First, welcome to the club - i too have found it useful.
Second, glad you gave the mileage in kilometres, otherwise at over 1.5 million miles we could have put it down to old age!
Third, a couple of guesses: a poor earth, possibly between engine block and chassis, or a low output from the alternator - somewhere in the club i've read detailed instructions for checking this, but a reasonable volt meter should give you about 14.4 volts at the battery terminals with the engine running about 1000 rpm, and about 12.6V 5 mins after you turn the engine off. if you're not getting 14V or so when running, is the drive belt loose or oily?
if it's not these, maybe someone else has a view?