you need to eliminate the alternator, the way to do this is measure battery drain while the car is stationary, around 30ma is normal,(the speed yours is discharging it should be immediately obvious) more than this then you know there is a problem. if the drain is about correct then it is your alternator at fault (it has a diode that can cause a back current and prevent charging at the same time as draining the battery, test the battery drain before spending any money).
you need to leave the car switched off for 30 min before conducting the test.
you need to leave the car switched off for 30 min before conducting the test.
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