UK-POLOS.NET - THE VW Polo Forum

Hi everyone,

My GF's lovely Polo began misbehaving this week and yesterday would not start at all. So I checked it and seems to be a flat battery which upon further check, it was flat. so we charged it up and the car did start just fine.
The issue is that the battery is only 2 weeks old, so I went to check if it's being charged or not by the alternator, and using a multimeter it showed the current to be at 18V-19V, which I am sure means it's over charging.

If it's overcharging could the problem be with the alternator regulator or something else?

Thanks

If you are measuring any VOLTAGE above 14.5V then I think that you have a problem with the alternator.

Have you tried taking that battery off and charging it using a stand alone charger? Really just to make sure that that battery can take on and hold a charge, before digging deeper into why you are measuring 18>19V.

I'm wondering if you are reading the "not very smooth" alternator output due to the battery being duff as it will normally be that that smooths the alternator output voltage, though never I've never measured the alternator output while a duff (open circuit) battery has been fitted to a car.

So back to beginning, find out if that battery is healthy before doing anything else - would be my suggestion.

Thanks for the reply. The battery is new (about two weeks old) and yes we did charge it using a stand alone charger and all reported well, the battery does start the car and seems to hold the charge as well.

It's just that the car sending 18V to it

Feel like a right idiot, realised the low battery icon on my multimeter and after replacing it, it shows 14.5V while engine is running and under revs. With engine is off it shows 12.6V.

Excellent, any one can make a mistake, but you have had the honesty to come back and explain how things worked!