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https://www.boards.ie/discussion/2055940817/signature-rules

2nd Hand EVS and SOH

  • 07-02-2024 7:32pm
    #1
    Ev fan
    Registered Users Posts: 192 ✭✭


    There's chatter in the UK currently about the need for dealers to provide SOH readouts for 2nd hand EVS to potential customers. The goal of course is to alleviate customers concerns about excessive battery degradation and maybe help sales. If I was in the market for say a 3-year-old ID3 for example I would want to see some documented proof of current SOH for the car - not something I believe dealers can easily provide. We all know that GOM readings cannot be relied upon and apparently SOH measurements involve a protracted process of running the battery down close to zero and then recharging to 100% using the dealer equipment to be able to get an accurate SOH readout. Would you buy an older 2nd hand EV without an SOH certificate?



Comments

  • #2
    the_amazing_raisin
    Registered Users, Registered Users 2 Posts: 11,680 ✭✭✭✭the_amazing_raisin


    So in the case if VW, the battery SOH can be read directly from the car using an OBD scanner

    However you're correct that this is only an estimate, in truth there is no way to "know" the energy content of the battery

    So the battery health is often an estimate based on the age and number of charging cycles, plus how often the battery was charged above 80% in the case of a VW (they do track that)

    There's also test equipment from independent companies that can estimate battery health for a particular model, again based on a pool a data they've collected from testing

    The health can be more accurately estimated by running the car down to a very low SoC (ideally until it turtles) and then charging it and measuring the amount of energy charged into the battery (not the amount of energy supplied by the charger, this doesn't account for charging losses)

    The theory being that energy in equals energy out and thus you can get the "true" capacity

    Unfortunately even this is only an estimate because depending on the discharge rate the available capacity of the battery changes due to heat losses from internal resistance

    I doubt many dealerships are going to drive every EV they get for several hundred kilometres just to check the range. Frankly I wouldn't trust most of them to check the tyre pressure before flipping the car

    So you're stuck with the estimated value, but luckily this is probably fairly accurate. The great thing about Gaussian distributions is that most things stick close to the average value, and I'm going to guess the estimated battery health is very conservative to avoid a bunch of replacements under warranty

    If I was buying a second hand EV from a dealership I'd ask for a battery health report, or I'd ask if I can plug in an OBD11 scanner and read the value myself. If buying private I'd also ask about using a scanner

    "The internet never fails to misremember" - Sebastian Ruiz, aka Frost



  • #3
    Clo-Clo
    Registered Users Posts: 5,545 ✭✭✭Clo-Clo


    NExt Eco Car offer a battery testing service

    https://www.nextecocar.ie/services

    EV Battery Testing

    Aviloo EV Battery Diagnostics

    We have recently been appointed the Irish distributor for AVILOO EV Battery Testing & Diagnostics tools in partnership with our UK partners Maverick Diagnostics.

    We offer battery testing and diagnostic solutions to the motor trade and consumers through the FLASH and PREMIUM test products.

    You can learn more or order a test here or contact us directly at evbatterydiagnostics@nextecocar.ie



  • #4
    kanuseeme
    Registered Users, Registered Users 2 Posts: 1,917 ✭✭✭kanuseeme


    Hyundai Ioniq

    up to 2022

    Hyundai Ioniq 5

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    KIA eSoul

    up to 2021

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    https://evwatchdog.net/

    same guy who made the phev watchdog for Mitsubishi Outlander PHEV (up to 2021), Mitsubishi Eclipse Cross PHEV,

    KIA Niro PHEV*, KIA Optima PHEV*, KIA XCeed PHEV, KIA Sorento PHEV,

    Hyundai Ioniq PHEV*, Hyundai Santa Fe PHEV, Hyundai Tucson PHEV.

    * from 2019 and + only

    https://phevwatchdog.net/

    https://www.webdoctor.ie/online-prescriptions/#:~:text=Through%20an%20online%20medical%20questionnaire%2C%20face%2Dto%2Dface%20consultation,to%20booking%20a%20video%20consultation. not affiliated, just being helpful.



  • #5
    Ev fan
    Registered Users Posts: 192 ✭✭Ev fan


    https://www.boards.ie/discussion/comment/121736101#Comment_121736101

    Thanks for your detailed and informative comments. Just to clarify are you sure that the ID3 will give an SOH reading via OBD? Speaking with a VW main dealer some time ago they said it involved a full discharge and recharge process overnight using their equipment to determine SOH.



  • #6
    Ev fan
    Registered Users Posts: 192 ✭✭Ev fan


    https://www.boards.ie/discussion/comment/121736246#Comment_121736246

    Thanks for this - is that something the dealer would be prepared to pay for and then provide documented backup to potential customers?



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  • #7
    Ev fan
    Registered Users Posts: 192 ✭✭Ev fan


    https://www.boards.ie/discussion/comment/121736657#Comment_121736657

    Anecdotally Kia and Hyundai EVS with a 64kWh battery typically show very good SOH even after 3 years with little or no degradation evident. Again anecdotally commenting on a 3-year-old EV showing 100% SOH the dealer said some of the upper battery buffer (3kWh) is automatically used to maintain " 100% SOH ". This is done to keep owners happy after 3 years ownership.



  • #8
    Ev fan
    Registered Users Posts: 192 ✭✭Ev fan


    https://www.boards.ie/discussion/comment/121736101#Comment_121736101

    Just adding to your note on Gaussian distributions - a 3-year-old EV with average mileage would be expected to have battery degradation in the range of maybe 5% to 10%. Buying such an EV of course you would be hoping for 5% max degradation but would perhaps be prepared to accept 10% at the most? A statistical outlier (right tail of curve) is the one you wouldn't want (15% plus) with a more depleted range and more frequent charging needed.



