Battery drain - what is causing it?

[DenisM]

When I first took delivery, I charged the dual battery set up several times following low readings and used the "recondition" function on a Victron 15A smart charger. It's operating normally now. That was 18m ago. The vehicle doesn't do many kms at the moment so I charge it once a week to maintain it.

 

[TheDocAUS]

When I first took delivery, I charged the dual battery set up several times following low readings and used the "recondition" function on a Victron 15A smart charger. It's operating normally now. That was 18m ago. The vehicle doesn't do many kms at the moment so I charge it once a week to maintain it.

A good practice as a smart charger maintains and charges the battery(s) better than an alternator.

A solar panel with the CTEK CTEK250SE does a good job as well, if there is sun around.