[SOLVED] Brand new laptop, battery charges to 95% max (?)

Question

I've seen this widely on a simple google search for "last full capacity",
the laptop has been used for just two days, but acpi reports:
koko@TravelMate ~ $ acpi -biatc
Battery 0: Charging, 100%, until charged
Battery 0: design capacity 4400 mAh, last full capacity 4182 mAh = 95%
Adapter 0: on-line
Cooling 0: x86_pkg_temp no state information available
Cooling 1: intel_powerclamp no state information available
Cooling 2: Processor 0 of 10
Cooling 3: Processor 0 of 10
Cooling 4: Processor 0 of 10
Cooling 5: Processor 0 of 10
it won't go higher than that.
Is that normal? maybe some sort of overcharge protection?
my previous netbook always charged to 100% or even a bit more than the design capacity...
Last edited by kokoko3k (2014-05-10 13:31:54)

Answer 1

emeres wrote:Depending on the technology used, one (or several) of the cells might be shorted or almost shorted. Another reason might be wrong measurement [circuit] from either battery or laptop side. And the simplest reason would be that the laptop/battery was produced some time ago, depending on type of technology used, certain batteries lose significant amount of capacity over time (even if unused). Since it is brand new, get in touch with your supplier and get at least the battery exchanged.
If you try to discharge it first, do fully discharge it using LEDs or some other low current load until voltage drops to approximately 10% of nominal voltage, and then recharge it not extending 110% of time it needed to be fully charged Repeating this cycle might and does help with certain types of batteries. If I were you, I would not bother however and go get a replacement from the shop, unless it is really troublesome.
As for overcharge protection, there are usually thermal (usually the most important one), shortcircuit and overcharge (meaning overvoltage protection) protections built into the battery (usually one ic) and/or laptop.
None of that is applicable for Lithium Polymer or Lithium Ion batteries.  They should never drop below 3 volts.  Discharging them below that point will destroy them and risk a fire.  Charging Lithium based batteries is also non trivial and requires tight monitoring of voltage and controls on current and time.  Do not mess with LiPoly or LiIon, they truly represent a serious safety hazard if they are mistreated.   I note that your suggestions and descriptions of shorted cells are applicable to some non Li technologies; notably Nickle based batteries (Nickle Cadmium, Nickle Metal Hydride, etc...)  In general, those are not found in modern laptops because of their toxicity and relatively low energy density as compared to LiPoly.
http://www.empirerc.com/liposafety.htm
http://www.rcpro.org/net/ThreadView.aspx?threadid=260
http://magazine.sfpe.org/content/lithiu … ry-hazards
http://www.datasheetdir.com/BQ29400+download
http://batteryuniversity.com/learn/arti … _batteries
http://www.batteryuniversity.com/learn/ … ith_li_ion
Last edited by ewaller (2014-05-09 03:00:19)