Darac Marjal wrote:
> Perhaps so, but if the charge isn't increasing, then that's basically
> "full".
Probably so.
> Batteries usually note three main values in their "fuel gagues" (a small
> chip in the battery): current charge, current maximum charge and
> designed maximum charge. The "designed maximum charge" is written at
> manufacture time and the "current maximum charge" is updated every so
> often.
>
> The ratio between current charge and current maximum charge give your
> your percentage full. The ratio between current maximum charge and
> designed maximum charge gives an indication of battery health (that is,
> if the battery was designed to hold 100Wh but now can only hold 20Wh,
> it's basically dead).
Install 'acpitool' and then see what it says for your battery. Mine
says this at this time. The information available will vary from
vendor to vendor. Yours might have a different set of fields.
rwp@dismay:~$ acpitool --battery
Battery #1 : present
Remaining capacity : 65260 mWh, 100.0%
Design capacity : 71280 mWh
Last full capacity : 65260 mWh, 91.55% of design capacity
Capacity loss : 8.446%
Present rate : 0 mW
Charging state : Full
Battery type : Li-ion
Model number : 92P1137
Serial number : 772
You can also get this data from /proc and-or /sys but recent kernels
have changed the locations so now I find it easier to use acpitool to
dump this information.
The battery above is in good shape and the last full capacity is 91%
of the design capacity. But a worn out battery may report something
down to 20% of capicity or worse.
It is possible that the reporting on your battery is reporting the
percentage of design capacity rather than the current capability.
> Resetting the fuel gauge varies from battery to battery, but the typical
> way is to drain the battery (so, take the charger out and run the laptop
> until it shuts down. DON'T try to over-drain the battery by starting it
> at this point), then charge the battery to full again
I think it is a good idea to do this once a month. A battery used
well will last longer.
> (plug back in, but
> don't start the laptop - let the battery charge at full rate until it's
> at 100%. You'll need to estimate how long this usually takes). The idea
> is that the fuel gauge monitors the increase in charge and, when the
> increase tapers off, that's your maximum charge.
I think it is okay to plug it in and also start the laptop. I have
always monitored the charging this way. But for the reset it is
important to allow it to charge all of the way to full in one cycle.
> Don't try this too often, though. Deep discharges are also bad for
> Lithium Ion batteries. If in doubt, read the manual :)
"A ship in harbor is safe, but that is not what ships are built for."
The same is true for laptop batteries. I use mine and that means I
will cycle it. As long as I have gotten good use from something then
I don't feel bad if I have eventually worn it out.
Bob
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