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Lithium Ion 12v battery?

Discussion in 'Model S: Battery & Charging' started by Zybane, Jan 10, 2016.

  1. Zybane

    Zybane Member

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    Anyone know if you switched out the regular lead acid 12v battery with a Lithium Ion, would it cause any problems? Would the Tesla charge it properly? Here are the batteries:

    12 Volt Lithium Battery

    If I found one that fit the battery tray. Longer life, lighter. Would allow my four 12v cameras to run continuously. Just wondering if the Tesla would charge it properly and/or if there would be any issue with the warranty. From what I can find, these standard size lithium ion batteries are even more safe than the lead acid. Plus it will last the lifetime of the car unlike lead acid.
     
  2. Barry

    Barry Member

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    I suspect one problem would be the charging algorithm
     
  3. LargeHamCollider

    LargeHamCollider Battery cells != scalable

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    Don't bet on it lasting the life of the car (though ten years wouldn't be surprising), LFP batteries are good, but not that good. It will charge it, LFP and Lead-Acid both use the same cc/cv charge cycle but if the car ever puts the battery on a de-sulphate cycle (unlikely) you could have issues.

    Only way to know for sure is to try it, I don't think it could cause any serious damage... But I could be wrong.
     
  4. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    That is exactly the issue.

    Lead acid and Li-ion batteries have very different charging methods. The charge controller in the Model S is designed for a Lead Acid batteries and will not charge a Li-ion battery correctly.
     
  5. LargeHamCollider

    LargeHamCollider Battery cells != scalable

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    I don't have a ton of experience with lead acid cells but I'm quite sure that they charge using a cc/cv (constant current constant voltage) charge cycle, just like the LFP cells in the replacement battery. I don't think the "charging method" will be an issue.

    If the "charging method" were an issue it would probably be an issue for all cars not just Teslas.
     
  6. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    Threshold Voltages different, temp coefficients different. Li-ions don't like to sit at 100%, Lead-Acids do. Lead-Acid goes to float Voltage after finish of acceptance phase. The list goes on. On top of that, there are many different Li-ion detailed chemistries. The list keeps going...
     
  7. LargeHamCollider

    LargeHamCollider Battery cells != scalable

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    I hesitate to argue with the great Cottonwood but...

    Threshold voltages different: 4s LFP vs. 6s Pb? Not going to be an issue, especially since the smart battery has LVP and HVP.
    Temp coefficients different: In LFPs favor
    Li-ions don't like to sit at 100%: true for most lion chemistries, false (or really just barrrrely true) for LFP
    Lead acid goes to float: not going to damage an LFP cell

    Again, if these were show stoppers they'd be show stoppers in ALL cars not just Tesla's.
     
  8. widodh

    widodh Model S R231 EU

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    But aren't those Lithium Ion 12V batteries protected by a charging controller in there? They behave like a regular 12V battery since the charging controller regulates a lot of the stuff going on in there. Right?
     
  9. N4HHE

    N4HHE Member

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    I think the battery cited will probably work but question your need to fix something which isn't broken?

    If you desire to power cameras then put a 2nd battery in the car just for the cameras. So that the cameras do not deplete the system necessary to operate the vehicle.

    LiFePO4 batteries are gaining popularity among motorcyclists, but not without compromise. Capacity is about 25% but short term CCA is greater at warm temperatures. At 32°F many can not crank the engine the first time. Contrary to Pb-acid where one is to stop immediately if the engine doesn't turn over the recommendation with LiFePO4 is to hit the locked up starter a second, then pause and repeat up to 5 times. Driving the locked starter heats the battery internally freeing its energy for the next attempt.
     
  10. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    It looks like some producers have included internal circuits to overcome the problems that I mentioned. See Stark Power - Lithium Starter Batteries Energy Storage Batteries FAQ for an example.

    This is Tesla's problem. They did a design with a high "off" power usage, figured that they had plenty of main battery, and ignored the wear on the 12V battery. So far, they are replacing the 12V batteries under warranty. Let them continue to pay.
     
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  11. Calippo

    Calippo Member

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    Another type of battery from Italy:

    http://www.energaitaly.it/images/stories/pdf/brochure_batterie_avviamento_enegra_ita-gb_rev7.pdf


     
  12. jbcarioca

    jbcarioca Active Member

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    Possibly the most (in)famous examples of aftermarket li-ion replacements for either ni-cad or Lead-acid batteries are those of aircraft. There were many problems for nearly a decade, related to charging protocols, discharge protections/protocols, and battery design. There is copious documentation on these issues from NTSB hearings (I attended them on behalf of one manufacturer) and specific application failure events.

    There is zero question that simple plug-replacement of one type vs another, even one specific li-ion chemistry vs another, requires modification in use procedures. We all know that, for example, Tesla has different charge protocols, different tapers, based on series of battery.

    As for replacing the lead-acid 12v in our Model S with anything else it be hooves us to avoid simple generalization and understand that all, repeat all, the 12v systems on the Model S are automotive standard designed for use with 12v lead-acid. Even major auto manufacturers have not yet managed to switch to anything else despite obvious overloading of 12v systems. There has Benin major effort to move to 24v or 48v or even higher that has not happened mostly because of the cost of change and burden of non-standard approaches. Tesla does not have enough scale to fight that battle.

    Among the aircraft, marine and other applications that use more appropriate electrical standards all of them are very, very expensive and are not well-adapted to large scale. These will reach automotive use, of course, but if Tesla goes there before there is industry scale all our standard switchgear, pumps, lights etc will suddenly become far more expensive and difficult to source. Bad idea, fir now.

    I'd love to see li-ion as the low-voltage solution but there is zero chance I'd install an aftermarket solution without comprehensive knowledge of total design, production, testing, etc. if anybody thinks otherwise just look at, say, Cessna aftermarket success and Boeing 787 lack of testing and qc.

    I know now this is a good idea. Doing it properly is a Big Deal. Ain't no game for a hobbyist! At the minimum think voided car warranty. Very possibly think fire.
     
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  13. LargeHamCollider

    LargeHamCollider Battery cells != scalable

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    I don't disagree with anything here, and (as mentioned in the previous post) I think warranty issues would be the biggest deterrent for me. But, If someone wants to shell out $600 for one of these batteries, I suspect it would work.
     
  14. Zybane

    Zybane Member

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    These new 12V lithium batteries have protection features built in, I don't thinking the Tesla charging it DC to DC would be any issue. Also, these batteries are built to replace any cars 12V battery. Swapping out a 12V battery on pretty much any car would have zero effect on the warranty and is a DIY item. Is there anything explicitly from Tesla that says don't touch the 12v battery or not to use Lithium 12v batteries?
     
  15. FlatSix911

    FlatSix911 918 Hybrid

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    The specs indicate these are a direct replacement for 12V lead acid batteries.

    12v.PNG
     
  16. Zybane

    Zybane Member

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    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.
     
  17. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    The 12V AGM in the Model S only weighs about 25 lbs. You will probably only save 10-15 lbs...
     
  18. Zybane

    Zybane Member

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    You sure? What is the AH on it?
     
  19. FlatSix911

    FlatSix911 918 Hybrid

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    #19 FlatSix911, Jan 15, 2016
    Last edited: Jan 15, 2016
    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.

    lithium%20vs%20lead.jpg
     
  20. LargeHamCollider

    LargeHamCollider Battery cells != scalable

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    Let us know how it goes, I'll be paying pretty close attention:smile:
     

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