2001 Avensis 2.0 Diesel mysterious battery drain

[AF557]

my 2001 avensis has been going through batteries at a rate of one every 2 months, i'm not sure what's causing it
could this be a faulty alternator or a parasitic draw?

[TonyHSD]

Lol,  yes there is something wrong definitely, could be one or the other or the both problems combined together. Have your checked for charging or parasitic drain when changed? 

[AF557]

2 hours ago, TonyHSD said:

Lol,  yes there is something wrong definitely, could be one or the other or the both problems combined together. Have your checked for charging or parasitic drain when changed? 

yes, just got a Battery charge tester today, need to get the car running again and i'll verify if it's an alternator fault

[AF557]

As suspected, the alternator seems to be at fault.

Is it at all possible to replace it at home?