Cosmacelf
Well-Known Member
- Joined
- Nov 11, 2020
- Threads
- 18
- Messages
- 419
- Reaction score
- 510
- Location
- San Diego, CA
- Vehicles
- Rivian R1S, Tesla Model X
- Occupation
- Software
The "why do we need a 12V battery at all" question has been raging on the Tesla forums since 2012. And got very heated when Tesla had several year's worth of bad batteries, necessitating emergency swap outs. The answer is always safety. When you get into a crash, the car will blow the high voltage pyro fuse, so even a buck converter would be dead. And you want to have the 12V system still operating post crash. So...
The big innovation Tesla finally, like in the last 6 months, did was to start using a lithium ion battery for the 12V system rather than a lead acid AGM. It should be longer lasting and more reliable. But, it took Tesla many many engineering manpower days to figure it out, and it certainly isn't a cheaper solution. Like all things automotive, it has to be extremely reliable across a very wide temperature range - the main battery pack has a sophisticated Battery Management System along with a heating and cooling system for the battery. The equivalent must be engineered for a lithium ion 12V battery (lead acid batteries are a lot tougher and don't need to be coddled as much).
The big innovation Tesla finally, like in the last 6 months, did was to start using a lithium ion battery for the 12V system rather than a lead acid AGM. It should be longer lasting and more reliable. But, it took Tesla many many engineering manpower days to figure it out, and it certainly isn't a cheaper solution. Like all things automotive, it has to be extremely reliable across a very wide temperature range - the main battery pack has a sophisticated Battery Management System along with a heating and cooling system for the battery. The equivalent must be engineered for a lithium ion 12V battery (lead acid batteries are a lot tougher and don't need to be coddled as much).
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