When was the last time you put a multimeter on your battery?

[hardchargin40]

Could be that the battery is knackered, but just drains quicker than the alternator can charge it depending on what loads on upon it.

Make sure your earths are in good condition, both the charger to chassis and gearbox to chassis, helps to run a thick earth from the gearbox, and also your lamba/inlet manifold to the battery earth...  from yoof's tuning (or hardhitters, cant remember who did it) advice on a clubpolo sticky a few years back. 

A link to a different one... http://www.clubpolo.co.uk/forum/lofiversion/index.php/t120353.html


I thought a healthly alternator should read 14.4v, and at least above 13.6v for the ECU to use correct engine control parameters.  Correct me if im wrong, but I remember beavis harping on about it all the time when your car wasn't making enough power no matter what you did.

We had my black car on the rolling road at race power motorsport, no matter what you changed, every run came back with 164bhp and same graph plot everytime, peak power at 6600rpm, alternator read 13.4v.  Bought a new alternator, fitted it while down at beavis's, 14.4v reading and car responding a hell of alot quicker and liam came out with me to setup ignition and cam timings on the vernier, devestating performance upto 8krpm... then we blew the charger seal springs again,  


With the alternator... most times its the voltage regulator (that oval/diamond thingy on alt) bushes that have gone, or the solder has broke, 2 philips screws and it'll come out, about a tenner to get a new one or fix the OE one.