battery replacement?

I personally would not do this, because (1) it runs the
battery down unnecessarily, and the alternator is not
designed to re-charge the battery; and (2) re-charging the
battery using the alternator stresses the alternator and
reduces its life.

"z" > wrote
You can always "test" the battery, as long as you have
jumper cables
and another car. A good battery ought to have enough reserve
to keep
the headlights going (with the engine off) for 10 minutes,
then still
start the car. If it doesn't, is when the jumper cables and
other car
come in. How long it can keep the headlights on and still
start the
car is a reasonable measure of how much reserve it has left.