1991 Mercury Topaz car died and the battery appeared to be dead.

You may or may not be having a problem with your car. From what you have described, you may have just drained your battery down. Think of your battery as a bank account with a limited amount of money in it. As you drive your car at highway speeds, you are putting money into the bank (charging the battery), as your car sits and idles with your window defroster, stereo and headlights on, you are withdrawing money from the bank. Eventually you will run out of money and the car will die. The battery may be weak in your car or it may be not have sufficient capacity. The more expensive batteries with higher amp ratings normally have “more money in the bank.