61Wh battery becomes 55Wh battery after 140(?) cycles, voltage drop 0.2V

[Charlie_6]

I suspect that this battery has planned obsolescence. During the first half of the year of usage, the battery was at 100~101% health. Near one year usage the battery health suddenly went to 91%(may occasionally float to 95%).

System: AMD 7840U, with 61Wh battery (limited charging voltage 17.8V)
No BIOS update was done, the BIOS stays at 3.05
Arch Linux(6.13.6-arch1-1)

61Wh and 55Wh photos from official marketplace

However, notice the “Desired Voltage” half a year ago.

Desired voltage 17800 mV

$ sudo ectool battery
Battery 0 info:
  OEM name:               NVT
  Model number:           FRANGWAT01
  Chemistry   :           LION
  Serial number:          0035
  Design capacity:        3915 mAh
  Last full charge:       3755 mAh
  Design output voltage   15480 mV
  Cycle count             48
  Present voltage         16542 mV
  Present current         3630 mA
  Remaining capacity      620 mAh
  Desired voltage         17800 mV
  Desired current         3915 mA
  Flags                   0x0b AC_PRESENT BATT_PRESENT CHARGING

And here’s now

Desired voltage 17600 mV

$ sudo ectool battery
Battery 0 info:
  OEM name:               NVT
  Model number:           FRANGWAT01
  Chemistry   :           LION
  Serial number:          0035
  Design capacity:        3915 mAh
  Last full charge:       3558 mAh
  Design output voltage   15480 mV
  Cycle count             145
  Present voltage         17416 mV
  Present current         2450 mA
  Remaining capacity      2562 mAh
  Desired voltage         17600 mV
  Desired current         2740 mA
  Flags                   0x0b AC_PRESENT BATT_PRESENT CHARGING

(ignore the 3915mA to 2740mA, the current reduces when charging past 4.15V/cell since the very beginning, i.e MCC-CV charging)

Since now the battery health is 91% and 55/61=0.9, I can safely assume that the battery has 0 wear. The 9% wear is due to the voltage being ARTIFICIALLY reduced from 17.8V to 17.6V

Any explanation of that? I appreciate that the battery is available and can be replaced easily, but blocking the original voltage and creates the illusion of battery degradation is, well, unethical and unsustainable.

[Charlie_6]

@MJ1

It’s 61Wh when you need it.

No more after a year, despite 0% wear

@Second_Coming

Back to a 55Wh-ish battery.

Exactly. But not because of the BIOS, but the battery management. It would by very difficult if not impossible, for an average joe to hack the BMS and get the full capacity back.

Hacking the BMS of a laptop is so niche that very few people know that it exists. Combined with less Framework users compared to other popular brands, which means remedying this problem is a nigh-impossible task. The battery is also not standardized, currently there’s no third-party manufacturer of the battery, unlike other brands like Lenovo, ASUS or System76.

@Second_Coming

Exactly. No difference in my book if you had to do a 61Wh - 10% just so it has the same level of aging reliability (as the 55Wh battery) in the long-plugged-in use case.

The 61Wh is over promised in this case of long-plugged-in.

It’s almost like a hardware regression via software (BIOS).

Found out that the 61Wh battery just means you pay more for a premium to unlock more capacity, said premium will expire after roughly a year(may be different, your mile may vary).

[Zoe]

battery life is unpredicitable and highly variable. If you feel like your battery has worn beyond what is expected contact support.

Update to the latest bios, I belive that should be 3.07, their exist some improvments to the battery managment, aimed at improving battery life/health.

/Zoe

[Tom1]

@Zoe

Update to the latest bios, I belive that should be 3.07,

Hah, no. Definitely don’t do that. 3.07 is in beta and it has a bug that is causing the battery limiter to stop working. You can see the wall of bug reports about the limiter in the bios beta thread.

[Charlie_6]

@Tom1

3.07 is in beta and it has a bug that is causing the battery limiter to stop working

A stopped working limiter is akin to a turned off limiter. So the max voltage should be the same on both 3.05 and 3.07 with battery extender off and charge limit 100%

[Tom1]

Yeah it’ll be the same, but you won’t be able to turn that limiter back “on” and you won’t be able to downgrade back to 3.05. I assume as someone who is so concerned about your battery health that you’re not normally running this without the charge limiter enabled?

