Battery questions: 80% charge and battery condition

[Rotavator]

I got a new laptop battery for my Dell XPS 17 L701X, a machine built in 2010. I am running LM 20.2 Cinnamon. The battery powers the laptop for about 2 hours, under what I would consider light normal use (no gaming, no streaming, but some reading or shopping on the web). I am trying to ascertain if this is normal, and how good this new battery is. I noticed this in the system information screen (with charger plugged in and battery monitor icon in lower right corner of desktop showing 100% charged):

Code: Select all

Battery:   ID-1: BAT0 charge: 59.6 Wh condition: 59.6/73.3 Wh (81%) volts: 12.3/11.1 
           model: SIMPLO Dell serial: <filter> status: Full 

Is the battery charged to 100% of its physical capacity, or does LM limit it to 80% with some charge management software?

Also, the original Dell battery was labelled for 90 Wh, the replacement was advertised as 7800 mAh, which at 11.1 volts would be 86.6 Wh. If I am interpreting the info above correctly, it is telling me that my battery actually has a maximum capacity of only 73.3 Wh, or about 85% of what was advertised. Is that right? Is this grounds to request a partial refund or replacement from the battery vendor?

Thanks!

[kato181]

Your system is 12yrs old and running LM 20.1 Cinnamon will drain your resources, I would switch to LM 19.3 XFCE, it has low resource requirements.

[Rotavator]

I am not complaining about the 2-hour battery life, I'm just wondering if the system manages the battery to only 80% of full, and if the figures listed in the system report are reliable, and if I am interpreting them correctly. Good to know I could choose a less resource intensive version of LM if that really becomes an issue. I'm not planning to go off grid much, but one never knows!

[kato181]

You could try draining the battery completely, then remove the the battery, then turn the laptop on to drain the excess power residual in the capacitor, then replace the battery and charge again without the laptop on so you can get a full charge if that is possible.
Laptop manufacturers don't guarantee a full 100% charge as some have different ratings. You can check the manufacturers specs on them. But using a cinnamon desktop will use battery power a lot quicker. LM doesn't limit the charge of a battery, charging will be limited whilst the laptop is in use.

[smurphos]

Is the battery charged to 100% of its physical capacity, or does LM limit it to 80% with some charge management software?

No it just means the battery will not charge to it's rated out off the box capacity. Li-On / Li-Poly batteries have a limited lifespan, in terms of charge/uncharge cycles - and running them always plugged is also not great for longevity.

E.g I'm using the original Dell OEM battery that came with my laptop which is about 2 and half years old now. It's mostly on AC power, but the machines BIOS/UEFI does have an option to manage the battery for 'mostly AC use' which I have checked.

My '100%' is now '76.8%' of the rated capacity.

I take it it's not a new OEM battery, but a third-party manufacturer? They are often crap. On another older laptop I was replacing the battery every year - unfortunately no OEM batteries were available but all the generic third-party manufactured ones I tried were crap, and would deteriorate rapidly.

[Rotavator]

Thanks, @Smurphos. Yes, it's a generic battery, not OEM. I suppose you could say I primarily use it as a UPS. My old battery was the original that came with the machine back in 2010! It was down to providing about 1 - 2 minutes of standby power.

I checked my BIOS settings and the only related one is called "charger behavior", enabled or disabled. Disabled means the charger won't charge the battery, it will just power the laptop.

I see a couple of programs running in LM that monitor the battery, but they don't have any options such as "limit charge to the 20% - 80% range", which is a common power management recommendation. Because that's a common recommendation, I thought maybe something on my machine is implementing it. The monitoring programs are called Power Management and Power Statistics. The latter shows me that "energy when full" is 57.9 Wh, while "energy (design)" is 73.3 Wh. Do you think that a new OEM battery would show "energy when full" equal to (or almost equal to) "energy (design)"?

I am still puzzled as to whether you get the most life out of the battery by using it constantly, but keeping it in that 20-80% range, or by not using it (and in this case, since it is at 80% at most anyway ... or is it 100%? ... I don't know. I'll probably have the charger plugged in most of the time because I mostly use this at home in the same location. I guess if I charged it to 80% of the charge it will take, and then go into my BIOS settings and disable the charger, then the battery would effectively be "in storage", yet it would be available as a UPS if our power went out. Pretty clunky having to go into the BIOS though ...

[kato181]

All batteries for laptops etc have a memory, that's why if you read the batteries manufacturers conditions it will suggest that you fully drain the battery and then recharge for a full12-18hrs before using the computer. That's what I do once every 2 months.

[cliffcoggin]

All batteries for laptops etc have a memory, that's why if you read the batteries manufacturers conditions it will suggest that you fully drain the battery and then recharge for a full12-18hrs before using the computer. That's what I do once every 2 months.

That was true only of nicad batteries which had a memory effect. If the laptop has a modern lithium battery then fully discharging it will damage it.

[kato181]

So I just read...You learn something new each day....