Should I use Battery Charger/Maintainer to 12V battery?

[freeewilly]

Due to Safe at Home order, I drove a couple miles in the past 3 weeks only, my car is plugged into a Tesla wall outlet most of the time.
From my past personal experience, when Tesla sits there for too long, the 12V battery dies faster. I think it's cause by a lots of deep cycle charging.

Do you think it will help the life of 12V battery when use a battery maintainer?

 

[jerry33]

No reason it should. The car wakes up periodically and will charge the 12V battery. The issues with the 12V BMS were dealt with long ago. (It was an issue in the early days).

 

[CyberShy]

Actually, it probably will help.

How much? Who knows. Can’t hurt.

 

[maximizese]

No reason it should. The car wakes up periodically and will charge the 12V battery. The issues with the 12V BMS were dealt with long ago. (It was an issue in the early days).

From what I understand the issues are still ongoing which is why many 12V batteries from Tesla seem to last between 6-30 months. Some pre-Sentry owners have gotten well over 4 years on their auxiliary batteries. From what I read is that the Model S has quite a bit of vampire drain while the car is off that relies heavily on the 12V battery. Additionally from what I read is that a HV battery with a SOC% >50 will have less strain on the 12V battery when the car is off for days on end.

I do hear an audible click from our 11/13 built S85 while it's sitting in the garage a few times a day. I assume this is the HV contactors opening to recharge the 12V battery. I'm curious if a deep cycle 12V battery would have better longevity than the OEM. I would love a 12V battery sticky thread as we all seem to have questions whenever ours is on the fritz.

Now to address the OP's question, from what I understand a 2-4amp smart battery maintainer can be recommended if the HV battery is below 50% with the car sitting for days. There are battery posts just behind the removable nosecone that some folks use.