[Charlie_6]

I enable the charge limiter to 75%, I only set to 100% when doing a cycle to calibrate the battery gauge, or read the (more accurate) battery health.

[James_Jarrett]

@Charlie_6

Since now the battery health is 91% and 55/61=0.9, I can safely assume that the battery has 0 wear. The 9% wear is due to the voltage being ARTIFICIALLY reduced from 17.8V to 17.6V

Any explanation of that? I appreciate that the battery is available and can be replaced easily, but blocking the original voltage and creates the illusion of battery degradation is, well, unethical and unsustainable.

55/61 is 90.16%
Your 91% to 95% is higher… you’d expect a gradual reduction in capacity over time that would pass through 90% on the way down.

You can not safely make the assumption that a battery that’s been used for a year has 0 wear. That would be impossible. Batteries degrade even sitting on a shelf.

Furthermore, I think you’re misreading your ectool output. “Desired voltage”, if you look at the ectool code, is described as the desired charging voltage, which would be higher than the voltage produced by the battery while discharging.

15480 mV, Design output voltage, is probably the number you’re thinking of, in your ectool output. If the battery is asking for 17.6 volts instead of 17.8 volts to charge, that’s just a gentler charge.

[Charlie_6]

Why the battery is asking only 17600mV when it asked 17800mV last year?(and the Limited Charging Voltage is 17.8V). I also found the 55Wh battery asking 17400mV instead of 17600mV after being used for a while

[James_Jarrett]

It’d probably be better for an engineer to answer since my entire expertise is hazy notions I got from watching videos about cell phones or skimming explanatory web pages about battery chargers.

From what I think I understand about battery charging, 17.6 V is still a high enough voltage to get the battery full, since its operating voltage at a full charge is only 15.48 V. Because current = voltage / resistance, the lower voltage will just result in a slower current, charging the battery to full more slowly.

Doing it slower would generate less heat, and generally be easier on the battery. Maybe the reduced voltage target came from a BIOS update, as part of the fix for those issues with the 61 Wh batteries, or maybe it’s normal over the lifetime of the battery based on some model of their internal chemical degradation over time.

Something like that would be my guess.

[Charlie_6]

I replied here to prevent off-topic

@pkunk

I can see the appeal to believing there is a planned obsolescence from the battery manufacturer. However, I have a hard time believing this is the case from the standpoint of the charging and battery management is done through the charge controller which is independent of the battery itself.

The battery is somewhat inexpensive by comparison to other laptop vendors. Plus, it is literally designed to be repaired if it wears out or is defective.

If someone honestly believes their laptop battery is degraded they should start a case with support and let them determine if it should be replaced under warranty. Otherwise, it is a wear component similar to cell phone batteries. The big difference is its ease of replacement.

I praise the design of the laptop for easy battery replacement and inexpensive batteries. However if the 0.2V charging voltage is confirmed to be very common(not just my case), I’ll criticize the (relatively minor, almost unnoticeable) planned obsolescence from the battery manufacturer at the same time.

Here are other cases

@njsf

[24097.723428 charge_request(17600mV, 0mA)]
[24098.407295 Battery 100% (Display 100.0 %) / 7h:53 to empty, not accepting current]

Then his battery

@njsf

[600917.245477 charge_request(17400mV, 3572mA)]

Here’s my case in April 2024

@Charlie_6

$ sudo ectool battery
Battery 0 info:
  OEM name:               NVT
  Model number:           FRANGWAT01
  Chemistry   :           LION
  Serial number:          0035
  Design capacity:        3915 mAh
  Last full charge:       4047 mAh
  Design output voltage   15480 mV
  Cycle count             29
  Present voltage         16148 mV
  Present current         -285 mA
  Remaining capacity      2759 mAh
  Desired voltage         17800 mV
  Desired current         3915 mA
  Flags                   0x06 BATT_PRESENT DISCHARGING

This was the same battery (I only have one 61Wh), note the cycle count 29 and desired voltage 17800

[James_Jarrett]

That’s what you would expect though. As your battery degrades, you want to charge it slower over time.

Here, this is a paper I found about EVs, just searching around randomly: Lithium-ion battery aging mechanisms and life model under different charging stresses - ScienceDirect

From the abstract,

It is indicated that charging current and cut-off voltage should be reduced to retard battery degradation when the battery degrades to a certain extent. The time when the loss of electrode material accelerates is taken as the crisis to reduce charging current and the time when the loss of lithium inventory accelerates is taken as the crisis to reduce charging cut-off voltage.

