Slightly OT: Battery usage

Slightly OT: Battery usage

[Johan Vromans]

Thanks to Rich Townsend's work I can now see the astounding speed at
which the Li-Ion battery of my Tavelmate degrades :-(.
Is there a usage pattern that minimizes this? For example, always keep
the batter maximally charged, or --the opposite-- always discharge fully
before charging?

-- Johan


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Re: Slightly OT: Battery usage

[Norman Urs Baier]

Am Montag 06 Juni 2005 11.16 schrieb Johan Vromans:
> Thanks to Rich Townsend's work I can now see the astounding speed at
> which the Li-Ion battery of my Tavelmate degrades :-(.
> Is there a usage pattern that minimizes this? For example, always keep
> the batter maximally charged, or --the opposite-- always discharge fully
> before charging?
>
> -- Johan
>

You might want to talk to some RC-Car or RC-Flight addicts, if I remember 
right latest theory is to store them at a third charged. 
But at what speed does your battery degrade and what is your current usage 
pattern. When did you do the last full cycle? 

Norman


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Re: Slightly OT: Battery usage

[Johan Vromans]

Norman Urs Baier <normanurs.baier-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> writes:

> But at what speed does your battery degrade and what is your current usage 
> pattern. When did you do the last full cycle? 

It was at 90-90% when I first got reliable readings (approx 1 month
after purchase). Now, 6 months and 89 cycles later, it is at 75%.

I do not have a fixed use pattern. Often it is connected to the
charger for most of the day, and used while discharging for a couple
of hours (approx. 20-25% of the charge).

-- Johan


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Re: Slightly OT: Battery usage

[Nils Faerber]

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Hash: SHA1

Johan Vromans wrote:
> Thanks to Rich Townsend's work I can now see the astounding speed at
> which the Li-Ion battery of my Tavelmate degrades :-(.
> Is there a usage pattern that minimizes this? For example, always keep
> the batter maximally charged, or --the opposite-- always discharge fully
> before charging?

That is really OT but anyway interesting to PM so let's continue this.

As to all I know about Li-Ion and Li-Poly batteries should:

- - not be stored fully charged, charge to 30%-40% and the store at a cool
place, like your food fridge, but always above 0°C!

- - not be charged to full all the time. All Li-* batteries like only to
be recharged after they have discharged for at least 10% or more (i.e.
max. 90% remaining). Before that they should not be recharged to full
again. Many notebook charging circuits do not honor this and kill their
batteries within approx. one year (my Asus L3C did this, my Fujitsu
Siemens Lifebook B-Series does not, IBM T42p does not, etc.)

- - be charged in at least two phases, first phase up to 75%-80% at full
charging current, after that only a very weak charging current should be
applied, like 10% of nominal current.

- - never be discharged completely, i.e. up to the point where the machine
switches itself off.

Every charge/discharge discharge cycle reduces your battery's life!


> -- Johan
CU
  nils faerber

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kernel concepts          Tel: +49-271-771091-12
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Re: Slightly OT: Battery usage

[Stefan Dösinger]

Am Montag, 6. Juni 2005 10:40 schrieb Nils Faerber:
> Johan Vromans wrote:
> > Thanks to Rich Townsend's work I can now see the astounding speed at
> > which the Li-Ion battery of my Tavelmate degrades :-(.
> > Is there a usage pattern that minimizes this? For example, always keep
> > the batter maximally charged, or --the opposite-- always discharge fully
> > before charging?
>
> That is really OT but anyway interesting to PM so let's continue this.
>
> As to all I know about Li-Ion and Li-Poly batteries should:
>
> - not be stored fully charged, charge to 30%-40% and the store at a cool
> place, like your food fridge, but always above 0°C!
>
> - not be charged to full all the time. All Li-* batteries like only to
> be recharged after they have discharged for at least 10% or more (i.e.
> max. 90% remaining). Before that they should not be recharged to full
> again. Many notebook charging circuits do not honor this and kill their
> batteries within approx. one year (my Asus L3C did this, my Fujitsu
> Siemens Lifebook B-Series does not, IBM T42p does not, etc.)
>
> - be charged in at least two phases, first phase up to 75%-80% at full
> charging current, after that only a very weak charging current should be
> applied, like 10% of nominal current.
>
> - never be discharged completely, i.e. up to the point where the machine
> switches itself off.
>
> Every charge/discharge discharge cycle reduces your battery's life!
I've seen a really good website about LI-Ion batteries, but sadly, I've lost 
the link :-(. It basically says the same things as Nils wrote, only with more 
details.

- Some Linux-Side hints:
There's a Howto how to extend battery uptime: 
http://www.tldp.org/HOWTO/Battery-Powered/index.html

- I've made the experiance(Acer TM 803) that hard drive standby can help A LOT 
to improve battery uptime. I can reach up to 5h 30 min with the primary 
battery only, compared to the advertised ~4h 30min.
I've tuned my memory mangement settings to avoid disc access, and I've never 
had any problems, except with gaming. It's annoying of if the disc goes to 
sleep and the game stopps 3 secounds to start the disc and load the sound of 
your enemy appearing.

- Lowering the display bightness also helps.

- Turn off / remove unnecessary hardware(wlan, bluetooth, cdrom). I like to 
leave my DVD drive at home and insert a wight saver module or a secound 
battery.

- Disable unnecessary logging, and enable DPMS. Lowering the cpufreq also 
helps.

- Li-Ion batteries are very sensitive to too much heat. This is not only 
important for storing the battery, a major factor is also the temperature 
inside the laptop while the battery is in use. So if you can configure your 
laptop to use less power you have a double payoff: It directly runs longer, 
and it's better for your battery because it's much cooler.

