Please please help alternator

[Andy grim]

Ok so I have still disconnected the alternator so can't be that but what I have noticed is last night I disconnected the battery and took a reading of 12.47 and this morning took a reading of 12.43 should it go down this much not even connected to anything thanks for your help on this mate

[itavaltalainen]

Yes, it will always loose a little charge. Idle voltage is only one aspect of battery charge.

Without measuring the current it is difficult to tell why you are loosing some charge when the battery is connected up. Voltage fluctuations with engine running is due to alternator.

[Andy grim]

No the battery was removed from the car a it lost that charge in 12 hours

[itavaltalainen]

Yes I understand that, but you only lost 40mV when it was disconnected which is absolutely normal.

[Andy grim]

Oh ok I see so by discounting the positive lead on the alternator it could still be taking juice off the battery?

[itavaltalainen]

Not the alternator but the car still draws a small amount of current.

[Andy grim]

Well euro car parts swaped the battery over but I think your right about the alternator so that's the next job