Yes, a battery should last longer than two years. But sometimes you get a bad one. And yes, your car has an alternator and a pretty expensive one at that.

One easy thing you might try before looking into the battery/alternator is to reset the low battery warning.

After a low battery condition is remedied the warning does not automatically reset. It has to be reset manually.

But these cars can be a little quirky. Sometimes the warning gets triggered when there really is no problem.

If you would like to try the reset here's what to do. It's a weird procedure but I am not making this up. I have done this in my own XC70 which is the same model year as yours.

First, turn the ignition ON without starting the engine. In other words, do not put your foot on the brake pedal, just press the Start/Stop button until all the warning lights in the instrument cluster come on.

Next, turn the headlights ON. That's ON, not AUTO. ON is one click to the right of AUTO. Make sure they are on low beam.

Now press the rear fog light switch six times. On, off, on, off, on, off. This switch is at the lower left of the headlight switch. See page 103 of the owner's manual if you are not sure.

Next, press the emergency flasher switch three times. On, off, on. The flashers are now on. Leave them so until the battery symbol on the upper right side of the instrument cluster (directly above the 'P' in the gear indicator) flashes three times.

Turn off the emergency flasher and put the head light switch to Auto or off, wherever you normally like it.

That's it. Barring any real problem the warning should not come on again.


--
'79 242, '84 DL 2 door, '80 DL 2 door, '89 DL Wagon, '15 XC70 T6 AWD