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19 Posts

04-28-2021

Netherlands

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  • Message 11 of 31

Re:P14s severe battery drain when powered off

2021-05-05, 8:34 AM

OK thanks for the info.

 

It seems as though after I've once 'disconnected the battery' via the BIOS, things have changed. During the disconnection no battery charge was lost, which is good. After this, I once more reset the BIOS settings to default to start a settings isolation research.

 

With the default settings applied I measured the battery charge state a couple of times over the course of about 18 hours and only a percent of battery was used -- this is hopeful. I'm at a loss why this wasn't the case before when I did the exact same test (only before I once fully disconnected the battery). During the measurement I have the laptop completely powered off, not connected to anything.

 

I'm now in the process of doing this measurement over and over but changing a single setting at at time to determine if anything changes.

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42 Posts

02-24-2021

United Kingdom of Great Britain and Northern Ireland

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  • Message 12 of 31

Re:P14s severe battery drain when powered off

2021-05-05, 8:37 AM

If you disable the battery in BIOS, are you still able to use the laptop on AC power?

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19 Posts

04-28-2021

Netherlands

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  • Message 13 of 31

Re:P14s severe battery drain when powered off

2021-05-05, 9:05 AM

Hi Simon,

 

No, the disable battery feature is for long-term storage of the device. It decouples the battery, leaving it virtually disconnected. The BIOS is running off a supercap/little battery just keep the contents for a couple of days, but you're not able to turn it on via the power button. To reconnect the battery and startup the device once again, you must connect AC power.

 

For long-term storage, it's best for a Lithium battery to be charged about half way and be fully disconnected to prevent any drainage.

 

I tested this feature to rule out any battery-specific issues.

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42 Posts

02-24-2021

United Kingdom of Great Britain and Northern Ireland

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  • Message 14 of 31

Re:P14s severe battery drain when powered off

2021-05-05, 9:10 AM

I'll be interested to find out if you get to the bottom of your problems and find a cause.

If I don't use my Lenovo for one day, then it loses about 1-2% battery when off; however, if I don't use it for 3 days or more then the battery drain is much more - I lost 30% battery over a 4 day period even though the laptop was completely shut down. I've disabled all relevant settings e.g. fast start up, USB charge when off, etc but haven't got to the reason why yet!

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19 Posts

04-28-2021

Netherlands

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  • Message 15 of 31

Re:P14s severe battery drain when powered off

2021-05-05, 10:37 AM

Ha...that's interesting...because I'm now testing only for ±12 hours per test. Let's see if my conclusions still hold for three days or longer then. Good one.

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19 Posts

04-28-2021

Netherlands

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  • Message 16 of 31

Re:P14s severe battery drain when powered off

2021-05-06, 19:41 PM

OK, I'm still testing, but here's an intermediate result:

 

Fully charged the laptop on the 4th in the afternoon. Then, checked every ±8 hours by simply powering on the machine until the login screen to check the battery percentage and then immediately power off again. Booting from the moment the power button is pressed literally takes about five seconds, then checking + powering down takes another few seconds making the system being powered on in a check for about 15 seconds at most. In between the checks the system is fully powered off.

 

I would say a battery percentage check this way possibly costs almost nothing but let's say it costs a percent. That will make up for a maximum of about four percent per day just for the checks.

 

First I checked with default BIOS settings loaded:

  • 20210504 - 14h00: 100%
  • 20210504 - 22h00: 99%
  • 20210505 - 08h00: 98%
  • 20210505 - 14h00: 95%

OK, that was acceptable. Still remarkable, but at least acceptable.

 

Then from there on I changed the BIOS settings from default (disabled "Always on USB" -- which is what I don't need, and set "Sleep state" to "Linux" -- which is what I run):

  • 20210505 - 14h00: 90% (apparently the mere minute I spent in the BIOS cost me 5% of battery...)
  • 20210505 - 22h00: 90%
  • 20210506 - 09h00: 86%
  • 20210506 - 19h00: 77% (Uhhhhh.....seriously? Why???)
  • ...

I'm starting to doubt even whether the battery reading itself is wacky. The sudden jumps and plateaus are just..weird -- a linear decreasing percentage I could understand, not this.

 

...to be continued... :-/

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42 Posts

02-24-2021

United Kingdom of Great Britain and Northern Ireland

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  • Message 17 of 31

Re:P14s severe battery drain when powered off

2021-05-06, 20:19 PM

Interesting. This is very similar to what I experience and when the laptop is off (although I’ve not done the testing you have).

It’s strange that, like you, my battery discharge is non-linear and increases the longer the battery is off.

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19 Posts

04-28-2021

Netherlands

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  • Message 18 of 31

Re:P14s severe battery drain when powered off

2021-05-09, 20:18 PM

Ok, here's the extension of my experiment results:

  • 20210505 - 14h00: 90%
  • 20210505 - 22h00: 90%
  • 20210506 - 09h00: 86%
  • 20210506 - 19h00: 77%
  • 20210507 - 01h00: 72%
  • 20210507 - 09h00: 71%
  • 20210507 - 17h00: 64%
  • 20210508 - 01h00: 64%
  • 20210508 - 09h00: 64%
  • 20210508 - 17h00: 57%

And that's where it ends. I'm on the road and need to work on the machine now, so I can't leave it powered off any longer.

 

Summing up the results so far:

  • The experiment ran for little over three days, for exactly 75 hours.
  • The machine was powered on 10 times for about 10..15 seconds. Otherwise it was fully powered off. That's about two minutes of use in total.
  • The power drain over the whole period was 90% - 57% = 33%
  • I'm going to assume the battery reading non-linearity has to do with statistics updating in the reading itself etc. it doesn't make sense otherwise. So I'm assuming linear power drain over the whole period from hereon after. Perhaps it's a mistake to make this assumption, and there is really something weird going on...mmm

Now, let's say the machine being powered on for battery level checking (the two minutes) accounts for 5% of the battery use. This is a very rough (over-)estimation, but OK. That means 33% - 5% = 28% is unaccounted for, that's more than a percent every three hours, or about 9 percent of powered-off drain per full day.

 

Not considering the weird readings, and assuming linear drain, this is still very, very much in my humble opinion. How can you explain a laptop battery drain for almost a tenth a day without anything using it? The only thing I can imagine using the battery in some way or another is a BIOS facility like wake on LAN (which is disabled) or 'always on USB' (disabled and nothing is connected). Am I missing something? This to me smells like: 1) a buggy BIOS, 2) a badly designed BIOS.

 

What's Lenovo's take on this? I see some tech experts answering in other support forum threads, do they have an opinion about this too?

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346 Posts

09-04-2019

United States of America

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  • Message 19 of 31

Re:P14s severe battery drain when powered off

2021-05-10, 2:24 AM

Have you tried going into the BIOS and disabling the battery and see if you have the same rate of loss?

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19 Posts

04-28-2021

Netherlands

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  • Message 20 of 31

Re:P14s severe battery drain when powered off

2021-05-10, 7:07 AM

Yes, I tried that a week ago (see one of my posts above). That was fine.

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