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You are here: MacNN Forums > Hardware - Troubleshooting and Discussion > Mac Notebooks > If a powerbook gets too cold, will it go to sleep?

If a powerbook gets too cold, will it go to sleep?
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tweezer13
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Oct 14, 2005, 09:02 PM
 
I've been having problems recently with my PB going to sleep randomly (thread at bottom of page). I've noticed that when it's warmer in my room it doesn't do it as much, if at all. When it's cold (I keep my window open in my dorm room here in MPLS) it tends to do it a bunch. I realized it today when it was real cold when I woke up, I turned the PB on, and it feel asleep twice when I was using it. It warmed up to about 68 today, and it's been running perfectly. I don't have my manual here, so I'm not sure what the recommended room temp. is, if there is one. Any clue?

-Kurt
     
Dork.
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Oct 14, 2005, 09:20 PM
 
I don't think cold would really affect the laptop. If it did, I think you'd need to be running it in extreme cold(sub-freezing), and the screen would probably suffer ill effects before the battery.

But batteries are notoriously flaky, and it's possible that if you have marginal cells to begin with, they might be outputting less voltage in the cold. The power management turns the laptop to sleep if the battery runs down enough that it can't keep the voltage at the proper level. (in fact, most people's batteries fail when only one of the four or six cells in the battery die, even if the other cells have plenty of charge left, but that's enough to decrease the total voltage below the threshold.

Note I said voltage, not current. You'd think that only the current capacity would matter for batteries, but the power management system does monitor voltage also, and tries to avoid an undervoltage condition that might damage components. And flaky cells can output less than nominal voltage.

Try downloading an app like xBattery that monitors battery voltage and current, and see if anything dips when you're in the cold!
     
tweezer13  (op)
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Oct 14, 2005, 09:42 PM
 
Interesting, thanks for the info. That might be the case with the battery, when I felt my laptop in the morning, it was pretty darn cold. Right now, it's a comfortable temp in my room and it's running fine.
     
OogaBooga
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Oct 15, 2005, 10:13 AM
 
Batteries lose their power in cold weather.
     
Dork.
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Oct 15, 2005, 10:34 AM
 
Originally Posted by OogaBooga
Batteries lose their power in cold weather.
That's not strictly true. I'm not sure if what I'm about to say really applies to the Li-Ion batteries that laptops use, but that's never stopped me before!

All batteries create charge through a chemical reaction. Even when the battery has no load, there is still some (very) small reaction happening, so that eventually they will run out of charge all on their own. That reaction is somewhat temperature dependant, and is harder to make happen in colder weather. So, a cold battery in storage will actually last a little longer than a warm battery in storage (since the pace of the chemical reaction is slowed), but a cold battery with a load on it will not last as long (since there needs to be more of a reaction to create the same current.)

I'm supposing that if the battery is flaky to begin with, it might be having trouble maintaining a constant voltage even in warm weather, and putting it in cold weather will make the voltage of a particular cell go below the threshold....
     
Sakino
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Oct 15, 2005, 11:47 AM
 
I'm going to assume it will. Have you ever taken your ipod out on a cold winter day? My ipod was notorious for giving up when it got cold. The plastic and metal(aluminum I am assuming) only add to it dropping below the its desired temperature. Therefore I would say the powerbook would most likely do the same? Maybe below 40 degrees you will see performance drop off, although I really don’t know. I just never put my computer in that type of situation, if it were I would let it sit at room temperature for awhile.
     
   
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