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Powerbook G4 battery capacity

Discussion in 'PowerPC Macs' started by Petoz, May 22, 2008.

  1. macrumors 6502


    I recently bought a 12" Powerbook G4 from ebay, and am curious to know about the battery capacity. It came with the original Apple battery, and it usually powers off before the battery is at a low percentage power. So I have installed Coconut Battery and Battery Health Monitor to check how the battery is doing.

    Both say that the battery capacity is now 6393mAh, and the original capacity was 4200mAh. As such, they say the battery health is 100%. How is this possible? How can battery capacity increase? i presume this is wrong. Is there any way to correct this? The powerbook, according to the apps, is 65 months old (it is an original 867MHz model). Both battery apps also say the battery has gone through 59 charge cycles.

    Any suggestions/thoughts? Thanks.
  2. macrumors regular


    The only guess I can offer is that the battery software is guessing at the mAh value based on the voltage the battery is producing. That is how it works. The capacity (mAh) is correlated with voltage. If the voltage is higher than expected, the mAh value will appear to be more.

    Why is this happening ? Perhaps the battery is from a newer machine or is a replacement that is rated for a higher load. That would explain it.

    59 cycles seems small for a machine that is over 5 years old. This is evidence that the battery is not the original. -- Also - there was a battery recall for these machines.

    The good news is that it does not seem to be a problem. I would not be at all concerned if I were you. I owned one of these machines since 2004 and sold it on ebay last year. It was 1.25 ghz with 1.25 gig of RAM. I had replaced the hard drive with a 160 gig seagate. I was very happy with the machine but I replaced it with a MBP to get into the Intel game.
  3. macrumors 6502


    Thanks for the info. I thought 59 cycles seemed quite low too. I was under the impression it was the original battery. Did the battery recall replace them with higher voltage batteries? Or greater capacity?

    As for it not being a problem. I am not too worried about the battery itself. But the powerbook turns off when the battery shows about 40%, but this changes. And I have not used it enough to figure out if this happens every time, and at what percentage it turns off. I believe it does this because of the misread capacity. So I agree, the problem isn't drastic, but it would help if I knew accurately how much battery is actually left. Is there any way of sorting it out? Or would I have to get a new battery for that?

    Thanks again for the response.
  4. macrumors 6502


    Also, I have just realised (as It is charging next to me now) that when charging, the percentage charged jumps from about 45% to 100% instantly. It increases gradually, as it should, until the mid-40's%, but then suddenly becomes 100%.

    I don't know if this will help highlight the problem, or help explain the issue. I just thought it might be relevant.
  5. macrumors newbie

    have you calibrated the battery?
    (look up on the apple website for calibration methods).

    if that doesn't work, try to reset the PMU (again, look it up on the web)

    Finally, maybe different models of battery can fit into the PB12", so just check that it's 1) an Apple battery, and 2) a battery made for the PB12" (you should be able to find this on the Apple support website).
  6. macrumors newbie


    Sorry for digging up old thread because I don't want to make a new one.

    I'm new in Macintosh product. I just bought Powerbook G4 12", can I use the battery while it has only 321 mAh available (around 8 minutes left if I dont plug the AC adapter). Will it affect the logic board if I use that battery?. I'm afraid it will :(

    Here's the information:

    System Power Settings:

    AC Power:
    System Sleep Timer (Minutes): 10
    Disk Sleep Timer (Minutes): 10
    Display Sleep Timer (Minutes): 5
    Dynamic Power Step: No
    Reduce Processor Speed: No
    Automatic Restart On Power Loss: No
    Wake On AC Change: No
    Wake On Clamshell Open: Yes
    Wake On LAN: Yes
    Wake On Modem Ring: Yes
    Display Sleep Uses Dim: Yes
    Battery Power:
    System Sleep Timer (Minutes): 10
    Disk Sleep Timer (Minutes): 10
    Display Sleep Timer (Minutes): 5
    Dynamic Power Step: Yes
    Reduce Processor Speed: No
    Automatic Restart On Power Loss: No
    Wake On AC Change: No
    Wake On Clamshell Open: Yes
    Wake On Modem Ring: No
    Display Sleep Uses Dim: Yes
    Reduce Brightness: Yes

    Battery Information:

    Battery Installed: Yes
    First low level warning: No
    Full Charge Capacity (mAh): 324
    Remaining Capacity (mAh): 321
    Amperage (mA): 0
    Voltage (mV): 12279
    Cycle Count: 280

    AC Charger Information:

    AC Charger (Watts): 50
    Connected: Yes
    Charging: No

    Hardware Configuration:

    Clamshell Closed: No
    UPS Installed: No

    I will appreciate if someone can help me. Thanks a lot.
  7. macrumors 65816


    Always start a new thread. For one, most people won't see your problem, and second, many people get upset when someone hijacks another thread with their own issues.

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