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17" PowerBook G4 and battery life

Message #1 - Posted 2003/12/11 - Chey

Picked up a 17" PowerBook 1Ghz G4 from a CompUSA. Got $800 discount for a floor demo.

First thing I noticed was that battery life is much shorter, but I am not too surprised considering the large screen and I have battery saving modes turned off.

Any PowerBook users care to share their experience with me?

Thanks in advance.

Message #2 - Posted 2003/12/16 - Thomas Reed

Previously, Chey wrote:

Picked up a 17" PowerBook 1Ghz G4 from a CompUSA. Got $800 discount for a floor demo.

First thing I noticed was that battery life is much shorter, but I am not too surprised considering the large screen and I have battery saving modes turned off.

"Much shorter" meaning what? I've found the performance of my 17" G4 to be about comparable to my older Wallstreet. I've gotten as much as 4 hours out of it, by turning off AirPort and Bluetooth and doing just simple text editing in BBEdit and Eudora.

If you're not getting that much, your battery may need reconditioning. To do this, use the machine unplugged until it goes to sleep. (Ignore the dialog that appears warning you to put the machine to sleep -- make it do it itself.) Then plug in and charge to full capacity.

Some folks recommend a "trickle discharge" method, where you set things up so it will never go to sleep, then just leave it on, unplugged and doing nothing, until it goes to sleep due to low power. Then you recharge to full capacity, without using the machine during recharging. I don't know how necessary all this is, but it's something to try.

Message #3 - Posted 2003/12/16 - Peter Renzland

Thomas Reed wrote:

First thing I noticed was that battery life is much shorter, but I am not too surprised considering the large screen and I have battery saving modes turned off.

"Much shorter" meaning what? I've found the performance of my 17" G4 to be about comparable to my older Wallstreet. I've gotten as much as 4 hours out of it, by turning off AirPort and Bluetooth and doing just simple text editing in BBEdit and Eudora.

Don't forget to dim the display, as well.

If you are so inclined, you can estimate how long your battery charge will last at the current load: Measure your charge, measure your load, divide.

How to you measure your battery's charge and your current load?

ioreg -p IODeviceTree -n battery -w0 | grep Bat

Note the Capacity, the Charge ("Current"), and the Load ("Amperage").

If your Charge is 5000 mAh and your Load is 1000mAh, that means you get 5 hours. (Right now, my 500 MHz iBook, with its 2.5 year old battery that only has 3284 mAh of Capacity left (down from its original 4000 mAh), has a load (on battery -- ioreg won't tell you the discharge load while not discharging) of 692 mAh, which means I get 3284/692 = 4.74 or 4 hours and 45 minutes, approx. on a full charge.

With no power saving at all, I get a load of closer to 1000mAh, which yields more like 3:15 hours of usable battery time.

If running the above ioreg command is too much of a mystery, there is a very nice program, xBattery, which lets you monitor these things.

If you're not getting that much, your battery may need reconditioning. To do this, use the machine unplugged until it goes to sleep. (Ignore the dialog that appears warning you to put the machine to sleep -- make it do it itself.) Then plug in and charge to full capacity.

Some folks recommend a "trickle discharge" method, where you set things up so it will never go to sleep, then just leave it on, unplugged and doing nothing, until it goes to sleep due to low power. Then you recharge to full capacity, without using the machine during recharging. I don't know how necessary all this is, but it's something to try.

Calibration estimates the battery capacity.
Tricke-Discharge seems to rejuvenate an older battery. Probably not much use for a newish one.

-- Peter in Toronto

Message #4 - Posted 2003/12/16 - Lou Pecora

Previously, Peter Renzland wrote:

How to you measure your battery's charge and your current load?

ioreg -p IODeviceTree -n battery -w0 | grep Bat

Note the Capacity, the Charge ("Current"), and the Load ("Amperage").

If your Charge is 5000 mAh and your Load is 1000mAh, that means you get 5 hours. (Right now, my 500 MHz iBook, with its 2.5 year old battery that only has 3284 mAh of Capacity left (down from its original 4000 mAh), has a load (on battery -- ioreg won't tell you the discharge load while not discharging) of 692 mAh, which means I get 3284/692 = 4.74 or 4 hours and 45 minutes, approx. on a full charge.

This is good information, but I think you mean the load to be in mA, not mAh or the units will not be correct. Using your numbers (but my units):

Charge (Capacity) is 5000 mAh

Load (Amperage) is 1000 mA

we get 5000 mAh/1000 mA = 5 h.

-- Lou Pecora
My views are my own.

Message #5 - Posted 2003/12/17 - Chey

Well, this particular 17" PowerBook was a floor model I got for $2200 so I am guessing since it sat plugged in since it was opened by the store the batter probably needs reconditioning.

I have tried two times to run the battery down and do a full uninterrupted recharge, but I average less than 2 hours. It never occured to me to turn off Bluetooth and Airport which I am doing now and see if I can up the battery life a bit more. Although, I have not actually timed how long the battery last, but I am certain it isn't lasting past an hour and half by very much.

I can understand battery being short especially with a 17" screen and serious power underneath the hood on this baby.

Thanks for the advice to one and all for my post.

Thank you and Season's Greetings.

Message #6 - Posted 2003/12/17 - Peter Renzland

Lou Pecora wrote:

Peter Renzland wrote:

How to you measure your battery's charge and your current load?

ioreg -p IODeviceTree -n battery -w0 | grep Bat

Note the Capacity, the Charge ("Current"), and the Load ("Amperage").

If your Charge is 5000 mAh and your Load is 1000mAh, that means you get 5 hours. (Right now, my 500 MHz iBook, with its 2.5 year old battery that only has 3284 mAh of Capacity left (down from its original 4000 mAh), has a load (on battery -- ioreg won't tell you the discharge load while not discharging) of 692 mAh, which means I get 3284/692 = 4.74 or 4 hours and 45 minutes, approx. on a full charge.

This is good information, but I think you mean the load to be in mA, not mAh or the units will not be correct.

Right you are, of course. Sorry about typo.

BTW, last night I talked with a friend who owns a brand new 15" PBG4. Battery capacity = 4400 mAh
Load, typically, = 1800 mA

PM's estimated time -- 2:20h

CPU about 85% idle, plenty things plugged in, incl. external monitor and wireless kb & mouse, bluetooth & airport.

-- Peter

Good thing he has a 2nd battery, and he can hot-swap.

Message #7 - Posted 2003/12/17 - Lou Pecora

Previously, Peter Renzland wrote:

BTW, last night I talked with a friend who owns a brand new 15" PBG4. Battery capacity = 4400 mAh
Load, typically, = 1800 mA

PM's estimated time -- 2:20h

CPU about 85% idle, plenty things plugged in, incl. external monitor and wireless kb & mouse, bluetooth & airport.

-- Peter

Good thing he has a 2nd battery, and he can hot-swap.

I think the 2nd battery is a necessity. Which brings me to: where do people recommend going to buy one? I did some searching before getting my 15" Al (1.25 GHz) PB and bought a battery only to find it was the wrong size. So I must be missing something. Any clues? Thanks.

-- Lou Pecora
My views are my own.

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