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Will the Model 3 be the first Tesla to use a 48 volt system?

Discussion in 'Model 3' started by Falkirk, Oct 26, 2016.

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  1. Falkirk

    Falkirk Member

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    I think it would make sense for Tesla to be planning for this, I'm just not sure if they would make the change first to S and X then to the 3 or even just continue using the current 12 volt system. I understand it's been the source of many issues for owners and with the new auto pilot hardware using even more power this might avoid having the 12 volt battery die prematurely.

    This article explains it's coming for ice cars as well:

    The 12-volt car battery is about to be a thing of the past

    Read more: The 12-volt car battery is about to be a thing of the past

    Seems like the costs are high though so for the M3 it just makes it even harder to meet the $35k US price but we really can't have the same battery problems at the scale of the 3.

    I'm hoping Tesla can help themselves avoid issues and give us an awesome car from day one.
     
  2. JeffK

    JeffK Well-Known Member

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    This costs extra money and benefits "fuel economy" ... Not sure where it would fit in the Model 3 realm.

    Might be an easier/cheaper fix to make the 12 volt a LiIon
     
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  3. Saghost

    Saghost Active Member

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    I'm not really sure that a 48V system has anything to offer an EV. The main things they want it for are starter-generators and electrified turbochargers.

    In a Modern EV, anything they needs a lot of power is running off of 400V DC anyway, so stepping up to 48V won't really help.
     
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  4. jbcarioca

    jbcarioca Active Member

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    The Delphi demonstrations have been interesting but misleading IMHO. Once widespread use of 48 volt systems arrives, which it is doing rapidly, the costs will decline to make a net negligible difference from 12V. Because the amperage will drop there will be less stress on connections, the stability of electric components will improve and electrical efficiency will be improved so will be more durable and stable. If current European plans and industry discussions are to be believed (Automotive News has been reporting on this for a few years now) we can expect the next generation of nearly everything from BMW, MB, VW Group, PSA and probably most of GM, Ford and FiatChrysler with 48V. Most of that will probably happen with new model introduction so will be a wave from 2019 model year until, probably, 2021. One Audi model is already being so equipped.

    It will be almost a certainty that Model 3 will be 48v and that the other Tesla models will convert to 48V about the same time. Tesla may be an early adopter, but not by much and it probably will not cost extra to do it. Just remember how much warranty costs will decline and how much improved efficiency and reliability will ensue. 48V A/C and BMS alone will pay for the conversion. Most importantly Delphi has made all their Demo vehicles with ICE, using 48V electric turbochargers etc to increase fuel economy. It is all that gear that costs extra, not the basic electrical capacity.

    Maybe I am not correct about this but I strongly believe it.
     
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  5. JeffK

    JeffK Well-Known Member

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    I would hope so because every source I see says it'd add $800-1200. No idea what it'd cost to replace that before it the costs decline.
     
  6. jbcarioca

    jbcarioca Active Member

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    My previous point explains part of this. The BMS and A/C systems use lots of power and 12V is inefficient and short-lived in comparison to 48V. All the other electrical equipment from displays and controls to sound will be more efficient and cost less when moving to 12V. The precise analogue is to teh changeover from 6V to 12V in cars. 6V could not handle A/C, nor could it deal with evolving complex radios and controls, so the entire auto industry switched in only a couple of years. This pitch, dominated by Delphi, is ICE-efficiency oriented because of the US industry push to meet 2025 emissions and efficiency standards. That actually missies teh major point, that electrical loads have reached their limits for 12V systems.
    The only reason Tesla did not have 48V in 2012 was that all the third party gear was made for 12V. Now it is about to change to 48V for everyone. or almost everyone.
     
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  7. Chopr147

    Chopr147 Active Member

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    I hope they do. The re-fresh Model S 12V battery is very hard to get to. You have to take apart the HEPA filter area just to access the battery. I sure hope my 12V never dies.
     
  8. jbcarioca

    jbcarioca Active Member

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    That Delphi number is for all the electrically-operated turbochargers and engine controls too. Remember that Delphi is a Tier 1 supplier trolling for lucrative contracts for engine controls. They'll not make too much money from the BEV market because that is not their primary specialty.
     
  9. JeffK

    JeffK Well-Known Member

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    Besides the Drive PX2, many of the systems in a Tesla are lower wattage than a traditional car (LED headlights, 4W radar, etc).

    Keep in mind they've been saying we should go with 48v in cars for the last 20 years.... it's still not here.
     
  10. jbcarioca

    jbcarioca Active Member

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    True, but the A/C and BMS are real power hogs, and that will not change much. Anyway, the sheer number of electrical components is increasing and their collective draw is still increasing despite better lighting efficiency. The Drive PX2 is not exactly a miser in power consumption, nor are the rest of vehicle automation systems. A quick look at orders placed and supplier plans for 2017-2020 and thereafter proves that the 48V systems are finally happening, almost thirty years after both Toyota and Nissan planned them for the first Lexus and Infiniti. They gave up then because of cost. This time it is real. That Audi SQ-7 is the first, but just barely. The changeover is driven by ICE efficiency, to be sure, but that gives the scale to0 make all those other components convert also.
    Audi SQ7 TDI packs 48V electric compressor, 664 lb-ft
     
  11. Saghost

    Saghost Active Member

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    Are you talking about the A/C blower fan, that uses maybe 200W of power on high?

