Battery life on T420

[Peter Istria]

I've just acquired a t420 with 8/500. It had Windows 10 on it and I've replaced it with Linux mint. Batter life seems little more than an hour.
any thoughts please before I get a new battery?
Kindest regards
Peter

[theterminator93]

I can't say exactly how on Linux, but there should be a way to check the Watt-hour capacity and discharge rate of the battery. 6 cell or 9 cell?

You should be seeing 3-5 hours on a 6 cell and 4-7 hours on a 9 cell, for light-moderate use.

[atagunov]

Hallo, TLP highly recommended. It's kind of a shame that with Windows you get everything almost immediately and with Linux you need to know what to install TLP is the bit of software that limits power consumption when on battery. Once installed you can mess with /etc/tlp.conf a bit. I for example use

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CPU_MAX_PERF_ON_BAT=60

on my X220 which should be pretty similar to your T420. I've been getting >3 up to 4 hours watching Youtube videos and browsing on my X220 with a new KingSener (AliExpress) 6-cell battery.

While at that you can set START_CHARGE_THRESH_BAT0=.. to some value that makes sense to you.

Sadly I had to stop using STOP_CHARGE_THRESH_BAT0=.. setting. I tried to set it to 80 or 90 to prolong batter life. However on my X220 it resulted in the documented case of erratic behaviour. For it me it meant that battery indicator went down to around 45% normally (or was it 35-40? don't remember) and then it would plummet super-quick to under 5% and then X220 would switch off soon. Had it both with genuine and KingSener batteries. So I removed the upper limit..

I'm the lazy one who runs Ubuntu btw if it matters. For me the commands were (note those extra packages that help TLP work better)

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sudo add-apt-repository ppa:linrunner/tlp
apt-get install tlp tp-smapi-dkms acpi-call-dkms smartmontools linux-tools-generic powertop

Actually I think if you just install TLP and run

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sudo tlp-stat -b

it may tell you which packages it's missing to provide full functionality. And I love this tlp-stat command So useful! I also love

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tlp recalibrate BAT0

That's something for Windows users to be envious of here They only can do it via BIOS we, Linux people, can recalibrate our batts from command line

Powetop is an odd one on that apt-get install list. It's unrelated to TLP. Powertop is a useful utility from Intel I think. It's great to tell you how many Wt you're consuming when running on batt. Try it! But don't allow it make advices to you I think it's got some autotune mode.. For a while I was confused since this autotune seems similar to what TLP does. My takeaway is to use powertop as diagnostics/monitoring utility but rely on TLP to actually manage power for you

[theterminator93]

And I love this tlp-stat command So useful! I also love

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tlp recalibrate BAT0

That's something for Windows users to be envious of here They only can do it via BIOS we, Linux people, can recalibrate our batts from command line

Actually, recalibrating can be done in Lenovo Power Manager and Lenovo Vantage. I have never seen an option to recalibrate a ThinkPad battery from BIOS.

[riffer]

If you can throw windows on a spare drive and run Lenovo Diagnostics to see what's up with the battery.

[atagunov]

If you can throw windows on a spare drive and run Lenovo Diagnostics to see what's up with the battery.

Definitely a possibility. However please also appreciate what tlp-stat, part of TLP package can show on my T520:

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...@...:~$ sudo tlp-stat -b
[sudo] password for ...: 
--- TLP 1.3.1 --------------------------------------------

+++ Battery Features: Charge Thresholds and Recalibrate
natacpi    = active (thresholds)
tpacpi-bat = active (recalibrate)
tp-smapi   = readonly (data)

+++ ThinkPad Battery Status: BAT0 (Main / Internal)
/sys/devices/platform/smapi/BAT0/manufacturer               = LGC
/sys/devices/platform/smapi/BAT0/model                      = 42T4969
/sys/devices/platform/smapi/BAT0/manufacture_date           = 2011-12-13
/sys/devices/platform/smapi/BAT0/first_use_date             = 2012-07-11
/sys/devices/platform/smapi/BAT0/cycle_count                =     32
/sys/devices/platform/smapi/BAT0/temperature                =     37 [°C]
/sys/devices/platform/smapi/BAT0/design_capacity            =  86580 [mWh]
/sys/devices/platform/smapi/BAT0/last_full_capacity         =  73740 [mWh]
/sys/devices/platform/smapi/BAT0/remaining_capacity         =  35780 [mWh]
/sys/devices/platform/smapi/BAT0/remaining_percent          =     49 [%]
/sys/devices/platform/smapi/BAT0/remaining_running_time_now = not_discharging [min]
/sys/devices/platform/smapi/BAT0/remaining_charging_time    = not_charging [min]
/sys/devices/platform/smapi/BAT0/power_now                  =      0 [mW]
/sys/devices/platform/smapi/BAT0/power_avg                  =      0 [mW]
/sys/devices/platform/smapi/BAT0/state                      = idle

