12 volt battery bricks our fortwo

  • We have a 2015 Smart Fortwo with 27,000 km that we have had for 1 1/2 years. We bought the car with 20,000 km, it had been owned since new by a retired couple who trailered it from the West Coast of Canada to Palm Springs every winter on a golf cart trailer behind their motor home.


    Last May the 12 battery light was on one morning, the battery showed no voltage on a test. I went to Mercedes, got a new battery and installed it . A new note showed up on the dash and the new battery had lost quite a bit of its power. It took a quick charge well, then I took the car to my mechanic who initialized it with his computer.


    The Smartie ran for three more weeks , the low battery light came on twice more but went out when I charged the 12 volt battery. The “ tow for service “ light came on one morning and I had it towed to Mercedes. They said the hv battery fuse had blown and the battery needed to be replaced. Their report said “ Code P1D799A Contactor of the high voltage battery module had been opened due to a release fault.”


    Mercedes suggested a repair shop in Portland, Oregon. That shop initially felt they could fix the hv battery if I shipped it to the but when I had the battery removed and sent them the part numbers they stopped returning my calls. I took the car and battery home and put it in the garage.


    Ha! New hobby, interesting one too. ^^


    It was November before I got back to the Smart Ed but I had been reading the internet in my spare moments. No one repairs hv batteries around here. This is the first semester the local trade college has a course but they don’t want the Smart car because Mercedes are hard to work with.


    I did find two possibilities, this site and a company in Eastern Europe but neither could diagnose the problem without a complete list of fault codes and it took a lot of effort to get the dealer to cooperate.


    In addition to the fault listed above they include

    Code
    P1614FA - Control unit internal fault initialization was unsuccessful current and stored.
    P180D1D - Control unit High voltage battery was performed a system shutoff.  The current value is outside the permissible range current and stored.
    P180D64 - Control unit High voltage battery has performed a system shutoff.  There is an implausible signal current and stored.

    ..unable to erase faults as suggested by DAS.


    I have removed the BMS and the 450volt fuse from the battery . The fuse has continuity, I think it’s fine. I’m wondering if the Mercedes front end man meant it was the HV contactors that are not working.

    I see on this site it is prudent to change the 12 volt battery every three or four years and to disconnect the hv battery with the red switch at the drivers left knee before starting work.


    We are anxious to get our little car on the road again but I don’t want to monkey with the hv contactors if they are fine.

    Tha hv battery has 118.3V, 118.3V and 118.4V in the three blocks of cells currently (no pun intended). I think the hv battery itself is okay. We are hoping it is possible to send the BMS away for repair.


    Seems like I have a new hobby now too. While it has been interesting reading about electric cars. I am hoping to get back to driving it.


    I hope this blog is helpful to some readers and that someone will have some thoughts. My thanks to Moritz for organizing this site and encouraging me to post.


    -60yellowbird.

  • Their report said “ Code P1D799A Contactor of the high voltage battery module had been opened due to a release fault.”

    That can be anything. That's just a symptom, not the cause of the error.


    The fuse has continuity, I think it’s fine.

    I would think so as well, yes. :)


    I’m wondering if the Mercedes front end man meant it was the HV Contactors that are not working.

    Could be, rarely they actually break. The fuse, on the other hand, never went off in any smart I know or heard off.


    We are anxious to get our little car on the road again but I don’t want to monkey with the hv contactors if they are fine.

    You can check, if they are still good, by applying 12 V to the appropriate terminals, they should close. You can hear, that they close and you should also be able to measure that they are closed, if they are.


    Tha hv battery has 118.3V, 118.3V and 118.4V in the three blocks of cells currently (no pun intended). I think the hv battery itself is okay. We are hoping it is possible to send the BMS away for repair.

    Of course, I always like selling a BMS reset, as it helps out the page. But in your case I don't thing you need one. Right now I would check the contractors.


    CodeP180D1D Control unit High voltage battery was performed a system shutoff. The current value is outside the permissible range current and stored.

    That would sound like a dead current sensor. But I can't think of a way you could have damaged that by simply driving around with your smart. (Also checked the German version of this error message, which confirmes, that is seems to be the current sensor)


    But if it actually would be the current sensor, the usual error code is "P0AC029". So, as said, I don't think it's the current sensor.


    Did they provide you with the whole PDF, which has got all the error coded of your smart?

    smart fortwo Coupé 451er ED 3,7kW-Lader, 05/2013; > 250.000km (bei 250.000 km 22 kW nachgerüstet)

    smart fortwo Coupé 453er EQ 22kW-Lader, 05/2018 - 05/2021; 109.000km

    smart fortwo Cabrio 453er EQ 22kW-Lader, EZ 04/2021; > 15.000 km


    "Aus Gaspedal wird Spaßpedal"

    - Smart

  • You certainly aren't the first 451 owner to have this issue caused by the 12v battery going bad.

    His HV battery is still fully charged (118 V each pack, that's about 90 % charge). So it's something different than what we know and discussed at other places.


    Usually the 12 V batterie dies and takes the HV battery with it, but in this case the HV battery is still looking good, no deep discharged cells.

    smart fortwo Coupé 451er ED 3,7kW-Lader, 05/2013; > 250.000km (bei 250.000 km 22 kW nachgerüstet)

    smart fortwo Coupé 453er EQ 22kW-Lader, 05/2018 - 05/2021; 109.000km

    smart fortwo Cabrio 453er EQ 22kW-Lader, EZ 04/2021; > 15.000 km


    "Aus Gaspedal wird Spaßpedal"

    - Smart

  • Yours sound's like the usual deep discharged battery. I've wrote a article about that topic: smart ED3 17.6kWh battery repair (feat.P18051C / bricked BMS)

    smart fortwo Coupé 451er ED 3,7kW-Lader, 05/2013; > 250.000km (bei 250.000 km 22 kW nachgerüstet)

    smart fortwo Coupé 453er EQ 22kW-Lader, 05/2018 - 05/2021; 109.000km

    smart fortwo Cabrio 453er EQ 22kW-Lader, EZ 04/2021; > 15.000 km


    "Aus Gaspedal wird Spaßpedal"

    - Smart

  • You don't need a 300-500 V 10 A labor unit. You can also get one with 120 V and charge module by module. And 1-2 A are still plenty for the job. :)

    smart fortwo Coupé 451er ED 3,7kW-Lader, 05/2013; > 250.000km (bei 250.000 km 22 kW nachgerüstet)

    smart fortwo Coupé 453er EQ 22kW-Lader, 05/2018 - 05/2021; 109.000km

    smart fortwo Cabrio 453er EQ 22kW-Lader, EZ 04/2021; > 15.000 km


    "Aus Gaspedal wird Spaßpedal"

    - Smart

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