Dell Laptop Battery Charging

[Juan Wei]

A friend has a Dell laptop that runs well except for one thing: it no
longer will charge the battery. It was suggested that he get a new
motherboard rather than attempt a repair. Is that the only possible
solution?

 

[VanguardLH]

A friend has a Dell laptop that runs well except for one thing: it no
longer will charge the battery. It was suggested that he get a new
motherboard rather than attempt a repair. Is that the only possible
solution?

How old is the battery? They need to get replaced after 3-4 years.

 

[Paul]

A friend has a Dell laptop that runs well except for one thing: it no
longer will charge the battery. It was suggested that he get a new
motherboard rather than attempt a repair. Is that the only possible
solution?

The BatteryUniversity site, goes into some detail about
the chemistry of laptop batteries, and why certain safety
features exist.

One of the features is, the charger will not charge
a battery pack when it drops below a certain voltage.
If you leave a battery sitting in a closet for five
years, it could be so close to "flat", that the laptop
charger circuit will refuse to charge it. The reason
for this, is some sort of conductive "whisker" can
form inside the battery, and short the battery out.
Laptop batteries catch fire if abused, so the safety
systems have to be pretty conservative.

So while you could hypothesize that the laptop charger
circuit is "broken", it's also possible the battery
is too flat to charge.

http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries

"Over-discharging Lithium-ion

Li-ion should never be discharged too low, and
there are several safeguards to prevent this from happening."

HTH,
Paul

 

[Juan Wei]

VanguardLH has written on 12/28/2013 10:57 PM:

How old is the battery? They need to get replaced after 3-4 years.

Not an issue. He has tried this with several batteries.

 

[Juan Wei]

Juan Wei has written on 12/28/2013 10:05 PM:

A friend has a Dell laptop that runs well except for one thing: it no
longer will charge the battery. It was suggested that he get a new
motherboard rather than attempt a repair. Is that the only possible
solution?

I should have mentioned this:

He has tried this with several batteries.

There is a message that says "Connected, not charging" for each of the
batteries.

 

[Paul]

Juan Wei has written on 12/28/2013 10:05 PM:

I should have mentioned this:

He has tried this with several batteries.

There is a message that says "Connected, not charging" for each of the
batteries.

If the laptop runs off the adapter, then the adapter is still
functioning to some extent.

The next logical place to look, after testing multiple
batteries, is the charging circuit on the motherboard.

*******

The battery has a fuel gauge. But the discussion here,
makes no mention of the fuel gauge, affecting the
behavior of the charging circuit. "Fuel information" is
there to help the user to decide what to do, like shutdown
or hibernate.

http://batteryuniversity.com/learn/article/the_battery_fuel_gauge

The charging circuit is "purely mechanical". It's behavior
is determined by the voltage and current flow information
it collects as it is charging the battery. On my laptop
at least, the charging circuit knows when to stop charging,
even when the CPU is shut down. So it doesn't appear to need
a CPU to manage it or anything. It knows when the current flow
tapers off during constant voltage charging, that the battery
is "full". The constant voltage is carefully selected.
Too low a voltage chosen, means less hours of runtime.
Too high a voltage, is a safety issue.

http://batteryuniversity.com/_img/content/ion1.jpg

The controls on a lithium charger are much more precise than
those on nickel cadmium, because for NiCd, the manufacturer
doesn't care if the electrolyte squirts out.

Paul

 

[Juan Wei]

Paul has written on 12/29/2013 11:14 AM:

If the laptop runs off the adapter, then the adapter is still
functioning to some extent.

To some extent? My impression is that the adapter feeds the motherboard
which in turn feeds the battery. So if the motherboard--i.e., the
computer--is working, then the adapter is fine.

The next logical place to look, after testing multiple
batteries, is the charging circuit on the motherboard.

*******

The battery has a fuel gauge. But the discussion here,
makes no mention of the fuel gauge, affecting the
behavior of the charging circuit. "Fuel information" is
there to help the user to decide what to do, like shutdown
or hibernate.

