On Tuesday, November 28, 2017 at 3:54:51 PM UTC-6, Paul wrote:
Andy wrote:
I bought a battery for my HP G60 laptop.

It must be a poor quality battery cuz it only lasts an hour at most.

If I buy a battery, is there a way I can be sure that it holds a full charge ?

Thanks,
Andy

I can give you a basic inventory on what is in
a battery system. I don't know all the details well
enough, to provide the exact right diagnosis.

*******

The battery consists of:

1) Multiple LiCo cells, with welded conductors between
cells. The cells have protection features, like each
cell has an internal fuse, to prevent accidents.
If a battery pack goes "open circuit", a protection
feature may have tripped to prevent a fire. It can never
work after that.

2) The battery has a PCB with a small "fuel gauge" chip
on it. This communicates over a serial bus, to the laptop.
The "fuel gauge" chips, there are many brands, and the
right chip must be in there for the laptop to work with it.
The fuel gauge keeps track of "charge cycle count", as
well as a "capacity loss parameter", so that the laptop
can figure out the reduction in capacity with time, and
be in a better condition to detect when it's time to
hibernate the computer (before the battery drops below
0%). If the battery loses 0.1% of its life on each full
recharge, and the gauge logs 100 charge cycles, then the
battery has lost about 10% of absolute capacity. The fuel
gauge includes a number of registers, with information like
that stored inside. It must be properly programmed at the
factory, to represent the behavior of the cells well.

3) The plastic casing on the battery has eight contacts.
Two for VCC. Two for GND. At least one contact of the
remainder is used for the serial bus. Some packs also
have an ENABLE pin, and that prevents energy from appearing
on VCC and GND, unless the battery pack is seated in the bay.
So if you drop your screwdriver across the power blades while
the pack sits on your desk... it might not catch fire :-)
The ENABLE pin inside the laptop, would ground the pin
and signal the pack is now inside a laptop, so it's safe
for VCC and GND to connect to the actual battery cells.

4) The laptop itself has an autonomous charge management
subsystem. Even if the CPU isn't running, some kind of
chip in there charges the battery, and stops charging
before the battery is overfilled in a dangerous way.
A battery may not be properly charged, due to a failure
in that subsystem, or a failure of the power adapter.

*******

It could be that the charging process is
stopping after the CC phase. That would leave
you with 65% fuel (second graph). Maybe it takes
less time than normal, to fill to 65%. And then
less time than normal, to empty it.

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

I can't say much more than that.

A battery bought from HP, probably works correctly.

Batteries should always be bought from "high volume"
sellers. A battery sitting on the shelf in a "mom and pop"
computer store, could already be ruined by aging. You
want "freshly constructed" laptop batteries for
best results. A ten year old battery, may not take
a lot of charge cycles due to age.

I suspect a disagreement between (2) and (4), and the
pack might not be properly designed for G60. The aftermarket
suppliers try their best, when making this stuff. They
probably weren't trying to save money, by cutting corners.

Savvy buyers, use the reviews from previous customers, to
get some idea whether the packs are "good". If the supplier
is a middle-man and not a manufacturer, then there can be
lot-to-lot variation. Like, if the middle-man buys
from Larry one day ("good" pack) and from Moe the next
day ("bad" pack), then even sellers with reviews may
not be enough.

If the batteries were nickel cadmium, like many years ago,
there wouldn't be all these features. Batteries are
this complicated, because of the risk of fire with this
particular battery chemistry.

Paul

Thanks to all for the good info.

I will stick to buying only HP batteries and not use the battery at all if I am using the charger.

Andy