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The manual for my new laptop clearly states that partial charge cycles of it's (Li-Ion) battery should be avoided. It recommends to always discharge to automatic shutdown and then charge back to 100% in order to prolong battery service life.

What could be the reason for this recommendation?

Are there circumstances where this would make sense?

Update

The (english) manual can be found here: http://download2.medion.com/downloads/anleitungen/bda_40055298.pdf

In section 7 on page 23 it says: "The battery should always be completely discharged before charging and then fully charged again to optimise the service life and performance"

Interestingly, I found there's a software pre-installed that allows me to set upper and lower SoC limits where to stop/start charging automatically.

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    \$\begingroup\$ Can you provide a link to that recommendation e.g. website or PDF? It would be interesting to read the context. Over the years, I have seen various battery charging recommendations which didn't seem to be "best practices", but yours seems particularly strange. As a counterpoint, here is a quote from a random laptop user manual which states the opposite: "Full charge or discharge is not required." I don't believe there is one universally correct answer, nor do I believe all user manuals :-) \$\endgroup\$ – SamGibson Oct 23 '16 at 10:34
  • \$\begingroup\$ @SamGibson Found the english version of the manual online now, please see my edit. \$\endgroup\$ – JimmyB Oct 23 '16 at 11:22
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    \$\begingroup\$ Thanks. As you see, their advice to always fully charge the battery, is not consistent with them also providing a utility to not fully charge the battery! I know of at least two "tier 1" laptop manufacturers who offer that SoC choice - one of which makes a "non full charge" the default option, advertised specifically to increase total battery life. I suspect (but cannot prove) that you are reading old advice, left in the manual from the days of NiCd / NiMH batteries. Perhaps ask them directly why they advise this? My research agrees completely with the answer from FakeMoustache (+1) \$\endgroup\$ – SamGibson Oct 23 '16 at 12:52
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In my opinion the advise of the laptop's manufacturer (to fully cycle the battery every time) contradicts general concensus that many partial charge/discharge cycles prolongs battery life.

See the tables on this page at Battery University

Maybe the battery in your new laptop is not a standard Li-Ion based one but I doubt that. If you add the brand and model of the laptop in your question we can maybe further investigate this.

But it looks to me as if that laptop manufacturer does not have a clue and is advising you something that is actually going to make your laptop's battery wear out sooner !

The explanation why partial discharges are better is that a very low or very high battery voltage (that voltage is proportional to the battery's charge level) puts a lot of stress on the battery. By keeping the battery voltage near the middle or around 50% to 70% charge level puts less stress on the battery making it last longer.

BTW it is recommended to do a full charge - discharge cycle every now and then, like every 3 months or so. This is not for benefit of the battery but for the charge level detection circuits in the laptop. This will help in more accurately predicting the remaining charge level in the battery.

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  • \$\begingroup\$ The user can not know the real charge and discharge levels of the laptop battery. It is very well possible that the bms manages the levels correctly and informs the user in terms of full and empty. \$\endgroup\$ – Decapod Oct 23 '16 at 11:50
  • \$\begingroup\$ @Decapod Battery level is always a guess. The only levels the user and battery management can know are full (100%) and the voltage at which the battery is assumed to be fully discharged (0%). Any value in between is a guess. The full level also depends on the manufacturer of the device. Some charge it to 4.3 V instead of 4.1 V to make the battery store more energy. But that comes at the cost of battery lifetime. 4.1 V would be a better value to prolong the life of the battery. This is for Li-Ion based cells of course. \$\endgroup\$ – Bimpelrekkie Oct 23 '16 at 11:59
  • \$\begingroup\$ Maxim and TI make LIPO fuelgauges. So a modern bms should be able to find the in between values, at least within margins. Maxim uses a coulomb counter. \$\endgroup\$ – Decapod Oct 23 '16 at 12:15

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