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Discussion Starter #1 (Edited)
I have been experiencing an intermittent problem with by beloved 2014 smart ED. The onset of this problem surfaced while using the car MUCH less due to the pandemic coinciding with lower temperatures as the winter season moved into the southern US. The dash will show "Drive Sys Off - EV Workshop" and not proceed to "Start" mode(so not turning on the HV battery). My idea was that the 12V battery was going bad. I will also note that I felt like the miles range was also reading lower than usual during this time. So fact being, my car had been running and sitting idle with an old 12v battery (the original, 7 yrs old) for how long? The error cleared and the car started after putting a charger on the 12v battery so I therefore replaced the 12v battery. It was working fine until shortly thereafter, (and still not driving much/short trips) the temperature dipped one night again and the car would not start in the morning, but would in fact start after the temp. warmed up later that day (we have had wild temp. swings like 30 degrees or more in 24hrs or less). Days later a very unusual winter storm moved into Texas and temps reached -2F and several days of sub 32F. Throughout this entire storm my car displayed the same error and would not start or accept a charge even with the new battery AND with a charger applied for days at freezing temps. So knowing that it had previously started in warmer weather, I decided to wait out the storm and try it when temps returned to around 60 degrees. After several days and 30 degrees warmer the car started! After many occurrences of this phenomena related to outside temperature persisting even after the battery being replaced I am hypothesizing that:

-The 12v system at some point becoming insufficient or intermittent due to low voltage has somehow caused the BMS and HV battery to get out of equilibrium somehow, due to a lack of 12v battery charge, lack of driving, lack of full charge cycles, perhaps explaining the low estimated range and refusal of the drive system to start in lower temps (out of threshold?). Maybe the BMS shuts down the HV after not receiving acceptable info based on historical information? Note: I used to drive this car daily with absolutely no issue in all temps. It all started when I stopped driving it.

I see similar stories on here. My HV battery was never discharged completely that I know of and since replacing the 12V battery and driving it when it's warmed up during the day lately, the range is going much higher. Days ago it was showing 50-55 miles at full charge in mild weather (too low) and today it's showing 77 at full, which seems a bit generous. I have not seen range on my car that high in a long time, so the car seems to be going through some sort of SOC adjustments. It refused to start initially this morning after several tries, but then I turned off the headlights and then it started which may or may not be related.

I will continue to monitor the car and keep a trickle charger on it during the day when it is not in use, and allow the HV battery to go through full charge/discharge cycles to see if the mysterious behavior and error relative to temperature goes away, my hypothesis being that some "bad" SOC parameters in the BMS affected by temperature brought on by the lack of 12v battery charge will go away as 12v system continues to operate correctly and the BMS corrects itself as input data is updated. In other words "was my car charged as much as it (the BMS) THOUGHT it was?" This is all assuming that the BMS is powered through the 12v system? If so, we all know that low 12v batteries can cause strange issues and when you put a BMS in the equation... who knows. Will the error ever happen again? Will it show up again next winter? According to some info on another site, these cars have a 12V draw when off between .3 - 1 amp which is more than a typical car and the 12v battery only charges when the HV battery contacts are closed(when the car is charging), or when its on of course. So lesson be, either use and charge these cars often or keep the 12v on a trickle. In theory the 12V would probably stay charged if the car is continually connected to the EVSE as the car would continually activate the EVSE to top up the HV battery, but I would prefer the car not to remain at 100% SOC for long periods. Anyway I hope the car is able to "recover" fully as time goes on and the BMS and battery are "reacquainted"?. Some other thoughts:

1. Is there a short in wiring or ground somewhere on 12v system? (Maybe, but why is starting dependent on warm temp in my case)
2. Bad relay/switch acts up in cold temps?
3. Wire harness chaffing problem (no, checked that, and not very temp sensitive)

Update 3/24/21

55 degrees out. Attempted to start car and got the error again. I then immediately turned the ignition 7-10 times and the drive system finally came on. This doesn't seem to point to software, but a short somewhere or a problematic or sticking relay. Maybe the problem is just a coincidence to the 12V battery. Also, once I get the car started and drive to a store or something, the car ALWAYS starts. The sitting overnight in cool weather (below 60) is what triggers the condition.
 

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2014 Cabriolet bought in Sept 2016 with 6,470 mi
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Sounds like a water/ice/condensation related short since it only happens in very cold weather.

Have you been replacing the desiccant filter?

One way to test is to warm parts of the car with a heater and see if that solves the problem and thus at least be able to narrow it down to an area of the car.
 

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Discussion Starter #3 (Edited)
Yes, I have replaced the desiccant twice over time, 2nd time just recently. I think I'm on to something now for sure... this morning, 53 degrees, it took me turning the key to position 1 FIFTEEN times before the drive system finally turned on/contacts opened. It is happening in any temp below about 60 degrees F. Once I get it started and drive it somewhere is always starts with one turn of the key after returning to the car(from grocery store, etc.). Perhaps it could also be a weak CAN bus signal that operates better after energization? I'm tending to rule out the fuse box otherwise it would probably occur in the middle of driving. The drive control ECU? I did see that some owners have had trouble with the 22kw charger Can bus connector, but I have the 3.3. When this problem is occurring the car will not charge either, but once I get it started (by turning the key many times), turn the key off, it then will charge. Does anybody know if the HV contactor is located in the pack itself or in the onboard charger unit?
 