- My battery shipped with my Travelmate has lost 90% of it's capatiblity after 
1 1/2 year after ~500 recharge cycles.I've spent a lot of money into 2 new 
batteries(1 primary and one secondary battery), and when tuning your hard 
drive keep in mind that hard drives are not more expensive than batteries.

Cheers,
Stefan


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Re: Slightly OT: Battery usage

[Florian Hühn]

This link may also be interesting for you:
http://www.batteryuniversity.com/parttwo-34.htm
It's a verny nice site with a lot of infos on batterys.


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Re: Slightly OT: Battery usage

[Stefan Dösinger]

Hi,

> This link may also be interesting for you:
> http://www.batteryuniversity.com/parttwo-34.htm
> It's a verny nice site with a lot of infos on batterys.
Thanks, that's the page I meant. Bookmark set, I hope I'll not lose it any 
more.

--
Stefan


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Re: Slightly OT: Battery usage

[Karol Kozimor]

Thus wrote Nils Faerber:
> - - not be charged to full all the time. All Li-* batteries like only to
> be recharged after they have discharged for at least 10% or more (i.e.
> max. 90% remaining). Before that they should not be recharged to full
> again. Many notebook charging circuits do not honor this and kill their
> batteries within approx. one year (my Asus L3C did this, my Fujitsu

True, my original L3C battery is now at 25% of design capacity and it's
a fairly common practice to restart charging every time the power cord is
plugged in. It's good you name the brands that got it right though.

> Siemens Lifebook B-Series does not, IBM T42p does not, etc.)
> 
> - - never be discharged completely, i.e. up to the point where the machine
> switches itself off.

Except that given current laptop power consumption, the battery is nowhere
near empty when the voltage drops below the acceptable level and the
circuit is switched off. That said, any attempts at shorting will damage
the battery.
Best regards,

-- 
Karol 'sziwan' Kozimor
sziwan-DETuoxkZsSqrDJvtcaxF/A@public.gmane.org


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Re: Slightly OT: Battery usage

[Vasileios Gkanis]

Hi,

As I am not an expert on batteries usage, I need your expertise.
I have a laptop with a Li-Ion battery. The company told me that I should at 
least once a month fully discharge it and then charge it. But, from what I 
have read this is wrong and will deteriorate the battery.
Also, I read that the battery should be kept at 30% of its capacity in a 
relative cool environment. But, does this mean that if the laptop is always 
on power I should remove the battery.

I too have observed a decrease in the power capacity, but if it drops a lot, 
the battery will be recharged. I was told that this is normal. Also, I 
observed that the charging rate is not constant, and initially it is at the 
maximum value, but then it drops and gets at 10% of the nominal value. 

What is the definition of a cycle? How can I tell how many cycles my battery 
has? Is it wise to keep the battery on the laptop, when the laptop is on 
power?

Thank you,
Vasilis


On Monday 06 June 2005 05:31 pm, Karol Kozimor wrote:
> Thus wrote Nils Faerber:
> > - - not be charged to full all the time. All Li-* batteries like only to
> > be recharged after they have discharged for at least 10% or more (i.e.
> > max. 90% remaining). Before that they should not be recharged to full
> > again. Many notebook charging circuits do not honor this and kill their
> > batteries within approx. one year (my Asus L3C did this, my Fujitsu
>
> True, my original L3C battery is now at 25% of design capacity and it's
> a fairly common practice to restart charging every time the power cord is
> plugged in. It's good you name the brands that got it right though.
>
> > Siemens Lifebook B-Series does not, IBM T42p does not, etc.)
> >
> > - - never be discharged completely, i.e. up to the point where the
> > machine switches itself off.
>
> Except that given current laptop power consumption, the battery is nowhere
> near empty when the voltage drops below the acceptable level and the
> circuit is switched off. That said, any attempts at shorting will damage
> the battery.
> Best regards,


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Re: Slightly OT: Battery usage

[Stefan Dösinger]

> Also, I read that the battery should be kept at 30% of its capacity in a
> relative cool environment. But, does this mean that if the laptop is always
> on power I should remove the battery.
From the battery side of view, yes, but the battery really helps to secure the 
laptop against power failures while on AC power. Keeping the battery in a 
cool environment is useful if you have 2 batteries and you want to keep one 
for later use in a few years time.

See
http://www.batteryuniversity.com/parttwo-34.htm(general) and
http://www.tldp.org/HOWTO/Battery-Powered/index.html (more Linux specific)

> As I am not an expert on batteries usage, I need your expertise.
> I have a laptop with a Li-Ion battery. The company told me that I should at 
> least once a month fully discharge it and then charge it. But, from what I 
> have read this is wrong and will deteriorate the battery.
I can't judge on this, but in most cases, the battery is used at least once a 
month. If not, then the uprising question is if it's needed at all. If you 
don't use the battery at present, but you'll need it heavily in, say, 2 
years, then it may be best to remove it and store it seperatly. (Depending on 
how stable the AC power is). I had one power failure since I own my Laptop, 
and this was right at one of the seldom times when I removed the battery.

Keep in mind that companies tell you what's best for them. But on the other 
hand, there are other things than battery lifetime, and keeping the battery 
in the laptop is a good choice for the avarage users IMO. See above.

> What is the definition of a cycle? How can I tell how many cycles my battery 
> has? Is it wise to keep the battery on the laptop, when the laptop is on 
> power?
I don't know what exactly a cycle is, but AFAIK it means discharging the 
battery reasonably and reloading it. I've heard that Li-Ion batteries survive 
only 200 cycles, and my battery was at 1/3 of it's original capaticity after 
~400 cycles.

Cheers,
Stefan


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