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
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.