Lenovo laptop energy management and should it be plugged all the time?

Tony Tony

Nov 5, 2014
So, i have this lenovo ideapad z400 laptop that have energy management software that allow me to make the laptop charge only to 60% and then not charging, i find it was good but after using a while (in windows 8.1), it just like my laptop can't recognized very well the battery capacity.

100%-30% is decreasing normally but after it reach less then 30% it suddenly jump to 7% and warn me to do charge or sometimes sleep/shutdown my laptop.

Luckily there is also calibrating option in that software that can calibrate the battery and make it right... but it is tiring task since it need to charge and discharge completely

and i ever using other laptop before but never experience all this problem, i have conclusion maybe because of option to only charge to 60% and then i get another new question now, if i'm not using that software to limit only charge 60%, is it safe for me to charge to 100% and leave it plugged in? (since i use my laptop all day and this laptop battery life only around 2-3 hours)


Jul 3, 2012
You can charge it to 100% and keep your laptop plugged in.
Keeping it plugged in while using should actually increase your battery life in the long run. Just remember to discharge it to around 30% once a week.
All batteries' life span depends on the number of times it is discharged and recharged, so if you are putting it through more cycles of recharging and discharging by using it on battery frequently, it will degrade faster.
While i agree it is better to keep the charge at around 75 - 80% and discharging it to 40 %, this gives you a very narrow window to work, is impractical and becomes an irritant.
Also, if you see all the articles as posted above, you will notice that they advise to charge it to 70 - 80% and then put the recharge cycle life at a certain figure and for full charge, a somewhat lesser figure. But what they do not mention / consider is that a 100% battery will give more work hours than the 70% charged one and thus you will have to charge it lesser number of times for the same amount of work. And more recharge and discharge cycles with the 70% means lesser life span.
Also, consumer grade batteries show asymmetric calibration and discharging from 100% to 70 % (30% discharge) than 70% to 40% (same 30% discharge), as you must have noticed in laptops to cellphones. So, the 100% battery will provide you with even more work hours than a linear discharge model would suggest.
Also, I am a bit skeptical about the work carried out by battery university as stated here
from where the above article takes reference, as it says that if the Depth of Discharge is 10%, it will give 3 - 3.5 times more of discharge cycles than a 50 % charge, as it is a known fact that discharging a battery below 20% - 15%, very rapidly decreases its life and that is why in most laptops, cellphones etc. there are default battery saver features to avoid further degradation, so take the research with a grain of salt. Not to mention a 10% charge is super impractical.
What you can ensure however is to keep your laptop in a relatively cool environment as this will reduce both battery consumption and in turn battery wear.
Hope this answers all your questions :)

It sounds like you simply use the laptop at home keeping plugged into the AC outlet all the time. Since you cannot remove the battery from the Z400 laptop, it is best to only allow it to charge up to 60% and leave it alone. The energy management software is purposely only allowing the battery to charge to 60% to help prolong the life of the battery.

The reason is because as the battery is charged near it's maximum capacity a chemical reaction start to occur. The high charge causes something referred to a lithium ion plating. Lithium ions is allows the battery to hold a charge however, when the charge is too high the lithium ions starts to clump together to form lithium ion plates. When this happens the battery capacity begins to drop because the lithium ions that have started to clump together will no longer hold a charge. The result is that the battery life will begin to drop and the more the battery is kept near a full charge, the faster the battery life will decrease.

When you know you are going to be using the laptop away from the AC outlet, then at that point you manually override the energy management software to allow the battery to be charged to 100%. That way you can use the laptop for as long as possible. When you return home and plug the laptop to the AC outlet again for a long time, then allow the laptop to charge to only 60%.

The "calibration issue" you are having seems to only be a side affect of the energy management itself. Yes, it sounds like it is annoying, but the flip side is that it prolongs the useful life of the battery so just allow the battery to charge to 60%. Simply consider it as a maintenance you must do one every couple of months. The IdeaPad Z400 is known to have poor battery life even when new so 2 - 3 hours of battery life on a full charge sounds about right; depending on what you are doing.