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This battery situation makes no sense

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  • This battery situation makes no sense

    I had to restore my wife's laptop today (Compaq Presario 2104US - AMD - similar to HP ZE5000 series).

    She had two batteries, one in better shape than the other, but at least serviceable. Before the HDD crashed she could get at least an hour out of the better battery (this thing is a hog), more if not being hit heavily.

    When I installed the new hard drive (ostensibly more power friendly, but it's not a factor here), the battery life dropped to 7 minutes on the better battery.

    When I installed BatteryMon 2.1, the capacity of each battery reads as a design life of 3977 mAh (battery spec is 4400), but Full Charge Capacity for each battery is only 384 mAh (kind of coincidental, huh?). That's just a couple of AA batteries.

    How can the battery capability drop by 90% after the laptop comes back from a week's siesta to get a new HDD??? (by the way, I put the HDD in myself, so some shop didn't do something weird to me that I can tell).

    Also - even though one battery is clearly better than the other, both read 384 mAh. Obviously they are not reporting reliably, but one motivation for getting BatteryMon was to see if I could get the "real story" on what was going on here. I assumed the calibration was some how off in Windows, but in the past my experience was just that the battery would just run normally and Windows would just be innacurate.

    In this case, the laptop battery reserve drops so fast it crosses the threshold for shut down too fast for the laptop to warn me to plug it in.

    I can't believe these batteries suddenly went so drastically bad. Any ideas out there?

  • #2
    It is the smart battery and the charging circuit electronics in the PC that determine how much to charge a battery. Windows doesn't have much to do with it.

    My guess is that the batteries are not being full charged (which is a rather obvious conclusion I know). At some point the charging circuit decides the battery has been given as much charge as it can take and stops charging.

    You'll need to dug deeper to find the real cause. Find the model number of the main chip in the charging circuit and download the specs for it. Maybe the trigger for full charge is temperature increase and the new hard drive is hotter than the old one (just an example, and probably not the real cause).


    • #3
      Wrote an e-mail to dynapack

      Thanks for the comments. I doubt I'll see anything, but I asked Dynapack for a more detailed spec of their battery, and provided them with the metrics and log info.

      Still - isn't it coincidental that the pre HDD system (which always ran hot) lasted 10x longer than the new system?

      The changes were:
      Clean out the dust
      Free a blocked fan (clogged with carpet fibres, dust, etc.)
      New, more "fuel efficient" cooler running HDD
      Re-install OEM Windows disk

      Now - zero battery performance. I don't get it. So, you don't think there could be anything about the Windows config that could cause this? I have not touched the power settings - those must be at Microsoft defaults.

      Could there be any driver or other possible config changes that might affect these batteries?

      If I get a reply from Dynapack, I'll post it here.