45W or 65W and battery damage

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Level 1

2 points

45W or 65W and battery damage

I just realized that the possible reason my PBook 15" 1.67HRz battery was only lasting 1 hour and 'not really fully charging' was that the two powerchords I was given (sold) with this computer were only 45Watts. They did not have the large "45W" pring on the white brick, so it was hard to know.

I went out and bought a new 65W power chord from the Apple store tonight (M8943LL/A) and am currently charging the battery (after letting it run down to 1% when the computer shut off). Man, the brick gets real hot!!

I assume the previous user (a family member) was using 45W cables too. They said the orginal powerchord broke, and they were told these were fine (didn't understand the wattage difference).

The Battery Power readings in my System Profiler (10.4.4) report:

Full Charge Capacity (mAh): 3959
Remaining Capacity (mAh): 3443

Do these numbers reveal anything?
How long can I expect the battery to last?

Is it true that you can use a 65W on an ibook,Tbook, others that only require the 45W, but not the other way around?

Thanks
Jake

Pbook G4 15" 1,67 Ghz, Shiny Metal, iBook 14" 1GHz, Tbook 700MHz, Mac OS X (10.4.4)

Posted on Jan 13, 2006 9:45 PM

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Answer 1

Jrsy Man

Level 4

1,890 points

Jan 15, 2006 2:35 AM in response to bluecool

Hi Jake,

While I am not 100% certain, I don't believe the 45w AC power adapter has damaged your battery. Aside from the calibration you've already performed, you can also try downloading and running the Battery Update to see if that helps extend battery life. Secondly, you can also check out coconutbattery for more stats on your battery's status.

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Answer 2

JDee

Level 5

6,491 points

Jan 15, 2006 5:34 AM in response to bluecool

Hi bluecool --

Is it true that you can use a 65W on an ibook,Tbook, others that only require the 45W, but not the other way around?

I don't know about the first part of the above question, but here's an excerpt from an Apple Developer Note regarding the use of 45 W power adapters on machines (like yours and mine) that are designed to be used with 65 W power adapters:

Note: The 15-inch PowerBook G4 is designed to use the 65 W Apple Portable Power Adapter which ships with it (the adapter is labeled with a “65W” icon on the lower front). A 45 W Apple portable power adapter works with the 15-inch PowerBook G4, but may provide insufficient power during some activities and power may be drawn temporarily from the battery. Therefore a 45 W power adapter is not recommended.

-- JDee

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Answer 3

Jan 15, 2006 11:39 AM in response to JDee

Hi bluecool -

I think JDee pretty much answered your question. The 45W supply should not damage your battery but it may not have sufficient capacity to charge the battery when you are using the laptop at the same time that you are plugged in. However, you should be able to fully charge the battery if you don't use the computer (leave it off) while it is plugged in to the 45W supply (but you should monitor the power adapter to make it doesn't get too hot). It may be that your battery capacity has degraded over time and that is why you are not getting long life.

In general, you may use a supply that has a greater max wattage than your computer requires - this only means that the supply has more than enough power capacity to handle your device. The only time this can be troublesome is if some circuit in the device (computer) being powered develops a short or near short - then the higher wattage supply means that more amps (current) can flow into the circuit and this may result in greater damage during failure than might otherwise occur. But under normal operating conditions, more capacity is not a problem.

Using a smaller wattage supply than required is not recommended for long periods as this will put greater stress on the supply and reduce it's life span.

John

TiPB G4-500 Mac OS X (10.3.9)

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Answer 4

Ricktoronto

Level 6

11,560 points

Jan 15, 2006 8:41 PM in response to John Harkins

A 2 watt power supply will charge a battery just slowly. Think of a car battery which might be 90,000 mAhours vs. 4,000 in a Powerbook. A 2-5W trickle charger will charge it and maintain a charge while away for example. So 45W will just take longer and may now provide enough wattage to charge and run but using the lower power charger would give you more time than the battery alone.

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