Reduced battery capacity

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Reduced battery capacity

Postby harshad1 on Wed Jun 16, 2010 1:59 pm

Hi,

I just noticed this in gnom-power-manager's battery statistics page:

Energy 54.0 Wh
Energy when empty 0.0 Wh
Energy when full 54 Wh
Energy (design) 77.0 Wh
.
.
Capacity 70.1%

Does this mean my battery has lost capacity? Is there any program that will let me re-calibrate this?

In general, is there anything short of getting a new battery I can do about this?

I have a Dell Studio 14z.... Its only about 10 months old....
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Re: Reduced battery capacity

Postby grimdestripador on Wed Jun 16, 2010 5:26 pm

In general you have 200 charge/recharge cycles before a battery is near 50% of original capacity. The exact number depends on how you leave it charged. If you leave a Li-ion battery in the discharged state (overnight, storage, you always run it dead), then you are abusing the battery, depending on the time you left it discharged. This is different from most advice from Nickel-Metal-hydride, which can recover some lost capacity by "cycling" the battery. Cycling does not improve Li-ion performance, but does increase the accuracy which it reports (pretty pointless). Consider this, If you drain you battery every day at work, drive home, then charge it, it would be dead (<50%) within a year. If rather you, Go to work, work for 4 hours, charge for 1 hour, then use for 4 hours, then charge on the way home. then after a years time , your battery would be near 80%. And the last is shelf life of Li-ion batteries, say you bought 2 batteries with your laptop, one for use, one extra which is saved for when the first dies. After a years time, given the above scenario, the used battery will be between 50-80%. If the empty battery was left in packaging, then through the years time, it has lost its charge to due 'leakage current', effectly reducing it to storing it at 80-90%. When the battery is stored while not having 100%, chemical decay of the electrodes and the electrolytic occurs (lithium is pretty reactive).

Best case it so use two batteries such that they stay near 100%.

These are just numbers pulled from ether-space guided by rules of thumb,
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Re: Reduced battery capacity

Postby harshad1 on Thu Jun 17, 2010 3:04 pm

Well, I think I fall into category number #1. Only its college and not work :)

I regularly let my battery discharge until it has just a few minutes of battery life left.... Hmmm... I still get ~3.5 hours on a full charge. I guess I can go for a while as long as I don't abuse the battery further :(

Thanks for the info.
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Re: Reduced battery capacity

Postby DrHu on Thu Jun 17, 2010 6:45 pm

On every battery recharge, If you can't control your batteries charge rate to approx 80% of full charge, then you will have a dead battery in about 1/2 the normal time..
--so instead of having a battery that runs/works for 4-5 yrs, you will only get about 2 years use, before it won't charge again, then its a search for a possible replacement, and battery replacements (if available) tend to be one of the more expensive parts of a notebook.

Which brings up an interesting point: if you buy a notebook or refurbished notebook from someone or some store, how do you know how long that battery will now last
--you are unlikely to be able to get a straight history or a believable one from the seller/vendor
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Re: Reduced battery capacity

Postby abeyclinton on Fri Jun 18, 2010 8:19 am

Generally the main reason for removing the battery is to reduce the heat from it. The battery life may be reduced slightly, but not to any significant extent. You all have given very nice suggestions and I agreed with it.
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