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Battery cycles?

Message #1 - Posted 2006/04/21 - dumbstruck

Does usage of a battery reduce it's life? I want a PB17 battery to last several years, so should I limit to only a certain number of drain downs per week or month?

This model gets alarmingly hot while being used or charged. I very rarely actually need to unplug the AC source, but do it as a slight convenience. Above all, I never want to have to buy a new battery for a rare needed use in the far future.

And bonus esoteric question... there seems to be an internal fan and does anyone know if I overwork it by turning the unit on it's side? In particular, would a 90 degree clockwise rotation make the fan work against the new path where heat is trying to rise (from the original right to left side of keyboard)?

Message #2 - Posted 2006/04/21 - Chris McDonald

"dumbstruck" <dumbstruc@gmail.com> writes:

Does usage of a battery reduce it's life? I want a PB17 battery to last several years, so should I limit to only a certain number of drain downs per week or month?

Some info here: http://www.apple.com/batteries/

Chris.

Message #3 - Posted 2006/04/21 - Garner Miller

Previously, dumbstruck wrote:

Does usage of a battery reduce it's life? I want a PB17 battery to last several years, so should I limit to only a certain number of drain downs per week or month?

Yes, you should. As I'm sure you remember, NiCad batteries *required* deep discharges, or they'd lose capacity. Lithium batteries, such as those found in your PowerBook, are just the opposite: They lose a little bit of charge capacity every time they're discharged and recharged. Further, the deeper the discharge, the more wear is done on the battery -- so partial discharges will impact the battery's capacity less than full (until it goes to sleep) discharges.

This isn't to say you shouldn't ever use it on battery power, of course! But if power is available and convenient, it's best to hook into it to prolong the life of the (rather expensive) battery. You're on the right track.

The numbers I usually see for lithium batteries are 200 to 500 complete discharge/charge cycles before the battery starts showing significant loss of capacity. So if you discharged it fully every day, and recharged it, it'd last a year or so. Half-discharging it every day, you'd get two years. And so on.

Other factors will affect it, including simple age, but you should get several years out of it if you treat it as I outlined above. We have an iBook G4 12" that's about two and a half years old. Most days, it lives plugged into its power adapter; it only ends up running on batteries a few days a month. When new, we'd get about 3:15 out of the battery; now we can get a bit over 3 hours. So it's still fairly strong.

And bonus esoteric question... there seems to be an internal fan and does anyone know if I overwork it by turning the unit on it's side?

I have no idea. And I just sat down with my coffee, so I'm not ready to theorize just yet. <grin>

I'll leave that one for someone else.

Hope that helps.

Garner R. Miller
Clifton Park, NY =USA=
http://www.garnermiller.com/

Message #4 - Posted 2006/04/22 - Marc Heusser

Previously, dumbstruck wrote:

Does usage of a battery reduce it's life? I want a PB17 battery to last several years, so should I limit to only a certain number of drain downs per week or month?

See http://www.apple.com/support/macbookpro/care/ (applies to 17" PB too as far as batteries are concerned).
You cannot avoid the simple aging of the battery - after 3 years a Li battery may fail regardless of how you used it.

HTH

Marc

Switzerland/Europe
<http://www.heusser.com> remove CHEERS and from MERCIAL to get valid e-mail

Message #5 - Posted 2006/05/01 - Stefan Aschenbach

On 2006-04-22 01:19:02 +0200, Marc Heusser said:

Previously, dumbstruck wrote:

Does usage of a battery reduce it's life? I want a PB17 battery to last several years, so should I limit to only a certain number of drain downs per week or month?

I've not checked the links posted earlier, but some more rules to extend battery life:

Of course less use means less loss.
Not only deep discharges reduce the lifetime, but also high charges. The last 10 to 20% of charge
are forced into your battery with the highest current, so they wear out the battery.
The power managment unit should take care of that, so you are not constantly loading it from 99% to 100%, and again after 10min. But it will do so if you are constantly switching from battery to power use.

It's generally a good idea to take out your (80% charged) battery if you only use your PB with the powerplug in. It will still slowly lose charge that way and age, but far less than normal.

I have a old Powerbook here which runs on its battery for 3 hours. Not bad for about 10 years of age.

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