How does one access the fuel gauge?

http://batteryuniversity.com/learn/article/the_battery_fuel_gauge

The charging circuit is "purely mechanical". It's behavior
is determined by the voltage and current flow information
it collects as it is charging the battery. On my laptop
at least, the charging circuit knows when to stop charging,
even when the CPU is shut down. So it doesn't appear to need
a CPU to manage it or anything. It knows when the current flow
tapers off during constant voltage charging, that the battery
is "full". The constant voltage is carefully selected.
Too low a voltage chosen, means less hours of runtime.
Too high a voltage, is a safety issue.

Charging circuits are (or at least were) very simple things. You have a
source of (relatively) constant voltage at one end, something to limit
the current (may be a resistor to limit the amount and a diode to limit
the direction), and the battery to be charged at the other. As long as
the voltage at the source is greater than the voltage of the battery,
there will be a current. The amount of current is determined by Ohm's
Law: difference in voltage divided by resistance. So it's self-regulating.

Of course, real chargers are probably more sophisticated than that but
the principle is true.

So if the adapter is supplying voltage to the MB but not to the charging
ckt, it seems like there is a break in the charging ckt such that no
current can flow.

 

[Paul]

Charging circuits are (or at least were) very simple things. You have a
source of (relatively) constant voltage at one end, something to limit
the current (may be a resistor to limit the amount and a diode to limit
the direction), and the battery to be charged at the other. As long as
the voltage at the source is greater than the voltage of the battery,
there will be a current. The amount of current is determined by Ohm's
Law: difference in voltage divided by resistance. So it's self-regulating.

Of course, real chargers are probably more sophisticated than that but
the principle is true.

So if the adapter is supplying voltage to the MB but not to the charging
ckt, it seems like there is a break in the charging ckt such that no
current can flow.

If you have a weak adapter, pull the battery, and sit
idle in the desktop, you might be using 30% of the power
capacity of the battery. So if you're careful, you
can dream up a "light electrical load case" for testing
an adapter.

If you run Prime95 at the same time as you flip in a
battery and start charging it, now the adapter is
running closer to its 65W limit. In some cases, the
laptop may shut off - if it does, then the adapter
may be weak and need replacement. That's what I mean
when I say something demonstrates it is working "somewhat".
We don't know if the thing is 100% healthy, unless
making a test case with a good 100% electrical loading.

I have an ATX power supply here, that can run a single
cooling fan from the 12V rail (maybe 100 to 200ma). If
you draw more current than that, the 12V voltage drops
to out-of-range values. That's an example of an ATX supply
that "works" at no load (voltages in spec), but the supply
is of no use to me inside a computer. That's the supply
that came with my first PC. It's almost like the feedback
path inside the supply, no longer works.

******

http://batteryuniversity.com/_img/content/ion1.jpg

In the BatteryUniversity article, you can see the battery
charger runs in constant current mode in the beginning,
then switches to constant voltage mode, observing
the current flow until it has dropped to 3% of the
constant current value. The second phase of charging,
is the "topping up" phase. It brings the battery as
close as possible to full capacity, but it takes
a fair amount of time to do so. From a time efficiency
point of view, it would be better to unplug after
the constant current phase has finished, as it cuts
the charging time in half.

To achieve the constant current or constant voltage
behavior, means some analog thing must be switched
to the new mode. If a charging chip is used, the controls
for that are all inside the chip. All that's needed then,
is a means to "configure" what the chip is doing, like
set the level of constant current (varies with size of
batteries perhaps), as well as adjust the
constant voltage (varies with battery chemistry).
And whatever mechanism is used, it has to work if
the CPU is not running. As a charging chip should be
able to work without help (for things like stand-alone
charger station applications). While good chargers have
a processor to run a status display, it might not be
needed to actually get a charging chip to work. Those
could be programmed with strap resistors, current sense
shunts, that sort of thing.

Paul

 

[VanguardLH]

VanguardLH has written on 12/28/2013 10:57 PM:


Not an issue. He has tried this with several batteries.

