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G14 battery wear

masi0
Level 7
Is it normal, than in the condition where laptop is mostly used with the AC power and only accoasionally running on batttery, the battery wear fluctuates around 5%?
I have read some articles about it, but did not found a clear explanation.
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2 REPLIES 2

maximo58
Level 7
Yes it is normal for the battery to wear constantly when the laptop is always plugged to AC, that's because the system is trying to keep it fully charged at 99%+ which puts a high voltage on the battery (4.2v+-) and that what produces the continuos wear, you could control the maximum charge with a software for example to 60% and that would reduce the wear a lot because the battery need less voltage to maintain 60% charge, would be better yet if one could control that from the laptop bios so no software install should be necessary.

It's actually the lithium-ion chemistry, rather than the trickle maintenance voltage required to maintain the charge. The cells are continuously degrading from the point where the chemistry is first activated. The degradation is slowest around 50-60% SoC (State of Charge), fastest at 0% or lower (0% SoC isn't actually empty), but also faster at 100% or higher. If you are storing them on a shelf, about 60% is optimal, but that's not practical for something like a laptop where you want on demand usage. Very low state of charge (below nominal 0%) is dangerous because the copper electrode dissolves in the chemistry, then replates if recharged, potentially leading to short circuit and fire; that's why batteries brick themselves and refuse to charge after overdischarge. Overcharging is also problematic, but doesn't occur so easily due to the charge controller cutting off at a safe level.

Cycling (charge, discharge, charge, discharge, ...) will shorten the life faster than just maintaining them at 100%, with the cells typically having around 500 to 1000 full cycles before they drop below 80% capacity (that varies significantly based on application and the charge/discharge rates).