new 9-cell battery questions and comments

[msafi]

i just received my new 9-cell battery and i would like to comment & ask some questions.

in addition to my new 9-cell, i have my older (4-cell?) battery which can give me about an hour of work. i'm planning to keep my 9-cell on my desk and only use it when i'm out of the house. at home i'll keep my 4-cell in. this way i don't have to worry about removing the battery when i'm planning to use the computer for extended periods (battery care procedure), because i really don't care how worse my 4-cell can get.

i have a question, however, is it safe to swap the batteries while the computer is in hibernation? (i seldom completely shut-down the computer)

as far as extending battery life goes, what is everyone doing?

i figured that setting the CPU on slow, screen brightness on level 4, and turning off the wifi can give me 7:40hrs. is there something else i can do to get more life?

from what i heard li-ion batteries don't really require much care (like conditioning, memory affect, etc). is that true?

and is the li-ion battery life measured by the number of charge/discharge cycles? if so, does that mean if i run my battery to the last drop before i re-charge it, i can get more actual life out of it?

sorry about all the text and questions, i hope some of it made sense!!

thanks,

[Jmmmmm]

i just received my new 9-cell battery and i would like to comment & ask some questions.

in addition to my new 9-cell, i have my older (4-cell?) battery which can give me about an hour of work. i'm planning to keep my 9-cell on my desk and only use it when i'm out of the house. at home i'll keep my 4-cell in. this way i don't have to worry about removing the battery when i'm planning to use the computer for extended periods (battery care procedure), because i really don't care how worse my 4-cell can get.

1. i have a question, however, is it safe to swap the batteries while the computer is in hibernation? (i seldom completely shut-down the computer)

2. as far as extending battery life goes, what is everyone doing?

3. i figured that setting the CPU on slow, screen brightness on level 4, and turning off the wifi can give me 7:40hrs. is there something else i can do to get more life?

4. from what i heard li-ion batteries don't really require much care (like conditioning, memory affect, etc). is that true?

5. and is the li-ion battery life measured by the number of charge/discharge cycles? 6. if so, does that mean if i run my battery to the last drop before i re-charge it, i can get more actual life out of it?

sorry about all the text and questions, i hope some of it made sense!!

thanks,

I numbered your questions, hope you don't mind.
My regular battery is 6 cells, btw.

1. it's fine. in hibernation, the computer is off

2. i just do about what you said. screen all the way down, processor on lowest setting, no wireless or optical drive use (is possible), close the screen when I can, close all unneeded programs, etc

3. You can try undervolting the processor. There are a few threads on here about it. I tried it and my computer freaked out, but maybe you'd have better luck.

4 pretty much. minimal care. going all the way down to 0% is actually a little bad for it (i don't remember why exactly - refer to answer #5), and if you stay above 80% it is optimal. However, once a month or so, if you don't ever discharge it, use it down to about 0%. But it seems like you will use the battery, so that isn't necessary. For extended periods or unuse, store the battery at ~60% in the fridge (not freezer).

5. battery life is measured in discharge cycles, but not quite as straightforward. The battery is used (and charged) in blocks, so that's why i said 80% above, because that's the edge of one. I think that if you just use one block, only that one will be depleted with the use. I think all lithium ion batteries last 300 or 500 (i don't remember which) cycles. However, the whole battery will lose life over time, regardless of use.

6. no. it's better not to, actually.

That's just going from memory about what I've read over time. I'm sure if you search on google you can find some good battery care websites. This battery isn't any different than any other lithium ion battery, as far as i am aware.

[pipspeak]

I was just learning all about batteries today

Basically the best way to store an unused Li-ion battery is said to be at 40-60% charge in a cool place (doesn't have to be the fridge, just anywhere under about 20C will do). Avoid really high heat at all costs.

Li-ion batteries also supposedly don't like being run completely flat, though you'll have to do that once in a while to "reset" the battery meter on the computer. They have absolutely no memory effect, so no worries there.

[Greg Gebhardt]

It is BAD, BAD BAD to run a L-Ion battery down to empty!

[mdarnton]

IBM does recommend running the battery down completely once in a while (circuitry in the the battery itself prevents a dangerous discharge level from being reached, at least that's what's been said here before). I believe this is for the calibration of the battery level meter, not for the health of the battery. If you think about it, it doesn't matter whether the battery's dead or if the computer shuts itself off because it *thinks* the battery's dead--same effect.

There was a thread here last week that contradicted the proposition that the battery counts discharge cycles, and said that calendar age is the issue.

I'm about as heedless of all this stuff as anyone could be--I don't pay any attention to anything--plug and unplug my T41 repeatedly throughout the day, keeping it plugged in and on most of the time (all night, too), and running on battery when I feel like moving around (maybe six or more times a day for a total of two hours or more), and my last battery lasted 14 months, so I do think this whole issue of babying the battery is a false one, and the expiration date concept is probably the correct concept.

The battery is their for my convenience--what good is it if I can't use the computer the way I want? If I lose a month or so on it by the way I use it, that scales out to $15 or $20 more a year--hardly a big deal.....

[GomJabbar]

If you think about it, it doesn't matter whether the battery's dead or if the computer shuts itself off because it *thinks* the battery's dead--same effect.

I don't think that the computer shuts itself off after a certain time based on the battery meter. I believe it shuts itself off when the battery voltage reaches a certain level. The purpose of recalibrating the battery is so the battery meter more accurately displays the time remaining while on battery power. In other words, so the meter doesn't go from say 100% to 30% in 2 hours then from 30% to 0% in 2 minutes.

If you have any written reliable information to the contrary, I'll be happy to read it.

[mdarnton]

Just experience with how my computer shuts off--I could certainly be wrong. As I read it, the battery system in my T41 is programmed to take certain actions at certain percentages, not voltages, and the percentages are projections based on history, not voltage.

As we've seen here numerous times over the past couple of years, "written" data is extremely contradictory on battery issues--take a point of view, and you'll be able to find a battery information site or manufacturer's recommendation that strongly says the opposite. That's why I've settled on a "who cares" approach to this problem--you can find an "expert" to absolutely back up anything you want to say about batteries, and people here do, claiming absolute veracity every time. Do a search here on terms like battery life and you'll find more than enough contradictory claims presented as The Only Truth to keep you spinning in circles for a long, long time.

[GomJabbar]

Just experience with how my computer shuts off--I could certainly be wrong. As I read it, the battery system in my T41 is programmed to take certain actions at certain percentages, not voltages.

I won't argue that. It's just as in my previous hypothetical example where the percent left goes from 30% to 0% in 2 minutes, the battery monitoring software changes it's percentage left very rapidly in the last 2 minutes. As it sees the voltage dropping, it changes % left accordingly. It is a fact that Lithium Ion batteries have very flat voltage curve from full charge to nearly dead. This makes it very hard to monitor battery life left by voltage only. But as the software sees the voltage drop at the end of the battery life, it adjusts itself accordingly. It just can't use battery voltage as a reliable guide during most of the discharge cycle.

I believe the converse is true. If the battery software has dropped the time remaining to a low percentage, say 10% (just a guess), yet the voltage is OK, it won't keep dropping the percentage until the voltage begins falling off. In other words, it adjusts itself on the fly as best it's able. Once the battery has reached a minimum acceptable voltage (ie. 3% = 10 volts {just a figure pulled out of the air}) it shuts down. The next time the battery is recharged, the software remembers how long it took to discarge the battery the last time so that it gives a more accurate indication of battery life left, the next go around.