I'll assume that means some of those batteries were new batteries, not a
bunch of old batteries sitting for years in a drawer or pulled from
other laptops. If he has a bunch of batteries for testing, where did
they come from? Did these other batteries come from other laptops? If
so, are these batteries fully charging in those other laptops so when he
uses them in the problematic laptop that he is testing with a fully
charged battery? When he puts a fully charged battery in the
problematic laptop (and WITHOUT the A/C charger connected so the laptop
only has the battery as a power source), does that laptop show the
battery at full charge or something much less?

So, and something else not mentioned, does he really use the portability
of the laptop? I've seen many users that get laptops for their small
size with integrated features that use them only as desktops (i.e., they
don't get toted around and are used in a fixed location). If so, and if
the laptop powers up even with a weak or dead battery, there's no point
in replacing it if it sits permanantly in one location with the A/C
adapter always connected to it. I've got an old Compaq (now Dell)
laptop that is rather big and heavy and use it as a backup to my desktop
PC since I have smaller and much lighter notebooks to tote around.

Since your friend had tried different batteries, has he also tried
different A/C chargers? If he has only one charger to use with that
laptop, has he checked the voltage out from that charger? That's only
an indicator of trouble since voltage may drop severely under load.

When the charger is connected to the laptop and supplying power, is the
laptop working? That is, with a dead battery, will the laptop still
function with the charger? If so, is that with the CPU at idle or
working at 100% for a long time (e.g., burnin-test)? Is that with all
USB ports used and the USB devices powered up and functioning? Are any
of the USB devices a high-power device, like a headset? In short, is
the laptop fully functional while running on the charger even with a
dead battery? At full CPU load for awhile, how hot is the charger?

 

[Juan Wei]

VanguardLH has written on 12/29/2013 3:59 PM:

I'll assume that means some of those batteries were new batteries, not a
bunch of old batteries sitting for years in a drawer or pulled from
other laptops. If he has a bunch of batteries for testing, where did
they come from? Did these other batteries come from other laptops? If
so, are these batteries fully charging in those other laptops so when he
uses them in the problematic laptop that he is testing with a fully
charged battery? When he puts a fully charged battery in the
problematic laptop (and WITHOUT the A/C charger connected so the laptop
only has the battery as a power source), does that laptop show the
battery at full charge or something much less?

So, and something else not mentioned, does he really use the portability
of the laptop? I've seen many users that get laptops for their small
size with integrated features that use them only as desktops (i.e., they
don't get toted around and are used in a fixed location). If so, and if
the laptop powers up even with a weak or dead battery, there's no point
in replacing it if it sits permanantly in one location with the A/C
adapter always connected to it. I've got an old Compaq (now Dell)
laptop that is rather big and heavy and use it as a backup to my desktop
PC since I have smaller and much lighter notebooks to tote around.

Since your friend had tried different batteries, has he also tried
different A/C chargers? If he has only one charger to use with that
laptop, has he checked the voltage out from that charger? That's only
an indicator of trouble since voltage may drop severely under load.

When the charger is connected to the laptop and supplying power, is the
laptop working? That is, with a dead battery, will the laptop still
function with the charger? If so, is that with the CPU at idle or
working at 100% for a long time (e.g., burnin-test)? Is that with all
USB ports used and the USB devices powered up and functioning? Are any
of the USB devices a high-power device, like a headset? In short, is
the laptop fully functional while running on the charger even with a
dead battery? At full CPU load for awhile, how hot is the charger?

What do you think that "A friend has a Dell laptop that runs well except
for one thing" means?

Yes. Yes. Working at 100% of what--CPU? Yes. No. Yes. No idea.

 

[VanguardLH]

VanguardLH has written on 12/29/2013 3:59 PM:

What do you think that "A friend has a Dell laptop that runs well except
for one thing" means?

Yes. Yes. Working at 100% of what--CPU? Yes. No. Yes. No idea.

Guess you should have your "friend" post here to ask for himself.

 

[Juan Wei]

VanguardLH has written on 12/29/2013 7:54 PM:

Guess you should have your "friend" post here to ask for himself.

Why? I answered all your questions.

 

[miso]

The chargers are generally "chemistry independent", i.e. you send them
commands for voltage/current. The deal is where do these commands come
from. In some cases, the battery can use SMB to request what it needs.
In other cases, they use a uP in the device to run the show. Or a
combination of both. It has to be independent of the operating system.
I've even seen the keyboard controller used for this function. You
should be able to charge the battery with no OS installed.

