1. Attachments are working again! Check out this thread for more details and to report any other bugs.

I had a cautionary discussion with an electrical engineer friend

Discussion in 'Gen 2 Prius Technical Discussion' started by Jkman, Mar 3, 2023.

  1. Jkman

    Jkman Junior Member

    Joined:
    Dec 17, 2022
    11
    6
    0
    Location:
    TN
    Vehicle:
    2008 Prius
    Model:
    II
    A friend of mine recently retired from the aerospace industry where he was an electrical engineer responsible for specs of batteries and charging systems. His caution without researching Prius specifics is that the original charging system was designed in minute detail for the original batteries. The point was that the Nextcell lithium batteries are different from the original design which could cause problems long term. Again, this statement was based on his experience designing systems in a highly technical and mission critical industry.

    Comments? Also at what temp do your lithium batteries run in the heat on a long downhill? Dr Prius app said mine were at 90*F with outside temps at 70* after an hour drive.
     
    Meg&Bear likes this.
  2. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,571
    48,862
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    doesn't sound like he studied the details enough to make a qualified decision, despite his expertise
     
  3. PriusCamper

    PriusCamper Senior Member

    Joined:
    Mar 3, 2012
    10,770
    4,371
    0
    Location:
    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    Jack's going into the 8th year of testing and refinement of Nexcell upgrades and he's continuing to find ways to make improvements to long term reliability...

    As in all the tests that an Electrical Engineer can think up have been done already. The main point being the battery is upgrading a tiny 1.3kwh battery pack in a way that ensures it's behaves similar to what the car expects, but with slightly more amps and way better performance. Compared to the demands of a 100kwh battery pack like they have in a Tesla Model S the risks and variables involved are much less of a concern by a factor of a hundred fold.

    And clearly, your battery pack, your electric motor and your motor controllers always have to be designed to work together and that's what Nexcell has done in their design in building a pack that is going to behave almost the same way as standard Prius Pack.
     
    #3 PriusCamper, Mar 3, 2023
    Last edited: Mar 3, 2023
  4. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
    7,474
    4,373
    7
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    I would think the EE with specific aerospace battery experience would be well qualified to advise. Everyone hears how the Prius lithium retrofit is designed to emulate such that it "behaves similar to what the car expects" but we don't know how that happens without extra logic. What everyone relies on is they have not caused serious problems do far.
     
    Meg&Bear likes this.
  5. Jkman

    Jkman Junior Member

    Joined:
    Dec 17, 2022
    11
    6
    0
    Location:
    TN
    Vehicle:
    2008 Prius
    Model:
    II
    I would put my friend's knowledge and competence up against anyone. He's qualified to have designed the Prius and he's only recently retired so his knowledge set is still current. He also doesn't have an incentive to get into the details and won't but was simply throwing out a caution.

    I've found from being on multiple forums of several different cars that many "upgrades" either don't perform any better than the original system when it's working as designed or actually work worse. Frequently people repair and compare a worn out broken system with the upgrade and think there is a vast improvement over stock. In this case, the lithium is working and I just want to make sure that it isn't prone to catastrophic failure - for instance starting a fire. Of course that question would have been better asked before the install. I've always been of the opinion that you gather information and make a choice. That way you can change sooner if you have in fact made a mistake.
     
    Meg&Bear likes this.
  6. PriusCamper

    PriusCamper Senior Member

    Joined:
    Mar 3, 2012
    10,770
    4,371
    0
    Location:
    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    You're literally trying to qualify someone's opinion of a system that by your own admission they haven't even studied yet, or as you say "His caution without researching Prius specifics is that the original charging system was designed in minute detail for the original batteries."

    Don't you see the failed logic you're presenting? You claim someone has problems with "minute details" that they haven't studied yet?

    And then you double down with even more vagueness like, "I've found from being on multiple forums of several different cars that many "upgrades" either don't perform any better than the original system when it's working as designed or actually work worse."

