Why Lenovo recommend to charge battery to 70% instead 100%

[Pawelk198604]

I was advised to turn on setting to disable battery charging when is 65-70% but why and how it's increase battery life span.

[Ralathon]

It's due to the way Lithium Ion batteries work. The internal membranes get damaged (dendrites start growing on the surface) when you charge them to 100% or discharge them to 0. So most batteries come with internal limiters to make sure they always stay between 20 and 80%. In your case the laptop needs to take care of it apparently. Anyway, that's why you should never charge your Li-Ion batteries to 100%.

[problemecium]

^ The dendrite thing is news to me, but otherwise I concur. At least in theory, Lithium ion batteries last longer when placed under less "stress" by charging up or discharging a large amount (unlike "traditional" rechargeable batteries), and it's possible to permanently damage or ruin a Lithium ion battery by overcharging it or draining it all the way to zero volts (but don't worry too much over that because your laptop will be unable to stay on and will shut off long before the battery reaches "absolute" zero).

[magnemoe]

^ The dendrite thing is news to me, but otherwise I concur. At least in theory, Lithium ion batteries last longer when placed under less "stress" by charging up or discharging a large amount (unlike "traditional" rechargeable batteries), and it's possible to permanently damage or ruin a Lithium ion battery by overcharging it or draining it all the way to zero volts (but don't worry too much over that because your laptop will be unable to stay on and will shut off long before the battery reaches "absolute" zero).

Yes an laptop has very strict voltage requirements, you can get weak but useful light out of an flashlight with almost empty batteries but an laptop will shut down if power much below default voltage.

As for oversharging I would think the electronic in the batteries took care of it, too have additional software shutoff might extend battery life out over the required 2 years and might be just as well if you don't need to run it a long time on battery anyway.

[Sirrobert]

It's due to the way Lithium Ion batteries work. The internal membranes get damaged (dendrites start growing on the surface) when you charge them to 100% or discharge them to 0. So most batteries come with internal limiters to make sure they always stay between 20 and 80%. In your case the laptop needs to take care of it apparently. Anyway, that's why you should never charge your Li-Ion batteries to 100%.

So wait. In normal laptops, when it says 100% battery, it's actuall 80? And it shuts down at 20%?

[lajoswinkler]

So wait. In normal laptops, when it says 100% battery, it's actuall 80? And it shuts down at 20%?

No, it's 100%. But there is usually a software that comes with the laptop's motherboard drivers that offers you different energy management. I use battery saving which holds charge at 60%.

[Camacha]

So wait. In normal laptops, when it says 100% battery, it's actuall 80? And it shuts down at 20%?

There is not really a true 100%. That 100% is a value that gets established in a lab after testing and it will, of course, be appropriately scaled to that battery performance and life are optimally balanced.

In theory there is an absolute chemical 0 and 100%, but those are not really feasible in real life.

[magnemoe]

There is not really a true 100%. That 100% is a value that gets established in a lab after testing and it will, of course, be appropriately scaled to that battery performance and life are optimally balanced.

In theory there is an absolute chemical 0 and 100%, but those are not really feasible in real life.

Correctly, however battery life has to reach some legal requirements, I think its 2 year in EU, yeas getting the extra 20% will void guarantee, one thing I loved about my old thinkpad was the battery change mechanism, it felt like the eject magazine on an assault rifle, it should have an 1 minute internal battery for swaps, it would be cool to do during an meeting.

The others see the three other ready batteries in the bag and kind of give up. (lots of important business decision has been done fast 17:45 om a Friday usually by people who fly back on Sunday anyway and get an serious bonus for fixing the deal)