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Be sure the 12v battery posts are clean (use the rotary brush tool!) and can carry max amps (use the heaviest 12v load you have to test). Many times I have been flummoxed only to find that I overlooked 12v delivery. Also might be good to have Dealer run their test proceedure. Good luck.
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I expect you meant to say you were turning it to 2 without it starting but just like I do when someone tells me their computer doesn't work I ask about it being plugged in, I am going to state the obvious just in case.

If you have only been turning the starter switch to position 1 it shouldn't ever have started (display shows READY). You have to turn it past 1 to 2 and hold it for at least a beat before it will start (the key always springs back to 1). I occasionally don't hold it long enough and it doesn't say READY and I have to do it again. The manual page is below for reference.

65904
 

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Discussion Starter #6 (Edited)
Yes, position 2 starts the motor, but the HV contactor actually opens at position 1 and starts charging the 12v battery, which is why my car would not proceed to position 2. The "drive sys. off error" is either present or not present at position 1 and then this apparently determines if the car can proceed to start/position 2. What I learned in this problem is that there is no need to try position 2 if I don't HEAR the HV contactor open at position 1...it is a distinct noise. When the error is present that noise does not occur. DealMeln, after I have thought more and more about your theory on my car, it actually makes A LOT of sense! As I said I just replaced my desiccant at the same time I replaced the battery on Feb 20. Importantly to know, I procrastinated on this as it had been 4 years since the last one which is double the MB recommendation of 2 years. Perhaps the absolute humidity is in fact high in my battery and is passing the dew point with condensation causing a short to a circuit that is related to activating the HV contactor. This explains how EVERY time the temp rises the (fog clears) and the car works. Hopefully the new desiccant will bring this back into spec. This morning, 50 degrees, turned key over 20 times - no HV. THEN I attached my trickle charger and the HV system came on, so does just that little extra voltage boost whatever circuit is affected by the condition? So, I can't find any reason to rule out condensation causing the temperature/dew point issue. My plan now is to wait this out, monitor it through the summer here and probably change my desiccant next year(early) as my current one might max out early since I was behind on this schedule. Also, if this is a "mechanical" short rather than condensation short, the problem will persist and worsen through the summer in theory. Thanks for your insight! I was further enlightened after reading the article at this link regarding HV humidity levels and I encourage everybody to read it especially if you think that maintenance item is unimportant. Whitepaper_Humidity-Control-Paper_V1-1.pdf (mann-hummel.com)
 

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Discussion Starter #7
Be sure the 12v battery posts are clean (use the rotary brush tool!) and can carry max amps (use the heaviest 12v load you have to test). Many times I have been flummoxed only to find that I overlooked 12v delivery. Also might be good to have Dealer run their test proceedure. Good luck.
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Posts are immaculate and super tight
 

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Discussion Starter #8
Yes, position 2 starts the motor, but the HV contactor actually opens at position 1 and starts charging the 12v battery, which is why my car would not proceed to position 2. The "drive sys. off error" is either present or not present at position 1 and then this apparently determines if the car can proceed to start/position 2. What I learned in this problem is that there is no need to try position 2 if I don't HEAR the HV contactor open at position 1...it is a distinct noise. When the error is present that noise does not occur. DealMeln, after I have thought more and more about your theory on my car, it actually makes A LOT of sense! As I said I just replaced my desiccant at the same time I replaced the battery on Feb 20. Importantly to know, I procrastinated on this as it had been 4 years since the last one which is double the MB recommendation of 2 years. Perhaps the absolute humidity is in fact high in my battery and is passing the dew point with condensation causing a short! This explains how EVERY time the temp rises the (fog clears) and the car works. Hopefully the new desiccant will bring this back into spec. This morning, 50 degrees, turned key over 20 times - no HV. THEN I attached my trickle charger and the HV system came on, so does just that little extra voltage boost whatever circuit is affected by the condition? So, I can't find any reason to rule out condensation causing the temperature/dew point issue. My plan now is to wait this out, monitor it through the summer here and probably change my desiccant next year(early) as my current one might max out early since I was behind on this schedule. Also, if this is a "mechanical" short rather than condensation short, the problem will persist and worsen through the summer in theory. Thanks for your insight! I was further enlightened after reading the article at this link regarding HV humidity levels and I encourage everybody to read it especially if you think that maintenance item is unimportant. Whitepaper_Humidity-Control-Paper_V1-1.pdf (mann-hummel.com)
See 3.2 in that article
 

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2014ED you're welcome. Interesting that it won't let you turn the key past position 1

I suggest checking the voltage of the 12v battery before you try to start the car when the temp is low and then if the car won't start, charge the battery and try again. Mostly so you can eliminate low voltage on the 12V as the problem since it worked after you charged it up (though it could just be a coincidence and the cause was just the warming past the dew point/drying of the moisture).

