VN7-592G always switches off at exactly 24%

No, the percentages are set to 5% and 10%, which, I think, are the defaults.

You could have known this from my first posting, because I had explained that the computer switches off, instead of going into energy saving or hibernation. In fact, there is no option to tell the computer to shut down. Sensibly, there is only energy saving or hibernation.

Perhaps I should have mentioned that I am an experienced computer user and programmer.

I had recently repeatedly charged the battery only to 60%, except for the one battery calibration attempt I had already mentioned. Perhaps the built-in algorithm for the battery capacity is defective. I will find out by charging to 100% repeatedly. If that is the case I could keep charging the battery to 60% and set the critical battery level to 25%, as idiotic as this sounds. But the ***** would not be me.

Rockeraocao wrote: "Try tighten the screws on the bottom of the laptop."

Why do you think that could possibly help? Sounds a bit unlikely to me. Have you had any such experience?

Meanwhile I noticed that the battery percentage changes only in big jumps on my problem computer. For example, when I charge it fully, then stop charging and use it, the percentage stays at 100% for a long time, then it jumps to a lower value.

Does anybody know whether the responsible electronics are inside or outside the battery? I am asking, because I want to have a clue about whether changing the battery could possibly solve my problem.

I think this makes sense, because the battery needs cell balancing anyway, which is usually done by electronics in the battery box.

I have two VN7-592G laptops, so the next thing I will try is to swap the batteries and check whether the problem follows the battery.

The next thing I will find is probably that batteries are exempted from warranty. But let's see …

If you could see how the laptop is stowed behind the big screen when I'm not travelling, you would understand why I hesitated before doing it, apart from the general skepticism towards strange-sounding advice. Sometimes you get weird instructions in forums like this and have to decide whether they are reasonable or not.

Yours is reasonable, but I could not know before your explanation. Thank you very much for giving good advice!

Even after your explanation I have some doubts in my particular case, because a loose contact cannot easily explain why it always cuts off at 24%. We will see in a short time when I will run the battery down again.

I have just taken it out and opened it to see whether I could swap the battery. I might be able to do that, but I have given up at first, because opening and disassembling this laptop is too difficult and too risky. You cannot open it fully before you remove three flat cables, which are connected through very flimsy connectors with tiny parts, some of which fall down when you open the connectors. Each connector is differently designed.

The battery is connected through a 10-pole connector. This indicates to me that the charging and balancing electronics are on the motherboard, not in the battery. I have loosened and reconnected the battery, but have little hope that this fixes things. Again, we will see.

It seems that the manufacturers shoot themselves in the foot by creating monolithic, non-modular designs where the user cannot, for example, exchange the battery and where instead the battery is inextricably married to the motherboard. This may be slightly cheaper to manufacture, but creates more warranty cases and more displeased customers like me. I think the VN7-592G is too expensive to throw it away when the battery dies after three or four years, so it will incur further costs.

Anyway, I may have to find out whether this can be repaired under warranty. I would still have to swap disks, because it is my main computer which needs repair, so I have to use the other one while the primary one is in the shop.

The total cost of a technical fault like this is unreasonably high, if I count my time too. Have I made a mistake when I bought Acer laptops?

Apparently the problem is solved. I report it here just in case somebody else has the same experience.

I believe that the problem was caused by a combination of a defect in the laptop, probably in the ACPI code, and my charging habits. I charged it only to 60%. At one time apparently the percentage calibration was shifted such that instead of showing 0% to 100% the laptop "believed" to see 24% to 124%. But all values above 100 were always shown as 100%.

This meant that my attempts to calibrate the battery settings failed, because I stopped charging when 100% were displayed, believing that the battery was fully charged, which it was, in fact, not.

After noticing that the indicator showed 100% for almost an hour before going down to 99% and less, I did another calibration, but this time I kept charging the battery after the indicator reached 100%, until I was sure that the battery was completely full. Then I discharged the battery completely, and this seems to have done the trick. I am already down to 18%, and the laptop is still running while I am writing this message.

Thanks, everyone, for bearing with me. What do we learn?

1. Batteries may occasionally need a recalibration.
2. During the charging phase of the recalibration, be patient and wait for a longer time. Do not trust the percentage indicator.