/sys/class/power_supply/BAT0/charge_start_threshold         =     40 [%]
/sys/class/power_supply/BAT0/charge_stop_threshold          =     50 [%]
tpacpi-bat.BAT0.forceDischarge                              =      0

Charge                                                      =   48.5 [%]
Capacity                                                    =   85.2 [%]

Not bad, is it? Note, I was on AC power when running this so the batt is not discharging. Also I have

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START_CHARGE_THRESH_BAT0=40

in my /etc/tlp.conf so it's not charging either. It's idle. Also as I mentioned earlier this nice small utility

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sudo powertop

when notebook runs on battery power shows you the current drain in mWt; perhaps the windows utility can do this as well, but to me it's a small miracle. I can see how power usage changes between idle state and watching a youtube video, etc. I am a bit sad it can't show the same when on AC power but alas..

[riffer]

If you can throw windows on a spare drive and run Lenovo Diagnostics to see what's up with the battery.

Definitely a possibility. However please also appreciate what tlp-stat, part of TLP package can show on my T520:

...

Lol! I completely forgot about that. I was running Zorin Lite for a while and had that installed. I should check to see if my current UbuntuDDE install has it.

P.S. My daily driver is a desktop with Elementary/Windows 10 dual boot so my T420 is often the guinea pig for new distros.

[heartiron3000]

Hi, thanks so much for giving info on battery maintenance tools on Linux. I have been a bit lost.
I purchased a battery for my T420 a few years ago specs as follows:

Battery type: Li-ion; Capacity: 6600mAh; Cells: 9-cell; Voltage: 11.1V ( Compatible with 10.8V )
Expected operation time: Around 2.5-3.5 hours. The actual operation time will depend on how much electricity is required by the device and how you use it
Over-charge and discharge, over-voltage, short Circuit Protection, CE/FCC/RoHS Certified for safety

Thiis is my laptop. On this battery, it doesn't work unplugged.
But I get confusing readings for it from the default Gnome battery read (I am on Debian), and I wonder if there are some tweaks I can do to make it work better.

When I run TLP I get this reading, can you help me figure out what it means. Is there something I can do to make it work better?

I run this:

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sudo tlp-stats -b

I get this:

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root@debian:/home/killamanjiro# tlp-stat -b
--- TLP 0.9 --------------------------------------------

+++ ThinkPad Extended Battery Functions
tp-smapi   = active
tpacpi-bat = active

+++ ThinkPad Battery Status: BAT0 (Main / Internal)
/sys/devices/platform/smapi/BAT0/manufacturer               = SANYO
/sys/devices/platform/smapi/BAT0/model                      = 42T4763
/sys/devices/platform/smapi/BAT0/manufacture_date           = 2016-10-24
/sys/devices/platform/smapi/BAT0/first_use_date             = 1980-07-19
/sys/devices/platform/smapi/BAT0/cycle_count                =     81
/sys/devices/platform/smapi/BAT0/design_capacity            =  66000 [mWh]
/sys/devices/platform/smapi/BAT0/last_full_capacity         =  53280 [mWh]
/sys/devices/platform/smapi/BAT0/remaining_capacity         =   6070 [mWh]
/sys/devices/platform/smapi/BAT0/remaining_percent          =     11 [%]
/sys/devices/platform/smapi/BAT0/remaining_running_time_now = not_discharging [min]
/sys/devices/platform/smapi/BAT0/remaining_charging_time    =   1011 [min]
/sys/devices/platform/smapi/BAT0/power_now                  =   2306 [mW]
/sys/devices/platform/smapi/BAT0/power_avg                  =   2306 [mW]
/sys/devices/platform/smapi/BAT0/state                      = charging

tpacpi-bat.BAT0.startThreshold                              =     96 [%]
tpacpi-bat.BAT0.stopThreshold                               =    100 [%]
tpacpi-bat.BAT0.forceDischarge                              =      0

