# battery lifetime decreasing very fast

## barul

Hi there.

On last Monday, I bought a new laptop, but "acpi -V" tells me that the whole capacity is at 98%. On Monday evening, it was at 100%.

Can it be because of I never let it discharging completely ? Do you have some tips to save my battery life?

Thanks in advance.

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## Pearlseattle

Sorry, can you pls. explain better your problem? Didn't get the point.

About the battery: notebooks usually charge it only when the capacity is below 95% - nothing happens when it is still between 95 and 100%.

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## gerdesj

 *Cr0k wrote:*   

> Hi there.
> 
> On last Monday, I bought a new laptop, but "acpi -V" tells me that the whole capacity is at 98%. On Monday evening, it was at 100%.
> 
> Can it be because of I never let it discharging completely ? Do you have some tips to save my battery life?
> ...

 

I've never used acpi but have a look in /proc/acpi/battery/BAT0/info and state.  

In info there is a "design capacity" and a "last full capacity".  I suspect that the 98% is the ratio of these.

Against "battery type" you probably have LION or Lithium ION. See this: http://en.wikipedia.org/wiki/Lithium-ion_battery, under Advantages there is listed "no memory effect".

So I would suspect that all you are seeing is that batteries are sent out provided their charge is within a certain tolerance of the design charge.

I see the following on my Dell Studio 17:

```

Info:

present:                 yes

design capacity:         5200 mWh

last full capacity:      4513 mWh

battery technology:      non-rechargeable

design voltage:          11100 mV

design capacity warning: 451 mWh

design capacity low:     0 mWh

cycle count:              0

capacity granularity 1:  100 mWh

capacity granularity 2:  0 mWh

model number:            Dell

serial number:           2301

battery type:            LION

OEM info:                SIMPLO

State:

present:                 yes

capacity state:          ok

charging state:          charged

present rate:            1 mW

remaining capacity:      4513 mWh

present voltage:         12373 mV

```

I suspect that programs like Powerdevil (KDE) etc look at the charging state for 100% and then compare remaining capacity against present voltage to show their percentage.

I don't know what acpi does  :Cool: 

Cheers

Jon

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## Logicien

One time I had a battery that was just below the design capacity when fully charged. I reboot and remove the AC cable and let the Grub menu being displayed until the laptop shut down because the power of the battery was to low. Than I put the cable in again. After the AC power charged the battery fully, the remaining capacity of the battery was at the design capability. This is possible when the battery is new. With time, I think there's nothing that can make the battery loose capability more or less, depending on it's quality and the use you make of it. 

Some says that a battery must be completely discharged and fully recharged from time to time, like one time a month, others says that less you use it (under 85%), better it is. I am open to new espertises. I can say that my actual battery is at the design capacity when fully charged since I bought it 6 months ago. I use it very few.

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## gerdesj

 *Logicien wrote:*   

> Some says that a battery must be completely discharged and fully recharged from time to time, like one time a month, others says that less you use it (under 85%), better it is. I am open to new espertises. I can say that my actual battery is at the design capacity when fully charged since I bought it 6 months ago. I use it very few.

 

LION batteries (Lithium ion) don't have memory effects, they just degrade with time.  Mine is around 18 months old and does not hit the design capacity any more. 

I think NiCd (NICAD or Nickel Cadmium) do http://en.wikipedia.org/wiki/Nickel-cadmium_battery have memory effects.

I believe most laptop batteries have Li ion cells in them nowadays - they are the exploding ones - Mmmm exploding Apples!

Cheers

Jon

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## Logicien

I just Google a bit to read that discharge/recharge completely a battery is applyable to Nickel Cadmium ones. Apply that to Lithium ion ones can dammage them and even worst. So, make your own searches and only do things "if you know what you do". I often read that in Linux world. I appreciate the philosophy and I try to keep it in mind.

 :Very Happy: 

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## dE_logics

 *Logicien wrote:*   

> I just Google a bit to read that discharge/recharge completely a battery is applyable to Nickel Cadmium ones. Apply that to Lithium ion ones can dammage them and even worst. So, make your own searches and only do things "if you know what you do". I often read that in Linux world. I appreciate the philosophy and I try to keep it in mind.
> 
> 

 

Ni Cd batteries suffer from a problem called 'memory effect', they need a complete discharge to put their cycles back in place.

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