D. Dalton wrote:
I installed a new battery in my car just two years ago. That seems a bit
recent for a battery to give out...

Is there an easy way to determine which is giving problems: the battery or
the charging system?

Do the lights brighten when you run the engine? Or to put it another way
if you turn the engine off do the headlights dim a bit? If so it
suggests the alternator is working.

Fanbelt OK?

Is the daily journey long enough to recharge after the starter motor has
been used?

When you fitted the new battery did you tighten the terminals enough?
Could be worth checking.

If the battery is one where you can add water, does it need water?

A £5 voltmeter would be good enough to check if the alternator is
providing a high enough voltage to charge the battery.

Voltage across battery with engine off, sidelights on: 12.5V approx.
Voltage across battery with engine on and at a fast tick over,
sidelights on: 14.6V approx.

Bill