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freeborn

laptop battery life span is fixed time or cycle?

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That depends on the type of battery technology used in the laptop, though I believe all the recent ones are Lithium Ion.

Lithium Ion batteries loose a fixed percentage of their capacity each year as they age, regardless of how they're used. On top of that, they benefit from frequent charging and not the deep cycle discharge/charge that's most benficial to NiCads.

More Info Here:

http://en.wikipedia.org/wiki/Lithium_ion_battery

-Chris

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Hiya, bought a new laptop ibm thinkpad T43 and wonder whether the battery life depend on the no of recharge cycle or is it fized no of years? Because if it depends on recharge cycle then i may as well take it out when i use power supply so that it can sustain longer. Thank!

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Bascially, Li-Ion batteries are only good for roughly three years regardless of how often they are used. Even just sitting on a shelf they will degrade. As shoemakc pointed out, they like to be topped off frequently rather than deep-discharged. In fact, most Li-Ion cells are electronically protected from discharging under 2.4 V per cell as it would cause permanent damage.

On the other hand NiCad and NiMH should be deep-discharged occasionally (one in every ten or twenty cycles) so as to maintain capacity, but frequent deep discharges will hurt them also. NiMH are much more sensitive to overcharging than NiCad. As for shelf life, provided they are stored in a charged state, and recharged every few months to compensate for self-discharge, both chemistries can last ten years or more. I have 30-year NiCads which are still good, for example. NiMH may be less long lived. It hasn't been around long enough to know one way or the other.

All battery chemistries have a finite number of charge-discharge cycles irrespective of their shelf life. The gentler the recharge (i.e. less heating), the more cycles you get. Under ideal conditions (shallow discharge, occasional deep discharge) NiCads have gotten tens of thousands of cycles.

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I am using 7 year old Li-ion cells, so they still work after many years but capacity falls to less than half of new after ~3 years no matter how many recharges. NiMH can last ~3-500 recharges and good old Ni-Cad over 1000, depending on how you charge them. Those 15 minute chargers will reduce life to <200 charges, but this may be worth it considering the time saved.

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Hiya, bought a new laptop ibm thinkpad T43 and wonder whether the battery life depend on the no of recharge cycle or is it fized no of years? Because if it depends on recharge cycle then i may as well take it out when i use power supply so that it can sustain longer. Thank!

211918[/snapback]

FYI, to SR members approximately 6hrs after the banning of SR member DUT, SR forums started to falter :ph34r: , coincidence or conspiracy? An X-file ? ;).

No but on a serious note, pgp had posted this same topic 6 times in within 60 minutes, so we can speculate pgp had problems with the forums when they started to altogether stop working. SQLdatabase error messages. Mods presumably (we hope???) removed most of the duplicate threads that had no text, but unfortunately did not remove one of these threads before everyone started to reply... to the wrong thread.

If they had read this thread 1st, they would have known we are speaking of 18650 sized Li-Ion battery packs in the Thinkpad.

Toshiba is/has developed a very interesting type of quick-charge Li-Ion battery that may someday make it into laptop applications. Virtually no loss of capacity after 1,000 discharge/charge cycles!

Toshiba’s Fast-Charging, Long Life Li-Ion Battery

For the present, standard consumer grade Li-Ion batteries used in laptops may fail after only 3 years regardless of how you treat them, mine failed at just about 3years, rapidly lost capacity until they would hold no charge at all. Other people get lucky and their batteries last longer but capacity drops off. How much capacity loss you are willing to accept is a trade off balanced against buying another expensive replacement of higher capacity.

See this article (I read anecdotal evidence that removing the battery while running of the AC power supply will increase batterlife...it can't hurt to do this, if you are not lazy like me ;) ):

You will note this article written by someone who knows something about Li-Ion technology states a higher low voltage level for the cells circuits to turn-off the cell, than what others have stated.

http://www.ecnmag.com/article/CA378860.html

It makes little difference to pgp, the question was as to removing the battery pack from charging while the laptop is running off the PS. I again, it could not hurt; but I have not seen conclusive evidence this materially extends a battery only designed to last about 3yrs. from the date of manufacture.

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Thanks for all the replies, and yes I tried to post this message several times but always got an error. Didn't realise that e message has been actually dup posted several times already :)

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