Final
comment and
revelation re using laptops with "old" batteries.
The thing that caused my daughter to come to me with her "use laptop with bad battery question", was that she was continually getting a variety of error messages. Lo and behold, with the bad battery removed, the errors ceased and the computer's operation is absolutely fine.
It seems the defective battery had reached the point where it was pulling down (shorting) the operating voltage to a point where the motherboard/cpu were throwing a variety of indicated errors.
Moral of the story, if you have a bad battery in a laptop, and you are not about to replace it promptly, take it completely out and operate the laptop only with the charger.