Why my new 12v Battery dead after 3 weeks.

[Berylg2019@gma]

Hello.
I replaced my previous 12v low voltage battery almost month ago - now my new 12v Varta battery is dead again. Why it dies so fast?
I am charging my EV 2-3 times per week. Does it matter which 12v battery brand I choose ?

 

[Regaj]

Why a new 12v battery would fail that quickly is hard to say. It certainly shouldn't.

First question I'd have is the source where you purchased the battery. Online? A local shop? And if it was local, was it a place that specializes in automotive parts? Who installed it?

All that relates to the integrity of the (presumably) new battery you bought. Not everything described as "new" actually is.

Bottom line is you need to have the battery load tested by someone you can trust. I'd think a failing 3-week old battery would fall under warranty.

 

[MP3Mike]

Does it matter which 12v battery brand I choose ?

Brand probably isn't important, but chemistry and specs are. Tesla has the charging profile designed specifically for their battery, and when they change batteries they adjust the settings so the charging profile matches the battery they install.

 

[Flybyglass]

The manual specifications say 33Ah or higher. The factory size is a 51R. Most exceed 33Ah.

 

[Rocky_H]

I'm going to second what @MP3Mike mentioned. There are several types of 12V batteries, and they have some different behavior about how to best maintain and charge them. I'm guessing you put in a different type, and the way the car treats it is not suited to that and prematurely damaged it.