    Each "upgrade" is different and just about every upgrade related to Prius has thoroughly been argued about on this forum for decades. We've been talking about Nexcell on here for 4 years now...

    As for you concern about safety, LiFePo4 is the most advanced battery chemistry in production in terms of safety. Read up on the evolution of battery chemistry if you don't believe me.

    That being said, Hybrid cars in general are more likely to catch on fire than a regular car or an electric car because there's more failure points/complexity of systems, but using LifePo4 decreases rather than increases those risks: What car catches on fire the most?
     
  7. Georgina Rudkus

    Georgina Rudkus Senior Member

    Joined:
    Sep 15, 2018
    3,096
    2,163
    0
    Location:
    Taylors, SC
    Vehicle:
    2012 Prius v wagon
    Model:
    Two
    I agree with the OP's posting. I will keep my car within OEM specs. If it came with NiMH batteries, I will keep and replace them with the same batteries from Toyota. More than 20 years of reliability can be denied.
     
    Meg&Bear likes this.
  8. PriusCamper

    PriusCamper Senior Member

    Joined:
    Mar 3, 2012
    10,770
    4,371
    0
    Location:
    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    Nothing wrong with old people loyal to battery chemistry advancement from 1980's that Toyota has been committed to for 30 years because of their patent rights and cost of production/capitalism that put their outdated chemistry at at an economic rather than a technological advantage...

    The rest of us are living 40 years ahead of that braindead level of anti-EV exploitation and we're intelligently finding a far better and safer way with the most advanced, thoroughly tested and reliable battery chemistry that's been far more rapidly deployed/ramped up to date then any of the previous chemistry.
     
    #8 PriusCamper, Mar 4, 2023
    Last edited: Mar 4, 2023
  9. PriusCamper

    PriusCamper Senior Member

    Joined:
    Mar 3, 2012
    10,770
    4,371
    0
    Location:
    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    The more logic and data the better... I'd love to talk every technical aspect and detail with this EE... But as presented that's not even an option. OP is presenting dogma rather than intelligent discussion about the history of the advancement of battery chemistry as related to its most exciting use cases with vintage hybrids.
     
  10. MCCOHENS

    MCCOHENS Member

    Joined:
    Oct 3, 2019
    189
    80
    0
    Location:
    Chalfont, PA
    Vehicle:
    2006 Prius
    Model:
    II
    Modifying any car to improve performance carries risks. If I turn up the boost on my subaru the chance of blowing it up increases. That is why the performance chips for ICE cars carry warnings that it voids the warranty. Toyota did an excellent job of engineering the prius and any changes may or may not affect the longevity. I think that is what the OP's friend meant and agree. To those who have put lithium batteries in, when you get 100K or 200K miles on the system please share the information. Until then I will stick with the stock battery chemistry.
     
    Meg&Bear and Georgina Rudkus like this.
  11. Georgina Rudkus

    Georgina Rudkus Senior Member

    Joined:
    Sep 15, 2018
    3,096
    2,163
    0
    Location:
    Taylors, SC
    Vehicle:
    2012 Prius v wagon
    Model:
    Two
    I'd never do any modifications that void the factory warranty. Also, these modifications, if poorly done, have unintended consequences.

    The standard factory repair manual my not help to troubleshoot the issue. If the technician have to spend time, even if he or she is qualified, you'd have to pay and pay extra.
     
  12. sam spade 2

    sam spade 2 Senior Member

    Joined:
    Mar 31, 2018
    7,035
    2,780
    0
    Location:
    USA
    Vehicle:
    2017 Prius c
    Model:
    Four
    I've said things like that on here several times.
    And some people just don't want to hear the truth.
    That applies to "rejuvenating" worn out batteries too.
     
