Alternator output

richiel_7 · Sep 19, 2017

Hi all,

Anyone know the voltage output under load that a GT 1.9 JTD alternator should be putting out?

Been getting an annoying low voltage beep every twenty seconds - doing my head in.

Had alternator and starter and battery checked and they passed - so guessing a bad earth or loose connection somewhere? Also, it's an intermmitent thing - but when it's bad it's beep, beep, beep constantly!

Just had it looked at and alternator kicking out 13.9 V - is that a touch low and if so, is it enough to annoy the ECU enough to keep beeping at me?

thanks

Henrik_45 · Sep 19, 2017

Where did you measure the 13.9V?
Directly on the battery terminal?
The voltage output of the alternator depends on the load and the charge state of the battery and 13.9V don't sound low to me.

The voltage on the battery terminals must not exceed 14.4V else the battery will start to boil.

It is more likely that the ECU sense the voltage at a point that has a bad connection to the battery so the voltage seems to be low.

richiel_7 · Sep 19, 2017

Hi,

thanks for response.

I didn't measure it - the local garage electrician said the alternator output is reading at 13.9v. He suggested that it might be a touch on the low side?

halftone · Sep 21, 2017

Sounds more like a poor connection or earth, to me. Or a knackered battery. The more current being pulled from the alternator, the lower the volts.

Alternator output

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