12V battery: convert to a cheap alternative?

[Dee]

I came across this.
It looks pretty simple but what about charging and monitoring the 12V battery?

Normally, the Taycan's 12V battery last for a very long time, some say more than 10 years.
But maybe it's a nice to try for people who are having trouble waking up their 12V battery when it's drained beyond the 12V battery's BMS tresshold (i.e. dead) and don't want to pay topdollar for a new one at the dealership (~€1200).

Sponsored

 

[Vercingetorix]

Driving around with a lower capacity lead acid battery that will be continuously undercharged is not something I would do.

 

[ct14garage]

Driving around with a lower capacity lead acid battery that will be continuously undercharged is not something I would do.

There is nothing wrong with it. Taycan GATEWAY supports AGM batteries, merely coding the Gateway and changing the type from LiFepo$ to AGM is enough to ensure it's always correctly charged.

Porsche just chose the Lithium for the sake of it. They did the same in tje Cayenne and switched back to AGM in 2025 models onwards.

Changing to AGM is perfectly fine, we've done hundreds of cars literally

 

[Dee]

There is nothing wrong with it. Taycan GATEWAY supports AGM batteries, merely coding the Gateway and changing the type from LiFepo$ to AGM is enough to ensure it's always correctly charged.

Is that why they put that OBD-device in?

 

[ct14garage]

Is that why they put that OBD-device in?

i suppose, I don't do it that way and instead code it to PIWIS to AGM Battery. That way it's absolutely factory and there is no need to use any dongles

 

[Vercingetorix]

Porsche uses

There is nothing wrong with it. Taycan GATEWAY supports AGM batteries, merely coding the Gateway and changing the type from LiFepo$ to AGM is enough to ensure it's always correctly charged.

Porsche just chose the Lithium for the sake of it. They did the same in tje Cayenne and switched back to AGM in 2025 models onwards.

Changing to AGM is perfectly fine, we've done hundreds of cars literally

I won’t even begin to argue, you seem to know better than the factory.

 

[69Mach390]

Porsche uses

I won’t even begin to argue, you seem to know better than the factory.

Wow that’s some serious sarcasm there.

Why would you assume it would be lower capacity or undercharged?

Lithium vs AGM vs lead acid all serve the same purpose in a car and are typically interchangeable as long as they can be charged properly.

The nice thing about the 12v in an EV is that it doesn’t have to do the high load starting cycle.

The downside is that manufacturers tend to put a tiny battery in because of that and the cars are dead on the road if it fails.

 

[Vercingetorix]

Reasons AGM are worse than lithium.

 

[gamueller]

Reasons AGM are worse than lithium.

Yeah, but which is cheaper?

 

[Vercingetorix]

Yeah, but which is cheaper?

Lithium lasts 5x longer.

 

[gamueller]

Lithium lasts 5x longer.

Yeah, but Lithium costs 15x more.

 

[Vercingetorix]

Yeah, but Lithium costs 15x more.

Maybe that Sentra for you. It’s 15x cheaper also.

 

[69Mach390]

Reasons AGM are worse than lithium.

You’re making a straw man argument.

No one suggested AGM was better in anything except price.

You were the one making it sound like AGM wouldn’t work.

Other than AGM only lasting 3-5 years, someone could swap out your lithium for an AGM in the middle of the night and you’d never know. Car would function the same as it always had.

If your factory lithium goes bad, it’s a cheaper alternative. And way cheaper if you don’t plan on keeping your car another 5 years.

 

[Vercingetorix]

You’re making a straw man argument.

No one suggested AGM was better in anything except price.

You were the one making it sound like AGM wouldn’t work.

Other than AGM only lasting 3-5 years, someone could swap out your lithium for an AGM in the middle of the night and you’d never know. Car would function the same as it always had.

It’s inferior in every other way, as the charts show. And may even not be cheaper when the worse discharge characteristics hit. Lower voltage in cold weather=more amp draw. Your AGM battery gets discharged once and it very well could be toast. Lithium continues on like nothing happened. It’s all in the discharge cycles and amounts. AGM can’t keep up.

 

[69Mach390]

It’s inferior in every other way, as the charts show. And may even not be cheaper when the worse discharge characteristics hit. Lower voltage in cold weather=more amp draw. Your AGM battery gets discharged once and it very well could be toast. Lithium continues on like nothing happened. It’s all in the discharge cycles and amounts. AGM can’t keep up.

Maybe? But you’re solving for a problem that doesn’t really exist.

Very few cars come with 12v lithium batteries from the factory. Literally hundreds of millions of AGM batteries make it through winter just fine. And they come with a few years of replacement warranty just in case.

FWIW, I don’t know what I will do if my 12v goes out, but it’s good to have options.

Sponsored