You have to bury the charging control deep enough that some hacker can't
blow up your battery. This is an issue with lithium ion. [Telsa got some
crap for their lithium ion fire, but they at least sensed the problem,
shut the car down, and told the occupant to get out of Dodge. They
actually got it right.]

Note the one manufacturer that had plenty of problems with battery
charging related fires is that fruity company in Cupertino, back in the
day when there would only be one OS on their hardware, they thought they
could control the charging from the OS. Big mistake.

One of the early versions of windows phone would brick if you drained
the battery all the way, and the charger couldn't save your bacon.
Engineers really need to think about these things, especially with
captive battery products (non-removable).

Things are always more complicated than you think when implemented
correctly.

 

[Paul]

miso wrote:

One of the early versions of windows phone would brick if you drained
the battery all the way, and the charger couldn't save your bacon.
Engineers really need to think about these things, especially with
captive battery products (non-removable).

Things are always more complicated than you think when implemented
correctly.

That's done for safety.

http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries

"Do not recharge lithium-ion if a cell has stayed at or below 1.5V
for more than a week. Copper shunts may have formed inside the cells
that can lead to a partial or total electrical short. If recharged,
the cells might become unstable, causing excessive heat or showing
other anomalies. Li-ion packs that have been under stress are more
sensitive to mechanical abuse, such as vibration, dropping and
exposure to heat."

It might not even be the phone OS preventing charging. It could
even be the charging chip which senses the voltage is too low,
and prevents charge initiation.

Even if an electronic device "cuts off" the load to protect
the battery from over-discharge, if left long enough, eventually
the battery will discharge to a too-low level. It's up to the user
to recharge yearly. Which reminds me, I have two batteries to maintain
It's been a year since the last charge, for both of them.

Paul

 

[VanguardLH]

VanguardLH has written on 12/29/2013 7:54 PM:

Why?

"A friend has a Dell laptop that runs well except for one thing" means?
Despite the attempt to use a smiley to disarm the reply, it looked like
you might be getting testy. Your friend has a vested interest in
solving the problem whereas you're just trying to help.

I answered all your questions.

You thought "Yes, yes, 100% of what (despite being told), No, Yes, No
Idea" really addressed each of those responses to a particular question?
That response seems very much flippant and deliberately not to address
the questions. Taking the questions in order and applying your answers
in the same order, we get:

"If he has a bunch of batteries for testing, where did they come from?"
Answer: Yes.
"Yes" doesn't say from where. Could be he bought new batteries (and has
yet to initially charge them properly).

"Did these other batteries come from other laptops?"
Answer: Yes.

"If so, are these batteries fully charging in those other laptops so
when he uses them in the problematic laptop that he is testing with a
fully charged battery?"
Answer: Working at 100% of what--CPU?
Haven't gotten to that question yet.

"When he puts a fully charged battery in the problematic laptop (and
WITHOUT the A/C charger connected so the laptop only has the battery as
a power source), does that laptop show the battery at full charge or
something much less?"
Answer: Yes.

"does he really use the portability of the laptop?"
Answer: No.
Then it is unimportant to spend money on new batteries, a new A/C power
brick, a new motherboard, or on anything. Use the laptop at its
stationary location with the power brick.

"has he also tried different A/C chargers?"
Answer: Yes.
Then Paul's proposal that the power brick included with the laptop is
not the problem since other chargers (which presumably work okay for
other laptops and provide the same output voltage and ampere load) don't
fix the problem with the Dell laptop in question.

"has he checked the voltage out from that charger?"
Answer: No idea.
Would help to know but only possible if your friend has a voltmeter or
multimeter. Low output voltage would mean the wrong charger is being
used or it's bad and need replacing. Good voltage means next is to test
its output voltage under load (i.e., with it connected to the laptop and
the laptop booted and running something, like Prime95, to get the CPU at
100% usage for awhile).

"When the charger is connected to the laptop and supplying power, is the
laptop working?"
Answer: Insinuated by your reply but out of order to the questions.

