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I'm just looking for some general advice.

Today I was driving at around 80km/h when my battery light came on and the car seemed to lose power. When I went to start it, the engine seemed to start (at extremely low revs, around 500rpm) for a second or two before cutting out again. When I got a jump start, the car managed to stay running at those really low revs until I touched the accelerator. I'm thinking it's an alternator, but I'm not 100% sure. I checked the spark plugs, the oil levels, the connections to the battery and ground and could see anything obviously wrong. The car is a 2002 Holden Commodore VX wagon.

Any advice on what could be causing this? Thanks guys.

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    A car will run fine with the either the alternator or the battery broken. What you have here is more likely a problem with fuel. When you push the accelerator, the throttle valve opens up. If there is not enough fuel pumped in for the wider open throttle, the engine dies. Check the fuel pump. – Janka May 28 '17 at 12:03
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Check the battery voltage across the actual battery terminals with a good meter with the car off, and the car running.

A salvagable battery should have at least 12.5 volts with the vehicle off, and 13-14 volts with the vehicle running just off idle.

Also make certain the belt that drives the alternator is tight.

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If your battery light came on, this means your alternator was producing near 0 volts.

The battery light is normally connected between positive end of the battery and output of the alternator. So it comes on if your battery has higher voltage than alternator output.

You should start by checking all the cables connected to alternator is working. Especially the positive input to regulator from battery.

If all the cables are fine. I would suspect the regulator or worn brushes on the alternator. Then you should start by checking brushes.

It is unlikely that windings are broken, but you should check them also with a multimeter.

If windings are good, and brushes are good, you need to change the regulator. It should be removable.

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