Terrible Battery Life... done my calibrations and energy saving steps...

Hey all,

I have a 1 yr old Macbook Unibody (13.3"- Late 2008 model).

I have the 2.4Ghz version.

Anyway, here's what I have:

Original Batt Capacity = 4100mAh.
Current = 3953mAh (can dip to 3800 at times)
Battery Load cycles = 58

I'm currently running on batteries. I only have my browser opened along with some widgets and WIFI. I've taken all energy saving steps as well (lowest possible brightness on screen and keys) Currently sitting on 86% w/ 3 hours left.

I use to be able to get as much as 5 hours on 100%. At the rate I'm discharging, I'm very far from that.

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Lately, I've been running Boot Camp a lot. Shutting down and rebooting straight into Windows. In fact, today is really the first time I've been using OSX. Could this in anyway affect the battery readings?

I did a calibration last week and I'm not sure if it'd be a good idea to do it again today. I don't want to kill the batteries.

Anyway what could I do to salvage this... Based on Coconut Battery, I'm not too far off from the original capacity. I just don't get why the batt is discharging that quickly...

Any insights would be appreciated!

Thanks!

 

I wouldn't worry about it too much. Just use the laptop in OSX as you normally would and set up a timer to determine the actual usage time it gets. Come back and post the time and then we can figure out how to proceed. I find my battery guage jump around quite a bit. For instance, in the last 10 minutes my guage was showing anywhere from 3hrs left to 9:15 left (at 95%).

 

The estimation of your remaining time isn't just based on the battery capacity. For one, it is slightly eccentric in general. For two, it is based on your (short term) battery drain rate.

In other words, if I am doing a processor intensive task or my HDD is spinning and I have 100% battery life remaining, and you are idling at 50% capacity, you *should* get a longer hour reading than me...

Point being, run the timer to see how long your battery actually lasts. Don't trust the remaining time indicator if you are being picky about the battery life, because that indicator simply isn't accurate enough.

On a side note, your battery is rated for 5 hours. Your maximum capacity is ~95%. You are currently at 86% of your max. So .86*.95 = ~4... so that would be a good target with wifi on, bluetooth off, screen brightness pretty low (maybe minimum)... you can web browse or go idle or type documents, etc.

 

First you shouldn't discharge the battery fully.
It kills the capacity.
The reason they chose Lithium-Ion because it is not meant to be discharged completely.

 

Yup... that's true. but it's impossible to discharge the battery fully unless you purposely short circuit the battery. The protection circuit will disconnect the battery way before the battery is even close to fully discharged. So it's perfectly save to discharge the battery to 0% if you want.

 

That's not terrible. My macbook is at the same situation, and I asked the same question earlier, all the replies said it is normal. With a late 2008 macbook, that is pretty much what the battery can give us, and the newer version macbook pro has a better battery life.

 

Hello All,

I believe that the battery in the new Macbooks is actually Li-Poly or Lithium Polymer. It is entirely a different technology than Li-Ion. Please see here: http://www.apple.com/macbookpro/battery/
And, no you cannot fully discharge Li-Poly batteries in normal use. Discharging even one cell of a Li-Poly battery below its specified min voltage renders the pack too dangerous to charge. Any other RC Heli Pilots here?

jwb

 

lithium polymer batteries are actually a type of lithium ion... basically the same tech... just design differences can help shape them easier and make them lighter, which is why remote control aircraft have used them a long time... theres barely any difference other than that.