12V battery: convert to a cheap alternative?

[Scandinavian]

It's not the battery, it's the car.

Yes I guess it is the system that controls the 12 volt charging. But surely Porsche should have necked that several times since they already had to replace one battery. But at the same time it would not surprise me if there would be a bad cell in the 12 volt battery. Porsche accountants probably specified the absolutely cheapest supplier for it? So that they can charge a premium when kaputt !

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[gamueller]

Porsche accountants probably specified the absolutely cheapest supplier for it? So that they can charge a premium when kaputt !
[/QUOTE

Now you're sounding like a conspiracy-minded American!
(I agree)

 

[Gino]

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.

I’ve used quality AGM batteries in my vehicles for decades as both starting batteries as well as backup secondary batteries in the event the starting battery gets drawn down or dies. They’ve all lasted at least 5 years.
The fact I upgraded traditional lead acid batteries to AGMs because they were more energy dense in the same battery size meant the AGMs lasted longer even though they were 50-100% more expensive than the traditional lead acid flooded cell batteries.
That being said, the space in my Taycan for the Li-Ion battery does not allow for a very big AGM battery which means you can’t get the same capacity as the Li-ion which is also why the smaller capacity AGM is around $100. It’s not an apples to apples comparison. Switching to an AGM downgrades your battery capacity compared to the stock Li-Ion battery at the same dimensions. AGM batteries have a lower energy density than Li-Ion so unless Porsche increases the battery area in newer models to accommodate AGMs from the factory then installing an aftermarket AGM will give less capacity in the same space and will be forced to work harder with deeper discharges. This may or may not impact owners based on their use cases.

If, in fact, the Li-Ion battery in my 2021 Taycan lasts 10 years as people are speculating (since none of these batteries have reached 10 years yet) then the cost/year for the Li-Ion will be roughly $120/year. If it dies after 8-10 years that’s acceptable to me. I plan to keep my Taycan indefinitely so I’ll stick to the Li-Ion.
If my battery dies within my 8 year bumper to bumper warranty then Porsche will replace it but if it dies between 8 & 10 years worst case then I’ll replace it with the same battery for $1200 to $1500(future cost) and be good for another 8-10 years.
It is also likely by 2030 when my 12V battery is 8 years old there will be more competitively priced Li-Ion battery options at that time which will cost less than $1000 making the Li-Ion the more reliable & cost effective option going forward IMO.

 

[Dee]

Yes I guess it is the system that controls the 12 volt charging. But surely Porsche should have necked that several times since they already had to replace one battery.

It must be very frustrating to deal with this issue, both you and your dealer.
There are just some cars that have this virus so to speak; one is doing fine for more than 6 years, the other one dies within days if not driven.....
Very frustrating.

 

[Vercingetorix]

I’ve used quality AGM batteries in my vehicles for decades as both starting batteries as well as backup secondary batteries in the event the starting battery gets drawn down or dies. They’ve all lasted at least 5 years.
The fact I upgraded traditional lead acid batteries to AGMs because they were more energy dense in the same battery size meant the AGMs lasted longer even though they were 50-100% more expensive than the traditional lead acid flooded cell batteries.
That being said, the space in my Taycan for the Li-Ion battery does not allow for a very big AGM battery which means you can’t get the same capacity as the Li-ion which is also why the smaller capacity AGM is around $100. It’s not an apples to apples comparison. Switching to an AGM downgrades your battery capacity compared to the stock Li-Ion battery at the same dimensions. AGM batteries have a lower energy density than Li-Ion so unless Porsche increases the battery area in newer models to accommodate AGMs from the factory then installing an aftermarket AGM will give less capacity in the same space and will be forced to work harder with deeper discharges. This may or may not impact owners based on their use cases.

If, in fact, the Li-Ion battery in my 2021 Taycan lasts 10 years as people are speculating (since none of these batteries have reached 10 years yet) then the cost/year for the Li-Ion will be roughly $120/year. If it dies after 8-10 years that’s acceptable to me. I plan to keep my Taycan indefinitely so I’ll stick to the Li-Ion.
If my battery dies within my 8 year bumper to bumper warranty then Porsche will replace it but if it dies between 8 & 10 years worst case then I’ll replace it with the same battery for $1200 to $1500(future cost) and be good for another 8-10 years.
It is also likely by 2030 when my 12V battery is 8 years old there will be more competitively priced Li-Ion battery options at that time which will cost less than $1000 making the Li-Ion the more reliable & cost effective option going forward IMO.