  • #9
    ELM327
    Registered Users, Registered Users 2 Posts: 22,077 ✭✭✭✭ELM327


    https://www.boards.ie/discussion/comment/121738090#Comment_121738090

    This is true for most Kia/Hyundai EVs since the original Ioniq. I had 2 and both had 100% SOH shown even at 150k km

    https://www.boards.ie/discussion/comment/121738172#Comment_121738172

    10% depreciation after 3 years and 40-50k km is not what would happen. Unless you're buying an older, inferior battery EV like the original leaf. My 2011 leaf 24 has 83k km and 70% SOH. My first leaf 24, a 2014 with better battery, was sold on with 110k km and 90% SOH. My first Tesla had 7% degradation at 200k km

    It varies drastically, by EV and by manufacturer. A valid SOH from an app would be great when selling. Most EV dealers (past and present) that sold EVs would usually provide this info.



  • #10
    the_amazing_raisin
    Registered Users, Registered Users 2 Posts: 11,680 ✭✭✭✭the_amazing_raisin


    https://www.boards.ie/discussion/comment/121738015#Comment_121738015

    It does, you can read it using Car Scanner, I think the value is called Total Energy Content

    The test the garage is referring to probably involves using an external battery tester to discharge and recharge the battery to find the available energy

    It's probably as accurate a test as you're going to get, but I doubt that the garage will be doing that for every EV, it's usually more for diagnosing a fault

    "The internet never fails to misremember" - Sebastian Ruiz, aka Frost



  • #11
    Ev fan
    Registered Users Posts: 192 ✭✭Ev fan


    https://www.boards.ie/discussion/comment/121738249#Comment_121738249

    Again thanks for the detailed comments- you are clearly an experienced EV guy. You have validated my feelings of inadequacy with Kia/Hyundai EV owners- I am just a humble Born owner!! I suspect you're right on the higher limits of degradation- 10% after 3 years - although Battery Life- Chris did show that level of degradation with his 3 Yr old ID3 with admittedly a high fast charging ratio. I guess a 3 Yr old EV with a good BMS and generally not abused charging wise should typically give around a 5% result. The problem is you won't know this to be the case unless you are able to get an actual reasonably accurate SOH readout.



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  • #12
    slave1
    Moderators, Sports Moderators Posts: 19,119 Mod ✭✭✭✭slave1


    https://www.boards.ie/discussion/comment/121738431#Comment_121738431

    I used OBD and EVNotify App last week on 4 year old Kona 64kWh original battery EV, SOH coming in at 98.1% with just over 90k kms on the ODO



  • #13
    zg3409
    Registered Users, Registered Users 2 Posts: 6,829 ✭✭✭zg3409


    The battery management system in most cars has a very good idea of state of health of the battery. This system needs to protect the battery from over discharge and over charge and it constantly measures each cell in the battery and calculates how much energy is left in every cell before it switches the car off.

    In the leaf this estimate was displayed to the driver in an easy way to understand and you will hear owners talk about bars lost. Newer cars it's usually relatively easy to read these values back with an odb dongle. Dealers are hesitant to share these figures as it causes concern and possible warranty claims. Used dealers don't know or care.

    The independent device aviloo connects to the car and needs a number of charge discharge cycles achieved by driving the car normally. It still trusts the data reported from.the car in terms of energy used during the driving from 100% to 0%. I am not sure it's worth the time and cost unless you are pushing a warranty claim.in court.

    Most modern cars have batteries that seem to last 10+ years, and most warranty is 7+ years. Most may last 15+ years.

    Post edited by zg3409 on


  • #14
    Ev fan
    Registered Users Posts: 192 ✭✭Ev fan


    https://www.boards.ie/discussion/comment/121739027#Comment_121739027

    Thanks for that. I think if e.g. main dealers were prepared to give SOH readouts for older EVS then this would reassure buyers. In 5 to 10 years time SOH values over time will be well known with statistical analysis. Also of course if the average degradation is low anyway (say 1% per year) then battery SOH will not be a deciding factor.



  • #15
    Clo-Clo
    Registered Users Posts: 5,545 ✭✭✭Clo-Clo


    https://www.boards.ie/discussion/comment/121738032#Comment_121738032

    The last few times I seen them sell a car they advertised as having battery test done

    They sell very few as the owner moved into a role with electric Ireland or something like that from recollection. But he provides a service to buy a specific car if wanted

    Im not aligned to him or anything, was just looking at him to do battery test for me



  • #16
    the_amazing_raisin
    Registered Users, Registered Users 2 Posts: 11,680 ✭✭✭✭the_amazing_raisin


    https://www.boards.ie/discussion/comment/121738431#Comment_121738431

    To be fair, I think Chris didn't do those tests correctly. He based it on 0% being "empty" whereas there's a couple of kWh remaining even below 0%

    It takes something like 15-20km after 0% to fully run out which would correspond to around 2-3kWh

    If you add that to Chris' data then the degradation is more like 8-9% after 3 years which is more along what you'd expect considering the mileage and number of DC charges

    "The internet never fails to misremember" - Sebastian Ruiz, aka Frost



  • #17
    zg3409
    Registered Users, Registered Users 2 Posts: 6,829 ✭✭✭zg3409


    I see done deal are running a Facebook ad campaign showing how kearys do a "battery test" not to be confused with a full battery test independently done. It shows, I guess, that dealers are having trouble shifting used EVs and now realise customers want more reassurance, even if this is a 10 second test.

    https://youtu.be/MVc2o3VhvVI?si=5gLbyw4VctloyBO0

    Here is a screenshot of the ad with a short video and a link to long video embedded above.

    Screenshot_20240819-214018.png



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