I have a similar issue. I've had my laptop for about 4 or 5 months. Ever since I got it, the indicator tells me I have about 2 hours left at about 50%, and maybe 1:30 at 30%, but right when it hits 30%, it drops by 2-3% every minute or two and all of a sudden I have no battery left. In other words, when it says 50%, I really have maybe an hour left. The interesting thing is that from 100->50%, I generally get 2:30 hours or so. The scale does nto seem to work from 50% and down. Does anyone know what I can do to remedy this situation? I have bios A05.

Thanks.

The percentage/time remaining scale is only an approximation of the charge/time left in the battery.

It is not etched in stone and is often wrong. The software that monitors the battery state is based on the assumption that the battery itself is in good condition. It takes no reference to the age of the battery, it assumes it's in new condition and bases its findings on the same. These findings are originally determined under laboratory conditions with everything working fine. Some 'boffin' has declared that a new battery, fully charged and in good condition, can be expected to last APPROXIMATELY 'x' number of hours with the bare minimum of applications/services running on the computer and the CPU under low load.

So in theory with a new battery that is in good condition, the percentage remaining will be almost correct..I say ALMOST (approximation y'see) An older and well used or possibly ABUSED battery that is shown to have a certain percentage of charge/hours remaining, will in reality have only a fraction of the shown life left. 

100% charged when applied to a new battery will in reality be the amount of charge the cells can hold given the condition/age of them...an older well used battery showing 100% charged is actually telling you that the battery is holding as much charge as it can, which means that the available area that stores the charge is full. Considering this charge holding space decreases due to naturally forming crystaline structures in the electrolyte that grow larger due to recharging/age/use/abuse Add to this oxidation build up that affects the space between the positive and negative plates in the battery cell 100% charged can actually mean a whole lot less when compared to a new battery.

In simplified terms, take a beaker filled to the brim with water(this is a fully charged new battery for this demonstration) and a handfull of pebbles (these represent a recharge or crystal build up) drop one pebble at a time into the water the overflow represents the charge that can no longer be accommodated by the battery (the beaker). The more pebbles you drop in the less space there is for the charge but the beaker (battery) is still 100% full. Go figure

bluetracker: thanks for your response. However, I still don't really think that answers the question for two reasons: a) my battery is relatively new and this happened even when I first got the computer. b) From 100->50%, the indicator is accurate and ticks down slowly. From 50->20 and less it is no longer accurate and just drops off all of a sudden. It is not that it says 100%, 4:00 hours and I expect the full 4 hours. Rather, i'm more worried that it no longer gives me an accurate representation of time when I get further down in the charge cycle. I think there might be some software issues that should be looked at. Do you personally have this problem or does anyone aside from me and NYUArab have this?

So I'm supposed to read minds now huh?

Seriously tho' battery performance takes a nose-dive from around 50% down, most schools of thought advocate an uninterrupted/system- switched- off- recharge once the battery reaches 50% -ish.

Thanks for your help. Unfortunately, I don't think what you're saying makes too much sense. If i have an indicator for something, say temperature, it makes no sense to have it work correctly from say 100->50 degrees F and then when it reaches 50, it doesn't know the difference between 50 degrees and 0 degrees F. ;)

As for the advocated thought to turn the system off at 50%, I have never read that anywhere. I know you should never completely drain your battery, but no one ever said 50%...like I said, at 50% I still get 45 minutes or so. So you're basically saying I should shorten my battery life even further from 3 hours to 2:15? umm...don't think so :)

Has anyone else seen this precipitous indicator drop near 30% or so?

NYUarab, thanks for the beaker analogy. that's exactly what happens to me too. The water just rushes out all at once at around 25/30%. Good explanation.

Does anyone out there have a solution or has it happened to you?

bluetracker,

Thanks for responding. However, I have to agree with facted that your answer, while informative, sheds little light on the situation we're having. Your beaker/pebbles analogy is a great explanation of the loss of capacity in a battery; however, using your same analogy, the problem that I'm experiencing is that as I pour water from the beaker, everything goes fine for the first 3/4ths of the beaker, and then all of a sudden, all the remaining water gushes out at once.

