I was given this IBM ThinkPad i 1400 (2611 411) as part payment for a small job I did for someone.

I'd like to give it to my daughter to play around with in school and get into computers.

Although the battery shows 100% charged when I check its state, it doesn't run the laptop even for 5 seconds.

Is there something I can do with this pack?

And, how does one stop the machine from charging with the AC on if you want the battery to run down as a matter of course?

My minimal understanding is that it's no good to constantly top off the battery.

That battery is toast, you will have to replace it.
It is fine to run the machine on ac often. It is advised to run down a laptop battery completely every once in a while though. I try to run down my thinkpad at once or twice a month. I don't think I would run down the battery constantly. Both running on ac all the time and draining the battery all the time will wear it out faster. Just run it down every so often and other than that use it how ever you want.

<A HREF="http://www.folken.net/myrig.htm" target="_new">My precious...</A>

Thank you for that quick response. All that you've said sounds logical and I accept your advice.

When I get the new battery, what is the best way to integrate it with the laptop. There are no user guide manuals to help.

The battery should be very easy to replace. There will be some sort of realease switch and it should slide right out. Then just slide the new one in. The switch will probably have a symbol of a padlock both locked and unlocked.
I'd check for a battery on ebay, it will be A LOT cheaper.

<A HREF="http://www.folken.net/myrig.htm" target="_new">My precious...</A>

When you buy the battery, if you DO go the ebay route, make sure it is -NOT- a refurb, and make sure it is -NOT- used.

Trust me on this, I learned the hard way about used batteries