Confused about Battery Threshold Configuration.

I've had my Thinkpad T61p for a week now and it's pretty much amazing! But what irks me is the battery. The first time I turned it on and charged it, it had 5+ hours of battery life while playing music and at a quarter brightness. Now, from a full charged battery it only gets 3 and a half hours?

So then I looked into battery configuration. People kept saying that batteries only have a certain number of cycles but that the optimal thresholds for the battery manager is 36%-40%. Theoretically, if thats one charge/discharge cycle, wouldn't it be detrimental to the battery because of its brevity? Are there even more optimal settings?

Edit: I have a 9-cell battery.

 

What battery do you have?

 

I personally don't know what the batter considers to be one charge cycle, but I have a feeling that it automatically adds it up.

For example. if you went from charging up to 10% to 35% four times, that would be a total of 100% charge/discharge, which would give you one charge cycle.

Another possibility could be there's a certain charge amount it has to pass in order to be considered a charge cycle. An example would be if that number was 60% and if you passed it and get to 61% and then back to 59%, that would be a charge cycle.

Was the 5 hours what the meter said or what you physically experienced with the battery? If it's what the meter said, then I don't recommend you go by that because most of the time it's accuracy is off.

 

what irks me a little bit is that the only source for that 40% charge info I've found has been the batteryuniversity link, and I'm not even sure where his information is obtained from (I had a quick glance over bibliography but nothing stands out, so maybe his own experiment; nevertheless I'd like to know more about it)

I'm curious as to what happens to capacity when the battery is maintained at BELOW 40% charge.

Not only that, but it recommends to avoid 'deep' discharges. How deep is deep? Would it be preferable to use a battery from say 40% to 10%, or from 70% to 40%?

The 40% charge thing seems similar to the 8 glasses of water myth. Everybody says it but where exactly does it come from and how was it validated?

 

40% charge was a conclusion of testing which charge setting was optimal for decreasing the battery deterioration process as well as on-the-go use. At 40%, the temperature of the battery was mantained at a minimum temperature and one could get at least a good hour out of that.

A deep disharge would be going down to ~2-3% and then charging back up, which is basically like a complete drain.

 

Well the original 5 hours was my first time turning on the laptop but the 3 and a half hours was taken from the meter. I guess the meter can't be trusted because this morning it said I had 2 hours left at 80% charge.

 

And I believe the meter estimates time remaining based not only on the current charge left in the battery, but also on how you've been using the laptop the last few minutes. If you've been booting up or looking for wireless signals, it's been drawing a fair amount of use, and would therefore show less time remaining from the current charge. If you've only been typing, then the machine is spending most of its time waiting for input, and you'd see more time remaining from the came battery charge.