"will the laptop still function with the charger?"
Answer: Same insinutation applies here. Sorry for the duplicate query.

"If so, is that with the CPU at idle or working at 100% for a long time
(e.g., burnin-test)?"
No answer.

"Is that with all USB ports used and the USB devices powered up and
functioning?"
No answer.

"Are any of the USB devices a high-power device, like a headset?"
No answer.

"In short, is the laptop fully functional while running on the charger
even with a dead battery?"
No response. Not quite a duplicate query since the idea was to fully
load the laptop by using all USB ports that would then have additional
drain on the charger. If the laptop works just alone with the charger
then there still may not be enough reserve power from the charger to
recharge the battery. All its power is getting sucked up by the laptop
alone. By attaching devices to the USB ports, especially a high-power
USB device (which may require 2 USB ports to power it), the idea was to
suck more power from the charger than needed without all those extra
loads. If the charger cannot supply more power than just for the
laptop, there's nothing more it can provide to charge the battery.

"At full CPU load for awhile, how hot is the charger?"
No answer. Yes, the power bricks do get warm but they should not get
hot. It it feels overly hot then it is having to provide more amperes
than for what it is rated which also could mean it can barely power the
laptop but not the additional load of charging a battery.

Since your reply was flippant as it appeared intentional that it did not
address the questions, I figured you were getting peeved at having to
work on this and no responses seemingly to point a glaring finger at the
problem source. I figured your friend might more tolerate accidental
requeries of previously given information or provide more insight since
he has the laptop to test and experience with it.

 

[Juan Wei]

Juan Wei has written on 12/29/2013 8:14 PM:

VanguardLH has written on 12/29/2013 7:54 PM:

Why? I answered all your questions.

My apologies. The answers I provided were for the questions in the last
paragraph. I skipped the ones in the earlier 'graphs.

I'm afraid that installing a newsreader program and subscribing to this
newsgroup would be a little overwhelming for him.

But suppose you take what he told me at face value: the battery is not
seen by the computer (latest message) or the computer displays
"connected, not charging" (original message), and that the computer
works as long as the power adapter is plugged in.

Since I last posted, he has fiddled with the F2 and F3 function keys to
no avail, and has uninstalled the Microsoft ACPI Compliant Control
Method Battery from Device Manager, also to no avail.

Does this seem like a motherboard problem?

He's thinking about getting an external battery charger. What do you
think about that?

I do appreciate all of your efforts to help and educate. I can only wish
that he had brought his computer with him when he was here for dinner
yesterday.

 

[miso]

miso wrote:



That's done for safety.

http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries

"Do not recharge lithium-ion if a cell has stayed at or below 1.5V
for more than a week. Copper shunts may have formed inside the cells
that can lead to a partial or total electrical short. If recharged,
the cells might become unstable, causing excessive heat or showing
other anomalies. Li-ion packs that have been under stress are more
sensitive to mechanical abuse, such as vibration, dropping and
exposure to heat."

It might not even be the phone OS preventing charging. It could
even be the charging chip which senses the voltage is too low,
and prevents charge initiation.

Even if an electronic device "cuts off" the load to protect
the battery from over-discharge, if left long enough, eventually
the battery will discharge to a too-low level. It's up to the user
to recharge yearly. Which reminds me, I have two batteries to maintain
It's been a year since the last charge, for both of them.

Paul

Most charger chips have protection circuitry. The lawyers insist. ;-)
Actually a lot of chips have protection circuitry not even shown in the
datasheet, just to protect the chip from the clumsy guy with the scope
probe.

It used to be the case that you couldn't even buy a lithium ion battery
cell without the protector chip from the battery manufacturer. That is,
they were not put on the open market. Remember a notebook is like a
stick of dynamite. The Japanese kept tight controls on the cells for
safety, though it didn't hurt profit either. The Koreans on the other
hand just said screw it and sold the cells to anyone. That is why you
can now get lithium ion cells to rebuild old packs. Not so important in
computers, but really important in expensive instruments that you run
far longer than a computer.

