Checking the generator or alternator
Dying battery ? It is worth checking the alternator or the generator to make sure it is delivering current properly to charge the battery. To do the generator or alternator check you will need a voltmeter. The instrument is very affordable and you should be in a position to check out your alternator or generator.

Start the engine. If the alternator or generator is doing its job you will see that the voltage measured across the battery rises with the speed (rpm) of the Bus.

Does your alternator or generator fail to rise to 14 volts (across the battery.) This does not necessarily mean that the alternator or generator needs replacing. The problem could be in the voltage regulator. This is a much cheaper problem than alternator or generator replacement. Have a helper rev the engine to over 2000 rpm, but slowly. If the voltage across the battery gets over 14 then the regulator and alternator (or generator)are fine. If not then your first and easiest check, if you have a generator, is to check the brushes in the generator. You can remove the generator brushes and check for wear. You can even push down on the generator brushes and look at that voltage. If you can force the voltage above 14 then you should replace those brushes. Generator brushes are cheaper than a new generator.

Check and clean all contacts. Clean up all contacts. It is not inconceivable that a generator or alternator replacement has fixed things up because of reconnected contacts in wiring !

More Checks: There is much more ! It is worth getting either the DVD on electrical work, or that excellent work "How To Keep Your Volkswagen Alive" which systematically cover the entire electrical system with particular emphasis on the Bus alternator and Bus generator.