Thinkpads Forum

Why are the batteries for the X60s and X61s different?

In the power manager under "battery information" my X60s says the FRU part number is 42T5249 while the X61s says the FRU part number is 93P5030.

Why would the FRU part numbers be different? Shouldn't they take the same replacement battery?

Additionally, My X60s battery (Sanyo) holds a full capacity charge of 80.34 Wh despite the design capacity being only 74.88 Wh. That is a significant difference! My X61s battery (Sony) holds a full capacity charge of exactly 74.88 Wh (same as design capacity).

There are frequently multiple battery FRUs that are interchangeable. The HMM lists the following 8-cell batteries:

Sanyo 92P1171
Sony 92P1173

and

Sanyo 93P5029
Sanyo 42T4506
Sanyo 40Y7904
Sony 93P5030

I didn't find a 42T5249 listed, though.

how long can the battery life last for these 2 different models?

Apart from potential battery explosions the Li-ion batteries really have very similar characteristics and their life is primarily determined by your usage patterns.

So what does that mean? Well, my trusty X31 has 29.37 Wh of remaining capacity out of the original 47.52 Wh. Not stellar, but at 62% of original, it's by no means dead yet. And that's after two and a half years 825 charge cycles, so you can indeed get a lot out of a Li-ion battery!

You should try performing a battery reset in your power manager, the readings are definitely off.

Why do you think the readings are off? And in what way?

I meant that it being "off" in a sense that the current listed full capacity charge being higher than the design capacity.

I encountered that problem initially too. It had gone from a value same as the design capacity, to a value higher (which I then performed a reset).

The battery had actually lost capacity at that point of time, but something was wrong with the estimation of power manager, so the values went off, higher than the designed value.

Nothing much to worry about that though.

Yes, the "full charge capacity" is an estimate and can drift ... though in my case it's well down by now.

Comage wrote:I meant that it being "off" in a sense that the current listed full capacity charge being higher than the design capacity.

I encountered that problem initially too. It had gone from a value same as the design capacity, to a value higher (which I then performed a reset).

The battery had actually lost capacity at that point of time, but something was wrong with the estimation of power manager, so the values went off, higher than the designed value.

Nothing much to worry about that though.

The battery I have for my X60s with the full capacity higher than the design capacity is brand new - only 6 charge cycles - and it has been like this from new.

Do you really think it needs a reset? Isn't it possible for a battery to have a higher full capacity than its design capacity?

Well it won't result in any performance issues, so you can leave it there if you wish too.

Sometimes batteries stay in warehouses for quite some time before they are shipped out to customers, so that might account for the difference.

However, I would check to make sure that the battery drains "linearly" (i.e. there is no jump from like 70% to 60% under a constant power load). If there is, it means the li-ion crystals have crystalised (memory effect).

I had one Sanyo exchanged within the first year because it exhibited this problem.