    Or did you mean the compressor, which is a 400V DC device?

    What part of the BMS do you think uses lots of 12V power, and why?
     
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  12. Falkirk

    Falkirk Member

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    Thanks for all the comments, I can't pretend to know much about this but looking forward to other's comments and to see what Tesla does with this in time.
     
  13. jbcarioca

    jbcarioca Active Member

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    Actually I miswrote in my reply. I am definitely not an expert so I sometimes make elementary errors. Please accept my apologies for that. I do not know how much energy is used in any part of the Tesla systems, nor any specific loads placed on the 12V systems.
    The specific systems that have been mentioned in the documents I have seen, and reread just now, are:
    1. Steering;
    2. Driver assistance systems (the reference discussed "decision management" (the term included database processing, analytics, external image processing and decisioning and decision presentment) both the actuators and controls for steering, navigation, braking, speed control plus "sensors" (they listed six types (including radar and Lidar so not all apply to Tesla);
    3. active suspension;
    4. air conditioning and ventilation (this excluded compressor but mentioned seat heating and cooling);
    5. vehicle displays;
    6. vehicle controls (this referred to windows, doors, seats, sunroofs and other actuator initiated physical movements);
    7. Audio and other entertainment systems.

    This came from another manufacturer, not Tesla. I left out the myriad ICE and Hybrid-specific issues. This manufacturer listed ICE (differentiating between several types conventional OTTO, Atkinson and variants, Diesel); hybrid and BEV. Each of the three other than BEV had a number of engine management tasks deemed to be 48V candidates. Although it was too technical for me in several respects the interesting general issue is that they thought the change from 12v to 48v would incorporate retention of some 12v systems in transition (just as Audi and Bentley are doing now) but expected to have 48v as a standard for most non-motive-force items by 2025 at the latest. They also anticipated 400v (some debate about other voltages) for high-power systems.

    One interesting generalization is that this manufacturer is trying to reduce the role of ICE as much as possible, replacing it with a fairly wide variety of electrical systems in an effort to reduce the energy loses implicit in historically engine-driven components. To that extent this seems quite similar to the "more electric" campaign Boeing employed in the B787 and is now applying in other programs. Those are all intended to minimize the losses in traditional engine driven compressors, pumps, hydraulic systems etc.

    In a couple of supplier documents i saw there was expectation of savings in weight and cost for wiring, connectors and power transmission as a result of change from 12V to 48V in the categories other than active suspension. Those varied from 12-20% cost savings. Active suspension was presented separately from the other topics and i did not see that piece.

    I cannot directly quote any of these references, but there are numerous industry white papers on the 48V transition, as well as a fair number of symposia and conferences.

    I hope this clarifies my thoughts. Without any question more and more automotive electrical use will be higher voltage than in the past and much will be 48V. The only question is how long 12V endures. I think it will not endure for long, if only because of the weight reduction and electrical distribution efficiency that comes from reduced amperage. We shall see.
     
  14. Saghost

    Saghost Active Member

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    #14 Saghost, Oct 26, 2016
    Last edited: Oct 26, 2016
    Tesla is using electric steering and brake actuators, and has an electric air compressor for the suspension - all of which can probably be shrunk by going to 48V.

    My point, though, is that the benefits to Tesla are pretty small, since they don't have any really hungry 12V systems to start with, so I doubt they will put any effort into leading that conversion.

    Once a lot of the industry goes that way and all of the pieces are there and just as cheap, then they'll probably do it - but they have better things to worry about and the gains from the conversion for a modern EV are very small.
     
  15. timk225

    timk225 Member

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    If it ain't broke, don't fix it. Anything Tesla needs 48 volts for, they can tap it off the main battery.
     
  16. SageBrush

    SageBrush Active Member

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    Can you estimate savings in overall Wh/mile ?

    For now my WAG is 10% improved efficiency for an average power draw of 200-300 watts for accessories. That works out to 20-30 watt savings, so perhaps 5 - 10 Wh/mile. Is that anywhere near ballpark ?

    I do think you make a valid point though regarding reliability that may trump everything else.
     
  17. JeffK

    JeffK Well-Known Member

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    Most vehicles or planned vehicles with 48 volts use a dc/dc converter to still use 12V...

    The DC/DC converter in a Tesla can output 9-16V and is rated for 2500 watts... Why convert twice when you don't need to? There is plenty of power.
     
  18. SageBrush

    SageBrush Active Member

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    That thought crossed my mind too, but I presume that as 48v end loads become common place the 12v converter will have diminishing utility.
     
  19. Drewflux

    Drewflux Member

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    The ICE industry could easily jump to a 24v system that is more common in industrial applications. Plenty of alternators, globes ect.. already out in the field.
     
  20. Drewflux

    Drewflux Member

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    I doubt Tesla will move down this path. If I were them I would redesign the dc-dc converter for a lithium 12 volt battery. Its still far cheaper to get get mass produced electric supplies for a 12v system
     
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