battery charging

Is it possible to charge the battery with a battery charger while the battery is still in (and connected to) the car? Or would this be bad somehow for the PA's (1991) electronics?

No problem, if you follow the charger instructions Click Here (http://www.battery-chargers.com/Instruction%20English.pdf) . I prefer an automatic charger that will shut off when the battery is fully charged & maintain the battery @ full charge until you remove the charger. If the car is in storage for more than a few weeks at a time, it would be best to use an automatic "battery maintainer" rather than a charger.