Battery life etc

[tim S]

Not wishing to re-hash an old subject, but I'm due for a new battery. My original T40 battery, now 3 years old, goes to about 45% then drops to the plug-in warning.

Any opinions about after market batteries vs. IBM originials?
Personally I favor IBM but any input into the less expensive generics is welcome.

I've only used my laptop about a dozen times on battery power in the 3 years I've owned it, and then only two or three times to full discharge, so I'm guessing that leaving the battery installed, as I do, is not the thing to do. Starting with the next battery I get, I'll leave it out, until I need it then see if it lasts any longer.
Tim S

[EOMtp]

What you describe is characteristic of the way Li-Ion batteries begin to fail.

Three points:
1) Buying batteries is like buying salt: NaCl is NaCl and Li-Ion is Li-Ion. Further, there are only a handful of Li-Ion cell manufacturers in the world. Everybody who "makes" batteries packages the "same" (Sanyo, Sony, Panasonic, etc.) cells in whatever form factor is required for their application. Just match the battery's physical size and voltage and select the one with the highest capacity, i.e., Amp-hours (Ah).

2) I don't know if the T40 has circuitry to turn off charging once the battery is full, as all newer units have. On modern Thinkpads, taking the battery out to "protect" it is unneccessary IF the charge cutoff circuitry is working properly.

3) Li-Ion batteries have limited shelf life. They deteriorate even if not used, just stored. Here is more information:
http://www.batteryuniversity.com/

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[dsigma6]

even though it may be toast regardless, did you try letting it drain the battery while in bios until it shuts itself off- then restart plugged in, and keep it powered on until it fully charges.

[tim S]

Hi Dsigma6.
Not sure what you mean by drain in BIOS. Do I turn on the laptop, hit F1 and leave it there until its fully drained? Is there a difference between draining a battery in BIOS and draining a battery in Windows? In any event once the laptop shuts off, should I let it fully charge in Windows, or in BIOS?
Thanks for the replies (EOMtp)
Tim S

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[bill bolton]

Buying batteries is like buying salt

In the case of assembled battery packs with on board micro-controllers, the practical experience is that its more complicated than that.

A search of the reports here on buying third party battery packs for T4x ThinkPads shows significantly more mixed results than for buying IBM branded battery packs.

Cheers,

Bill

[dsigma6]

Hi Dsigma6.
Not sure what you mean by drain in BIOS. Do I turn on the laptop, hit F1 and leave it there until its fully drained? Is there a difference between draining a battery in BIOS and draining a battery in Windows? In any event once the laptop shuts off, should I let it fully charge in Windows, or in BIOS?
Thanks for the replies (EOMtp)
Tim S

yes let it drain in bios by hitting f1. you can let it drain most of the way in windows though first, so you dont have to wait a year for bios to drain it. its ok for bios to shutdown out of nowhere, not good for windows. plug in after drain and start normally in windows. let it run, make sure standby/hib is off. screen can be closed of course. sorry if i typed silly im using keys that are 1/3" LxW.