The video shows a 40ah AGM battery same as the Taycan lithium. Who knows if that’s accurate though, I’m still contemplating some 80,000 lumen reverse lights.

 

[Gino]

The video shows a 40ah AGM battery same as the Taycan lithium. Who knows if that’s accurate though, I’m still contemplating some 80,000 lumen reverse lights.

If the AGM battery is the same size/volume in cubic inches to fit in the existing area the Lithium ion battery is located then there is no way the AGM battery has the same capacity.

Lithium-ion batteries are dramatically more energy-dense than AGM batteries of the same size—typically 3× to 10× more, depending on the specific chemistry.

There is no problem swapping out the Li-ion battery with an AGM battery of the same dimensions but the capacity of the AGM battery will be significantly lower in capacity due to it’s much lower energy density.

 

[Vercingetorix]

If the AGM battery is the same size/volume in cubic inches to fit in the existing area the Lithium ion battery is located then there is no way the AGM battery has the same capacity.

Lithium-ion batteries are dramatically more energy-dense than AGM batteries of the same size—typically 3× to 10× more, depending on the specific chemistry.

There is no problem swapping out the Li-ion battery with an AGM battery of the same dimensions but the capacity of the AGM battery will be significantly lower in capacity due to it’s much lower energy density.

Regardless the useable capacity is about 50% of the lithium.

 

[Gino]

Regardless the useable capacity is about 50% of the lithium.

Easily 50% less capacity if the rated capacity of 40Kwh was available in the same size.
I’ve had to double the size of my AGMs to avoid deeply discharging them to get 5-7 years lifetime. Every time you drive an AGM battery below 20% you take years off its life. The Li-ion doesn’t get damaged from deep discharge.

 

[d00d]

I've used a $650 EXT1200 LiFePO4 in my GT4 since 2017, it's 600 CCA instead of 660, but should be close enough.
They also have $900 ETX1600 with 760 CCA.
Either one would need a battery mount kit and something custom to connect electrically to that OEM cover.

https://earthxbatteries.com/product/etx1200/
https://earthxbatteries.com/product/etx1600/
https://www.rennline.com/search.php?search_query=battery mount kits
https://rennlist.com/forums/gt4-spyder/932192-0q-pure-white-journal.html#post14689773

Otherwise, looks like a replacement is $1,400;
https://porsche.oempartsonline.com/oem-parts/porsche-battery-pad915105

 

[prj]

Lordy, eight weeks of standing out in the cold in a driveway! Why would you expect anything different?

Because the car has a logic that recharges the battery automatically when it drops low. Why would you NOT expect it to start?

Last winter my Audi with a normal AGM battery was stood outside for nearly 3 months at some point without starting it, also in the cold, and absolutely no problem to start it, and that actually needs some cranking amps to start the V8 nor does it have any logic to top up the battery.

What is this strange expectation that batteries randomly must go flat? They don't. If they do something is broken.

 

[ovonrein]

It is usually the car alarm that drains them over time.

 

[ecko04]

If the AGM battery is the same size/volume in cubic inches to fit in the existing area the Lithium ion battery is located then there is no way the AGM battery has the same capacity.

Lithium-ion batteries are dramatically more energy-dense than AGM batteries of the same size—typically 3× to 10× more, depending on the specific chemistry.

There is no problem swapping out the Li-ion battery with an AGM battery of the same dimensions but the capacity of the AGM battery will be significantly lower in capacity due to it’s much lower energy density.

Yes, we hear what you’re saying and I tend to agree if they had managed to wedge a 100Ah H3 battery in there but the use case in this example doesn’t hold true.

Like someone mentioned, this may be an area where Porsche didn’t opt for the better engineering or supplier because H3/LN0 AGM batteries definitely have the same, or higher, 40 Ah rated capacity as the stock lithium battery.

 

[d00d]

If H3/LN0 is the form factor, could this $480 LiFePO4 Prius battery be used in the Taycan?

https://www.ohmmu.com/product-page/12v-lithium-battery-for-toyota-prius

 

[ecko04]

If H3/LN0 is the form factor, could this $480 LiFePO4 Prius battery be used in the Taycan?

https://www.ohmmu.com/product-page/12v-lithium-battery-for-toyota-prius

Don’t use that shit. Please excuse my language. Do some google searching across other EVs who have replaced their 12v batteries with the Ohmmu and they’ve failed, and in some cases spectacularly so.

Yes, form factor wise it’ll fit but no from a QA perspective.

 

[d00d]

Thanks, is there a reliable H3/LN0 form factor 12v LiFePO4 battery available from another manufacturer?

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