When I changed the battery on my 2014 last year, the contactors opened and closed periodically while no battery was connected which is not something that should happen, but is likely why the traction battery gets bricked when the 12V battery dies.
 

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Discussion Starter #10 (Edited)
2014ED you're welcome. Interesting that it won't let you turn the key past position 1

I suggest checking the voltage of the 12v battery before you try to start the car when the temp is low and then if the car won't start, charge the battery and try again. Mostly so you can eliminate low voltage on the 12V as the problem since it worked after you charged it up (though it could just be a coincidence and the cause was just the warming past the dew point/drying of the moisture).

When I changed the battery on my 2014 last year, the contactors opened and closed periodically while no battery was connected which is not something that should happen, but is likely why the traction battery gets bricked when the 12V battery dies.
2014ED you're welcome. Interesting that it won't let you turn the key past position 1

I suggest checking the voltage of the 12v battery before you try to start the car when the temp is low and then if the car won't start, charge the battery and try again. Mostly so you can eliminate low voltage on the 12V as the problem since it worked after you charged it up (though it could just be a coincidence and the cause was just the warming past the dew point/drying of the moisture).

When I changed the battery on my 2014 last year, the contactors opened and closed periodically while no battery was connected which is not something that should happen, but is likely why the traction battery gets bricked when the 12V battery dies.
2014ED you're welcome. Interesting that it won't let you turn the key past position 1

I suggest checking the voltage of the 12v battery before you try to start the car when the temp is low and then if the car won't start, charge the battery and try again. Mostly so you can eliminate low voltage on the 12V as the problem since it worked after you charged it up (though it could just be a coincidence and the cause was just the warming past the dew point/drying of the moisture).

When I changed the battery on my 2014 last year, the contactors opened and closed periodically while no battery was connected which is not something that should happen, but is likely why the traction battery gets bricked when the 12V battery dies.
I didn't mean to intend that it won't let me turn to 2, but it just doesn't do anything or proceed to "Ready" mode. I should have said Ready, not Start. In other words, it won't proceed to Ready mode if the drive sys. off error is present at position 1. No, my battery was full last time... the trickle charger was only off for a day. I just hooked it up again to see if it would help it start and it did after trying 20 or so times(could be a coincidence of course). Interesting, if the contactors opened with your battery out, that might suggest that the HV system actively charges the 12V battery if needed or if it senses low voltage. Is this true? Nobody seems to know. Other EVs do. My understanding from research on here is that the car does not charge the 12v when not charging or off. This morning, 63 degrees, HV system came on with one turn of key, still supporting a possible moisture prob. in my HV battery... internal dew point curve was not crossed last night. Check out this informative explanation of the battery also very interesting 2012 Smart Fortwo HV Battery. - YouTube
 

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Discussion Starter #11
2014ED you're welcome. Interesting that it won't let you turn the key past position 1

I suggest checking the voltage of the 12v battery before you try to start the car when the temp is low and then if the car won't start, charge the battery and try again. Mostly so you can eliminate low voltage on the 12V as the problem since it worked after you charged it up (though it could just be a coincidence and the cause was just the warming past the dew point/drying of the moisture).

When I changed the battery on my 2014 last year, the contactors opened and closed periodically while no battery was connected which is not something that should happen, but is likely why the traction battery gets bricked when the 12V battery dies.
I didn't mean to intend that it won't let me turn to 2, but it just doesn't do anything or proceed to "Ready" mode. I should have said Ready, not Start. In other words, it won't proceed to Ready mode if the drive sys. off error is present at position 1. No, my battery was full last time... the trickle charger was only off for a day. I just hooked it up again to see if it would help it start and it did after trying 20 or so times(could be a coincidence of course). Interesting, if the contactors opened with your battery out, that might suggest that the HV system actively charges the 12V battery if needed or if it senses low voltage. Is this true? Nobody seems to know. Other EVs do. My understanding from research on here is that the car does not charge the 12v when not charging or off. This morning, 63 degrees, HV system came on with one turn of key, still supporting a possible moisture prob. in my HV battery... internal dew point curve was not crossed last night. Check out this informative explanation of the battery also very interesting 2012 Smart Fortwo HV Battery. - YouTube
 

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Discussion Starter #12 (Edited)
Had several days of warm days(70-80s) and had no problems - driving perfectly with no errors present. Temp dropped last night and attempted to start this morning at 57F. "Drive sys. off" error present after about 7-10 times. On the last turned and held the switch in position II for about 3 seconds(normally instantly) and the drive sys./HV battery finally activated and error cleared. I'm still getting the "feel" that there is a weak signal or weak short somewhere and is still dependent on temperature. No improvement at this point. If it were condensation in the HV battery I am wondering how long that should take to correct after installing new desiccant. I am still considering a wire chaffing event, but to my knowledge this would not be temperature dependent.
 

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Still sounds like moisture in the pack to me. One way to be certain is on a cold morning try starting. If it doesn't, pull the desiccant cartridge, use a small heater or heat gun on low for a few minutes to dry out the air in the pack and try starting.

If it starts, you're problem is solved (most likely permanently), if not then it definitely is not moisture in the pack and the short or other electrical issue is elsewhere.
 
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