Full Charge Capacity vs Design Capacity

[rbsrao79]

Hi,
I've had my t60-2613-eau for about 2 months now. I've noticed in the Power Manager that

Full Charge capacity = 54.93
Design Capacity = 56.16

Thats about a 2% loss over 2 months ? Can this be considered normal. I'm not really impressed with the battery discharge time. It lasts about 2.5 hours even under power saving mode (low display, frequency scaling) etc.


Rajeev

[Badger]

See here:

http://forum.thinkpads.com/viewtopic.php?t=28617

How many cycles do you have on it? I was going to say that it's weird that it's your main battery, but if you're not using an UltraBay battery like the rest of us then it makes sense that your main battery is going to have a lot more cycles on it. It seems like the majority of people in that thread use the UltraBay (including myself), so it must take the brunt of the discharge hit.

It'd be really nice if IBM/Lenovo could do something to prevent the battery from discharging all the way. But then you wouldn't have to buy so many batteries from them.

[rbsrao79]

I've got 17 cycles on it. I don't use an ultra bay battery. This battery happens to be a sony, but unfortunately it wasn't part of the recall.

Rajeev

[Badger]

I've had my T60 2613-EAU for about two months, too. The main battery has 15 cycles on it, the UltraBay is at 39. The main battery still has its full capacity. The UltraBay, however, is at 22.43 out of 29.16 Wh. Both are Sony's.

I'm wondering if doing the "battery gauge reset" would help yours out?

[rbsrao79]

What exactly is one cycle ? Is it one full discharge and charge ?

Rajeev

[christopher_wolf]

What exactly is one cycle ? Is it one full discharge and charge ?

Rajeev

Pretty much; a recalibration cycle is also counted as a cycle.

It usually counts as a cycle once it gets below the warning threshold, 5% for me, and then recharges above the charge threshold, 96% for me, at least once afterwards.

[Kel Ghu]

Cycles aren't important... Time is.. And capacity and stuff are based on voltage % based on calibration, meaning it is kinda meaningless. Battery can lose voltage without losing capacity.

read this: http://en.wikipedia.org/wiki/Lithium_ion

Most ppl are still using batteries like if it was the old Ni-Cd battery.

[rbsrao79]

I guess, if my full charge capacity goes down in the next month further, I'll make a call to lenovo.

Rajeev

[Kel Ghu]

There's nothing they can do about it... it's the way it is. And why do you think batteries are only guaranteed a year?

You can do a reset, the shown capacity will raise but it won't change anything. Li-ion batteries' capacity decays with time, no matter if you use it or not.

[renhui]

Mine Sony battery only holds 90% of it's design capacity now after 5 month of use(105 cycles on it now).
At the same time, the Sanyo battery on the X41T can also only hold 90% of design capacity after a gentle 5 months use(60 cycles now).
I was just wondering under what circumstances would Lenovo/IBM actually replace the battery?

[rbsrao79]

Hi,
I understand it is inevitable, but I'm already down to some 2.3 hours on full charge. If it goes down further, then battery won't be of much use.

Current my power manager is set on optimize for battery lifespan. I'll perform a battery a reset and see how much that helps. It may not be a battery fault at all, but to do with the charging mechansms. because despite having the thresholds set, I see the battery in charging mode even after the threshold has been crossed.

Rajeev