  13. sam spade 2

    sam spade 2 Senior Member

    Joined:
    Mar 31, 2018
    7,035
    2,780
    0
    Location:
    USA
    Vehicle:
    2017 Prius c
    Model:
    Four
    Sometimes batteries overheat and catch fire.......even when used as originally designed.
    Modifications make that even more likely.
     
  14. Jkman

    Jkman Junior Member

    Joined:
    Dec 17, 2022
    11
    6
    0
    Location:
    TN
    Vehicle:
    2008 Prius
    Model:
    II

    Perhaps to be more accurate I should have simply asked how qualified the people designing the lithium system are, what was done to make sure the factory charging system is compatible with the new batteries and what safety measures are in place. I'll look into LiFePo4.
     
  15. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,571
    48,862
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    I agree he is qualified, but he hasn’t studied the system, so his statement is premature and unreliable
     
  16. alftoy

    alftoy Senior Member

    Joined:
    Mar 16, 2009
    1,130
    505
    0
    Location:
    Saskatchewan, Canada
    Vehicle:
    2008 Prius
    Model:
    Base
    Google:
    Is LiFePO4 better than lithium ion? The LiFePO4 battery has the edge over lithium ion, both in terms of cycle life (it lasts 4-5x longer), and safety. This is a key advantage because lithium ion batteries can overheat and even catch fire, while LiFePO4 does not.

    First of all, LiFePO4 batteries are 100% incombustible, so there is no chance of a lithium iron battery catching fire or exploding.

    How qualified? Seems china is the world leader in design and manufacture of lithium batteries, so quite sure Project Lithium was able to tap into that resource.
     
    #16 alftoy, Mar 4, 2023
    Last edited: Mar 4, 2023
  17. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
    7,474
    4,373
    7
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    Not exactly. Knowing how different battery chemistries require different algorithms is engineering expertise. When you don't have a different management strategy and you are trying to emulate a chemistry without extra logic, there is room for caution from an expert.
     
    Meg&Bear likes this.
  18. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,571
    48,862
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    You’re assuming the level of knowledge about someone you don’t know.
    And your statement about battery management and algorithms has no data to back it up.
    My opinion is, he could be right, or he could be wrong.
    If anyone is concerned that he could be right, they have choices
     
  19. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    23,072
    14,975
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    Rather, rj assumed that a person introduced as an electrical engineer would have basic background knowledge appropriate to an electrical engineer. Now, that might turn out sometimes not to be true of everyone credentialed as an EE, but it's an assumption that gets made all the time, is sometimes written into laws, and is among the safer assumptions being made in this thread.

    Will we demand a sheaf of references from the next person who says gasoline's made of hydrocarbons, too?

    Some things are familiar enough within a field that a simple reminder does the trick.

    The interesting question is, what data do we have on offer to support that Nexcell has in fact made a battery with LiFePO4 such that the Toyota ECU's NiMH-specific management algorithms work well with it?

    I know that we have some number of people driving around with the things who so far have not reported problems, which is good, and that the maker has conducted numerous tests and published numerous results, which is encouraging, but of course is also marketing. I myself am not qualified to judge the coverage or adequacy of the tests that have been conducted or the published results. Camper described them in #3 as "all the tests that an Electrical Engineer can think up". If we've got an actual electrical engineer somewhere, unaffiliated with the seller, who agrees with Camper's description, then great.

    Clearly that can't be the EE mentioned at the top of the thread, who hasn't scrutinized those tests and results published by the seller, and hasn't claimed to. But if there were one, it would strengthen the argument that Nexcell has in fact achieved what is widely regarded, in general, as difficult to achieve.

    Tautology that it is, that's indisputably true. Where it starts getting more interesting is in comparing the likelihood of the two possibilities.
     
    Meg&Bear and PriusCamper like this.
  20. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,571
    48,862
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    Even automakers with all of their engineering know how make dangerous mistakes after exploring every possible detail of their design.
    Someone who hasn’t even looked at the design is simply taking an educated guess.
    Better than most of us, but still not authoritative