, T i m (going back to finding why anything later than Ubuntu
> 9.10 won't boot / run / show video (from a LiveCD) on my Dell Inspiron
> 8100 ... ) *;-(

No, I'm looking at replacing a Dell battery only a yr and a half old.
I've been warning the eldest daughter about suffocating her machine
for as long and I am ****ed. She will, at least, have to pay for half.

Take Care