I had a few Sony cells back in the day when you couldn't get them on the
open market. They were used in charger design then just set aside. I was
pretty shocked that they started to leak in a years time. The early
technology was pretty bad. On the other hand, I still have a Norelco
"James Bond" edition shaver with the same lithium polymer battery.

 

[VanguardLH]

Juan Wei has written on 12/29/2013 8:14 PM:

My apologies. The answers I provided were for the questions in the last
paragraph. I skipped the ones in the earlier 'graphs.

I'm afraid that installing a newsreader program and subscribing to this
newsgroup would be a little overwhelming for him.

But suppose you take what he told me at face value: the battery is not
seen by the computer (latest message) or the computer displays
"connected, not charging" (original message), and that the computer
works as long as the power adapter is plugged in.

Since I last posted, he has fiddled with the F2 and F3 function keys to
no avail, and has uninstalled the Microsoft ACPI Compliant Control
Method Battery from Device Manager, also to no avail.

Does this seem like a motherboard problem?

He's thinking about getting an external battery charger. What do you
think about that?

I do appreciate all of your efforts to help and educate. I can only wish
that he had brought his computer with him when he was here for dinner
yesterday.

He has used batteries from other computers. Supposedly those other
computers have no problem charging up their batteries. That means a
battery fully charged in another laptop still appears as "connected, not
charging" in the problematic laptop. A fully charged battery wouldn't
need immediate charging. But then "not charging" might be interpreted
as meaning, yep, battery at full charge so it doesn't need charging. He
would have to drain a test battery in the another laptop to something
less than full charge, like 30% showing on the power meter, and then try
the drained battery in the problematic laptop. I mention this only
because "not charging" could mean "cannot charge" or "doesn't need a
charge" (the test batteries from other laptops are already fully
charged). Semantics is often vague in computerese. Not charging
doesn't necessarily mean cannot or will not charge at all on a less than
fully charged battery.

My laptop is currently being borrowed by a family member and at another
house. It's an old Compaq and I did have to buy a new battery after the
original one wouldn't take a charge anymore (too old at about 5 years).
I really don't remember seeing any text status messages, just seeing the
power meter go down as the battery got drained until the laptop shutdown
when the battery got somewhere below 5% capacity. Since it's a lithium
battery, I usually never ran it down that low. I usually kept it topped
on charge since lithiums don't have the memory of nicads.

What does the power meter show for charge level of the battery in the
problematic laptop? Does it go down as the battery gets drained as the
laptop is left on while NOT using the A/C power adapter?

Does "no longer will charge the battery" mean the battery actually
starts at 100% when charged (in another laptop since he's using
batteries from there to test here) and then drops in charge over time as
that laptop gets used (and no A/C power source)? Somehow he has been
getting the battery charged for the problematic laptop. The other test
batteries had to come from somewhere so instead of buying an external
charger he could just use those other laptops to charge the battery.

 

[Juan Wei]

VanguardLH has written on 12/30/2013 5:17 PM:

He has used batteries from other computers.

Today, he told me that he bought a new battery when he thought the
battery was at fault.

That means a
battery fully charged in another laptop still appears as "connected, not
charging" in the problematic laptop. A fully charged battery wouldn't
need immediate charging. But then "not charging" might be interpreted
as meaning, yep, battery at full charge so it doesn't need charging.

I think that the message for a fully-charged battery is "Fully charged"
or "100%", rather than "not charging".

I mention this only
because "not charging" could mean "cannot charge" or "doesn't need a
charge" (the test batteries from other laptops are already fully
charged). Semantics is often vague in computerese. Not charging
doesn't necessarily mean cannot or will not charge at all on a less than
fully charged battery.

See above.

Does "no longer will charge the battery" mean the battery actually
starts at 100% when charged (in another laptop since he's using
batteries from there to test here) and then drops in charge over time as
that laptop gets used (and no A/C power source)?

It means that once upon a time, the computer was able to charge the
battery, and now it cannot.

Somehow he has been
getting the battery charged for the problematic laptop. The other test
batteries had to come from somewhere so instead of buying an external
charger he could just use those other laptops to charge the battery.

As I said above, he told me he had purchased a new battery.