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Lithium Ion 12v battery?

Cottonwood

Roadster#433, Model S#S37
Feb 27, 2009
5,089
179
Colorado
You sure? What is the AH on it?

According to this post from the other Tesla Forum it's a smaller 35Ah battery.
Lithium Ion Batteries are typically 70% lighter than the same size lead battery.
Lithium Ion Batteries can last 3000 - 5000 cycles whereas lead batteries last 300 - 500 cycles.
I agree that replacing with a Li-ion cell would be a good idea based on the high OEM failure rate.

As an example, here is a 12V, 34AH, AGM battery that is 26 lbs shipping weight: 12 Volt 34 AH AGM Battery I'm sure that the battery itself is 25 lbs or less. A 70% saving on the weight of this battery would be 17.5 lbs.
 

widodh

Model S 85 and 100D
Moderator
Jan 23, 2011
6,860
2,832
Venlo, NL
Ya, pretty sure I am going to get one. If anything, it's nice not to be slinging an extra 50 pounds around for the life of the car.

Interesting. I've been playing with the same idea. I don't want to get stuck and wait for roadside assistance to pick me up.

Although this is really up to Tesla I've been very happy with my Lithium-Ion replacement for my Kawasaki motorcycle. Went from 3,5kg to 700g! That's a serious saving.
 
Late to this conversation, but why, pray tell, wouldn't Tesla make their own in-house 12V lithium battery, are charge it as it is best charged? For a company that is arguably a battery company as much as anything, values vertical integration and makes a fair number of its non-battery components, it doesn't appear to make sense. Hopefully they will in the 3, if time and cost (sans gigafactory) were the primary reasons for going with PbA.
 
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The reason is cost. To get a reasonable capacity, you'd need about 7p4s of cells. That's about $50 alone in cell cost at Tesla pricing.
That doesn't include the investment to setup a whole production line for 12v packs.
They probably pay $35 a pop for the lead acid right off the shelf.

The funny thing is Model S 18650's in 4s are GREAT for lead acid replacement. I have a 12p4s pack I made from Model S cells I've been running in my Ford CMAX for a year now to replace the 30lb lead acid, without even a BMS. It's still pretty well balanced.
a little 7P4S pack has no problem starting a 6.2L Ford V8 as well in testing.
 
Those 12vdc Li-ion batteries advertised use the cheap Chinese Phosphate Cells that are problematic and over rated in capacity. Ask yourself, does any car manufacturer use this chemistry in their EV's? No, with over 15 years experience in the use of Li-ion, I can tell you, LifPO4 is junk. Low voltage and a tendency to sag when used is a problem. I have used a Li-ion Cobalt 12vdc battery in my 85s with excellent results. A BMS assembly on the battery is essential.
 
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FlatSix911

Porsche 918 Hybrid
Jun 15, 2015
7,629
8,021
Silicon Valley
The reason is cost. To get a reasonable capacity, you'd need about 7p4s of cells. That's about $50 alone in cell cost at Tesla pricing. That doesn't include the investment to setup a whole production line for 12v packs. They probably pay $35 a pop for the lead acid right off the shelf.

The funny thing is Model S 18650's in 4s are GREAT for lead acid replacement. I have a 12p4s pack I made from Model S cells I've been running in my Ford CMAX for a year now to replace the 30lb lead acid, without even a BMS. It's still pretty well balanced. a little 7P4S pack has no problem starting a 6.2L Ford V8 as well in testing.

Those 12vdc Li-ion batteries advertised use the cheap Chinese Phosphate Cells that are problematic and over rated in capacity.
Ask yourself, does any car manufacturer use this chemistry in their EV's?

No, with over 15 years experience in the use of Li-ion, I can tell you, LifPO4 is junk. Low voltage and a tendency to sag when used is a problem. I have used a Li-ion Cobalt 12vdc battery in my 85s with excellent results. A BMS assembly on the battery is essential.

Actually, Porsche does offer a lightweight Li-on battery for racing ... for a price :cool:
Suncoast Porsche Parts & Accessories Lithium-Ion Lightweight Battery

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upload_2016-9-29_19-38-54.png
 

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