And even *if* battery performance takes a dive after 50%, that still doesn't explain how it completely crashes after 75%....

What part are you having a problem grasping?

The battery monitor is a software program that is programmed to provide info on the basis of a set of conditions determined under lab conditions...real life ain't under lab perfect conditions.

Hey I've a temp monitoring system in my car that tells me the temperature outside is a certain number of degrees...now if I stopped the car and stuck a mercury thermometer out the window do you expect the two readings to match...no way Hosea. What I'm attempting to get through to you is that the program on your system is an INDICATOR only nothing more nothing less. If you really wanna know EXACTLY how long you have left to go on your battery, it would take a darned sight more equipment than a simple computer program to find out.

As for shortening the life of the battery by recharging it when it hits 50% or so, believe it, or believe it not, it's the way to go unless you wanna post in a few months that your battery isn't holding charge anymore. Draining the last ounce of power from a Li-Ion battery and then re-charging it does it no good at all and leads to it failing well b4 it should do. In fact if you drain it flat then the chances are it won't hold charge ever again unless it's re-energised using VERY expensive equipment and sometimes not even then.

http://www.hotcakes.com.au/tips_codz/tips_codez.htm has some good tips on battery care one such under the Discharging Batteries section is ...."You should avoid deep-discharging Li-Ion batteries".
Ok the site is basically about mobile phone batts but the principals still apply.

blue, thanks again for your replies, but I think that they're getting more and more off topic and useless. If you don't have an answer for us, that's fine, but tell us and don't try to talk about things that you don't comprehend so well.

As for the 50% discharge, like you said, you should never discharge a battery to it's "last ounce". However, 50% of a battery, is not it's "last ounce". That is not standard for any battery, period.

blue -- the part i'm having a problem grasping is how you can provide an answer that has nothing to do with the problem.

First of all, your analogy with the thermometer is completely off-base -- sure, the readings won't match exactly, but they will be highly correlated (do you need me to explain what a "correlation" is??).

As for the battery meter -- do you even know how it works?? sure, the time remaining may have been decided by some "boffin," but that's not how the percentage remaining is calculated. what **REALLY** happens is that the system is aware of the current capacity of the battery, the amount of power that has been discharged. It's really quite a simple calculation to determine what specific percentage of capacity is remaining given that information. sure, the windows battery meter doesn't give you (the end-user) that information, but there are plenty of freeware/shareware programs that will -- batterymon by passmark is a good example.

so -- before you start getting all hot and bothered/high and mighty, blow me. i know you fancy yourself out to be some sort of battery expert, but, please, get a clue.

Message Edited by NYUArab on 02-12-2004 01:12 PM

NYUarab: I've upgraded to the A09 bios from A05 so we'll see if that helps the problem at all. What bios are you using?

I'm on A09 as well... no difference made for me.

blue: go look up the definition of "abuse" and come back and tell me that me using my battery past it's "half-way" life is abusing the battery. When I bought my computer, I read all the things you have pointed to. I posted on teh forum and read all sorts of information on my battery. I have done what has been recommended. In case you didn't read what I wrote before, this problem I have mentioned has happened to me since the day I bought this computer. So enough about the battery abuse ok?

As for your comments:

1) I rarely run my battery below 50% becuase two classes worth of battery = about 50% and I know I can' tmake it through the 3rd, so I always recharge.

2) I always fully recharge my battery.

3) I almost never run my computer from AC for long periods of time. (maybe an hour here or there).

So given these facts and that my battery did the described behavior the first day I bought my computer, do you have any other brilliant suggestions?

 

 

Message Edited by facted on 02-12-2004 03:38 PM

not only are you illogical (never run a battery below 40%? Then why buy a laptop in the first place?), but a pedant. Keep on enjoying your ego-masturbation.

Enjoy BIOS version 10...I give in