Lower charging voltage will cause the charging current to be lower, which will charge the battery slower, while physically / chemically breaking it down less.

So the battery engineers have models so that when they’ve got some indication that the battery’s x% degraded, they lower the charging voltage, to maximize its life as much as they can. That’s what you’re seeing. If the BMS kept trying to charge your battery at the same voltage level as when it was new, the battery would just degrade faster and die sooner. Lower charging voltage == more cycles out of your battery.

[Charlie_6]

@James_Jarrett

Here, this is a paper I found about EVs, just searching around randomly: Lithium-ion battery aging mechanisms and life model under different charging stresses - ScienceDirect

Tesla used this as an excuse to cause up to 20% of artificial degradation, multiple, times.

@James_Jarrett

It’d probably be better for an engineer to answer since my entire expertise is hazy notions I got from watching videos about cell phones or skimming explanatory web pages about battery chargers.

I worked as an electrical engineer a while ago and part of my work was with battery. I measured the voltage-capacity curves similar to this one for a variety of make and models under different voltage and temperature. My company has a 5kW electronic load, more than enough to test most batteries for portable devices.

My working experiences with batteries is the reason I discovered the sudden capacity drop caused by the artificial 0.2V voltage downgrade.
In April 2024 I posted my measurement of discharge curve

measurement

@Charlie_6

%, remaining capacity, open-circuit voltage
91%, 3618mAh, 17312mV
80%, 3180mAh, 16742mV
70%, 2782mAh, 16310mV
60%, 2387mAh, 15876mV
50%, 1988mAh, 15518mV
40%, 1589mAh, 15283mV
30%, 1194mAh, 15134mV
20%, 795mAh, 14959mV
30%, 1194mAh, 15209mV
40%, 1589mAh, 15396mV
50%, 1986mAh, 15640mV
60%, 2384mAh, 16011mV
70%, 2783mAh, 16460mV
80%, 3178mAh, 16838mV
91%, 3618mAh, 17331mV
100%, 3972mAh, 17784mV

The 61Wh battery, when charged to 17.6V, is only 91% full. Note the 100%, 17784mV. Due to internal resistance, the voltage drops slightly after charging, in this case, a 16mV drop.

@James_Jarrett

Lower charging voltage will cause the charging current to be lower, which will charge the battery slower, while physically / chemically breaking it down less.

We already have that, it’s “Battery charge limit” in the BIOS settings. Typically, the battery is charged to 16V(4V/cell, 60% setting), to 16.8V(4.2V/cell, 80% setting), when plugged in. Only charge to 17.8V(4.45V/cell, 100% setting) when you absolutely need it.
I set it to 75% in BIOS most of the time for the whole year, only charged to 100%/17.8V in less than 5 times. as a result, the battery degradation is very small, 33mAh, 0.84%, less than 1 percent a year.
My battery’s actual health is 99% or more precisely, 99.16%, but why I only got 91% health on the reading? This is because the battery only charges to 17.6V instead of 17.8V, The battery is only 92% full, 1-(1-0.99)-(1-0.92)=0.91

@James_Jarrett

So the battery engineers have models so that when they’ve got some indication that the battery’s x% degraded, they lower the charging voltage, to maximize its life as much as they can. That’s what you’re seeing.

I, as a battery engineer, maximize my battery life as much as I since from the very beginning, limiting the charge of my battery to 75%(4.15V/cell) and I only charged it to 100% in less than 5 times in a year.
As a battery engineer, I also know that if you lower the charging voltage for 0.2V in a 4-cell battery, the battery will only be charged to 92% full. If the user(or the computer) doesn’t know it, they will believe that the battery has 8% degradation, in my case, 1% actual degradation, 8% artificial degradation caused by BMS misbehaving, 9% displayed degradation. That’s what you’re seeing.

[James_Jarrett]

Sorry if I bothered you. Maybe I misunderstood the “Desired Voltage” term. My copy of ectool doesn’t display it. I still think you’ve probably got causality backwards though.

Actually, watching ectool as my laptop charges and discharges, I misunderstood Design output voltage too, thinking it was the ceiling, not the average or so.