Charge                                                      =   11.4 [%]
Capacity                                                    =   80.7 [%]

[atagunov]

Battery type: Li-ion; Capacity: 6600mAh; Cells: 9-cell; Voltage: 11.1V ( Compatible with 10.8V )
Expected operation time: Around 2.5-3.5 hours. The actual operation time will depend on how much electricity is required by the device and how you use it
Over-charge and discharge, over-voltage, short Circuit Protection, CE/FCC/RoHS Certified for safety

Just being curious: does it look original? Or an aftermarket one? 2.5-3.5hrs looks a bit too low for a 9-cell

Thiis is my laptop. On this battery, it doesn't work unplugged

I'd say this is the main bit. If you can't make it run on this battery no matter what you do it looks like the battery is not fit for purpose I'm a bit of a fan now of KingSener batteries on AliExpress. They cost £25-30 delivered here in the UK and take less than a month to arrive, even now in times of Covid. I've only used one in anger and it is all-rightish. Haven't seen big issues with it. It's a 6-cell and I'm getting 3 - closer to 4 hours with X220, which shouldn't be that different from your T420. I'd say you may be in for this kind of money! Others will probably advise to get an original batt in a good shape. I've got less experience here, so I will not speak further

But I get confusing readings for it from the default Gnome battery read (I am on Debian), and I wonder if there are some tweaks I can do to make it work better.

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root@debian:/home/killamanjiro# tlp-stat -b
--- TLP 0.9 --------------------------------------------

+++ ThinkPad Extended Battery Functions
tp-smapi   = active
tpacpi-bat = active

+++ ThinkPad Battery Status: BAT0 (Main / Internal)
/sys/devices/platform/smapi/BAT0/manufacturer               = SANYO
/sys/devices/platform/smapi/BAT0/model                      = 42T4763
/sys/devices/platform/smapi/BAT0/manufacture_date           = 2016-10-24
/sys/devices/platform/smapi/BAT0/first_use_date             = 1980-07-19
/sys/devices/platform/smapi/BAT0/cycle_count                =     81
/sys/devices/platform/smapi/BAT0/design_capacity            =  66000 [mWh]
/sys/devices/platform/smapi/BAT0/last_full_capacity         =  53280 [mWh]
/sys/devices/platform/smapi/BAT0/remaining_capacity         =   6070 [mWh]
/sys/devices/platform/smapi/BAT0/remaining_percent          =     11 [%]
/sys/devices/platform/smapi/BAT0/remaining_running_time_now = not_discharging [min]
/sys/devices/platform/smapi/BAT0/remaining_charging_time    =   1011 [min]
/sys/devices/platform/smapi/BAT0/power_now                  =   2306 [mW]
/sys/devices/platform/smapi/BAT0/power_avg                  =   2306 [mW]
/sys/devices/platform/smapi/BAT0/state                      = charging

tpacpi-bat.BAT0.startThreshold                              =     96 [%]
tpacpi-bat.BAT0.stopThreshold                               =    100 [%]
tpacpi-bat.BAT0.forceDischarge                              =      0

Charge                                                      =   11.4 [%]
Capacity                                                    =   80.7 [%]

"first_use_date" is dodgy here of course. On the battery I currently have plugged into this T520, presumably an original battery, first use date is after manufacturing date. They are 2012 and 2011 btw and the batt is still going strong!

I don't have enough experience to tell you what a bad "first_use_date" signifies. Dodgy knock-off? Original that has gone off the deep end? Re-celled/repaired? A diy-enthusiast played with SMBus commands?

Other readings in your print-out look normal, seems like a 66Wh battery that has been worn down to 53Wh, currently at 11% charge, charging. But that probably isn't worth much if you can't make it work. Replace it.

Update: it is of course possible that battery is okay but Thinkpad has got issues.. Or that both have issues %-)

[KentT]

My T420 which runs Linux Mint 20 Ulyana (CInnamon) gets 3 hours battery life, a 2.5 Ghz Core i5 with 4 GB RAM. It's temporarily down though, took a hard bounce from 6 feet when it's owner with Cerebral Palsy spasmed and took a tumble. Still boots, but palm rest got cracked. Otherwise OK, replacement palm rest ordered and on it's way. About one hour of my labor, it will be back together again and in use. A testimonial to older ThinkPad durability and ruggedness.