Is it best to REMOVE battery if one is going to leave TP plu

[nikemen]

I tried a search for this, didn't find anything relevant.

If I am going to leave my TP plugged into a dock for a while, weeks, or plugged into the wall a while, days, is it best to charge the battery and remove it? Or, just leave it plugged in?

Tell me what you are prone to do and if you have any experience with it affecting battery performance down the line.

[Kenn]

Technically, if you're leaving it for more than a week or so, battery out and at about 50% charge is best.

If general you're going to be plugged in for a while, taking the battery out helps because the heat of the laptop being on (especially while in the dock) works against the battery's permanent life, albeit at a very slow rate.

[Leon]

then again, you're taking off your free UPS.....

[Kenn]

then again, you're taking off your free UPS.....

True. I generally don't recommend it while working on AC in a public area (people always trip over the cord), but if it's docked at home, only power outages need to be considered, not that they're trivial of course.

[beeblebrox]

-nikemen:

PLEASE TAKE NOTICE THAT REMOVING THE BATTERY CAN FATALLY DAMAGE YOUR THINKPAD!!

Actually you are playing Russian Roulette by not using the battery pack, if you are out of warranty.

I saw a T21 dying on it, and we have a bunch of T20-T22 with dead battery and thus a CRC 0175 error as well.
BTW: IBM does not advise to using notebooks without battery pack, for good reason.
The problem is the Atmel EEPROM, which stores CRC and supervisory passwords. That chip is accessed a few thousand times during boot-up. If you potentially step on the power cord during POST, your Thinkpad in 95% of cases is toast.
You also get the same fatal error in rare cases when you are offline and your battery runs down to about 2% and you forgot to turn off the notebook. When you turn on again, the Thinkpad might find the voltage to low and tell you a low battery error. OR it might boot and break down 2 seconds later -> CRC error, fatal !

I had this, and you can google for thousands of posts for CRC 0175 errors on thinkpads.
The engineer jerks at IBM (I am an engineer myself and know that stuff a bit) did not intend to use a rescue default setup in case the EEPROM is corrupted. They are using the very same Atmel chip configuration throughout the entire more modern Thinkpad line.

Looking at a heap of about 20 dead Thinkpads with the same CRC problem, I can only recommend to buy an old battery for cheap, that does hold a supply of 20 minutes, to be on the safe side, and save your valuable new battery at 40% charge in a sealed plastic box in the fridge.
In this configuration the battery deteriorates very slowly.

BTW: To learn a bit about the new IBM policy, just be reminded that IBM changed the BIOS on most Thinkpads so that an IBM-compatible battery won't work anymore. You would have to buy an original IBM battery for their stratospheric price tag. So better use an old one as a kind of USV.

[Roisin]

so how do you fix that CRC 0175

and how much does it cost if you are out of warranty?

[K. Eng]

beeblebrox,

How exactly does the EEPROM get corrupted from just interupted reads? Are you sure this problem occurs in modern ThinkPads?

If this is true, it is worrisome, but I've never heard of this happening before.

[Kenn]

Also, I've looked up some web pages, and even in the T20 days they say the problem is exhibited by "some earlier thinkpads."

Interrupted power is never good, but EEPROMs are usually pretty sturdy, and I can't believe they're being written to during every boot, since they have limited write-to cycles (usually a hundred or so reflashes), right?

I'd be very surprised if this kind of behavior happened on T4x series.

[K. Eng]

Kenn, from my limited understanding of EEPROMs, they generally can be written a few thousand times before expiring. However, they have practically infinite read cycles.

I seriously doubt the EEPROM is being written to every time the ThinkPad is turned on. I think that some setting and firmware changes might necessitate a read, but that's just about it.