My 172 keeps eating alternators

[clioboy25]

hi all

had a test done on my 172 and the alternator aint powering up the battery,this be the second time in 3 weeks that its been changed,its been changed 3 times altogether.

any ideas?

 

[Budgie]

Fucked battery?

 

[clioboy25]

when i rev my car with the tester it just says 12 on it so the alternator aint charging the battery?

 

[MicKPM]

What alternators are you buying and have you checked to make sure the exciter line is putting out 12v?

 

[clioboy25]

whats the exciter line? how do i check that mate?