Re: Question on lithium ion batteries.

I should probably add,
Really new, and perhaps better quality laptops /may/ have better charge 
circuits, that won't try and charge a 95% charged battery again, thus 
saving it from the early death suffered from leaving the battery in a 
wall powered laptop.
Generally speaking you should expect ~30% battery capacity loss after a 
year, and ~50% or more after 2 years in a battery that has been looked 
after but still used, better quality cells will fair better than this.

On 24/01/15 01:44, Jake Anderson wrote:
> over discharging will cause damage
> over charging will also cause damage (but less so)
>
>
> If the laptop is going to sit on your desk plugged into power for 90% 
> of its life, run the battery down a bit (like to 50% charge), then 
> turn the laptop off and take the battery out (assuming you want it to 
> last when you go on the road), Once every few months, charge it up, 
> run it down to about 20%, charge it again, then run it back down to 
> 50% and take it out. Leaving the thing on charge all the time will 
> generally kill it.
>
> The more you discharge the battery the less lifespan it will have, so 
> if you can charge it at 50% all the time (assuming you are a regular 
> user of said battery) it'll last longer than if you discharge it to 
> flat every time. I reckon with modern batteries 30% charge is probably 
> a good cutoff point in terms of cycle life vs calendar life.
>
> Every once in a while running it down to flat or nearly so then 
> charging again isn't a bad thing, it'll slightly increase the capacity 
> (this is a real effect, we see it on unpackaged lipoly cells we use in 
> robots, its not the memory effect, its something else, but a cell 
> thats been sitting for a while or only lightly used will gain ~30% 
> capacity with some "exercise") and more importantly let the fancy 
> chips in the battery re-calibrate their calculation of the capacity of 
> the battery.
>
> generally discharging or charging cause damage, but the damage gets 
> worse the further from the middle you go, when they want a really long 
> life from cells, they run them just around the middle range, like from 
> 40% charge to 80% charge, with consumer lithium cells you will 
> generally hit calendar life issues before cycle life if you don't go 
> nuts.
>
>
> btw the memory effect is a specific thing for nicad cells that was 
> discovered when the batteries were discharged to *exactly* the same 
> point over and over again (say 20% state of charge), then when 
> expected to discharge past that point they had practically no 
> remaining capacity.
> http://en.wikipedia.org/wiki/Memory_effect#True_memory_effect
>
> On 23/01/15 18:15, William Bennett wrote:
>> Menno,
>>
>> Thanks for the information.
>>
>> I will add this: you'd be surprised how many computer experts,
>> professionals included,
>>
>> labouring under this misapprehension.
>>
>> I asked around because I had been told of the existence of “memory”, but
>> felt that the
>>
>> manufacturers should know what they were talking about.
>>
>>
>> William.
>>
>> On Fri, Jan 23, 2015 at 4:42 PM, William Bennett <[email protected]>
>> wrote:
>>
>>> So, having absorbed, from my friends, the dangers of partially
>>> recharging a  lithium-ion battery due to “memory”, I read the insert 
>>> that
>>> came with the new laptop battery:  –
>>>
>>> “Recharging a partially charged lithium-ion does not cause harm because
>>> there is no memory. Short battery life is mainly caused by heat 
>>> rather than
>>> charge/discharge patterns.”
>>>
>>> Um, who's right?
>>>
>>> William Bennett,
>>> Armidale.
>>>
>

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