Laptop battery no longer gets charged

Yousuf Khan wrote:
On 18/08/2011 1:59 PM, BillW50 wrote:
In ,
BillW50 wrote:

Yup, I have seen those too. And those of us, who fly a lot with our
laptops... also discovered that most of the time the aircraft only
supplies so much power per outlet and that is it. And laptops are
pretty good about adjusting for a lower wattage supply. And what they
generally do is to disable battery charging but the rest of the
laptop works fine otherwise.

That is another thing to check once you know the problem isn't the
battery. Remember I offered to send you a battery to check your
computer with. Anyway your AC power supply could also not put out all
of the amperage that it used too. In that case, the laptop will
refuse to charge the battery, but work fine otherwise.

Oh yeah Yousuf, not only could I send you a battery to test, but I also
have AC power supplies too that I could send for you for testing. You
could email me by changing KOM to COM if you are interested.

Well, I ended up ordering a new battery online, and it came in today. I
put it in, and it's being successfully charged up. So my problem is
solved. Just wondering what caused the previous battery to fail in the
way that it did?

Yousuf Khan

I understand with the laptop battery technology, it isn't safe to
charge the battery, if the terminal voltage drops too low. The charger
won't touch it in that case. Now, why it's showing a little capacity
left, I don't know. Perhaps the undervoltage cutoff threshold value
has shifted ?

http://batteryuniversity.com/learn/a..._ion_batteries

"Over-discharging Lithium-ion

If the discharge continues to about 2.70V/cell or lower, the battery’s
protection circuit puts the battery into a sleep mode. This renders the
pack unserviceable and a recharge with most chargers is not possible."

"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."

HTH,
Paul