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Is there a way to park my e smart car for prolonged periods of time without having to have people drive it when I’m away? I often travel for 3-4 months at a time. I wasn’t sure if there was a battery drain and charge device?
 

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E Smart battery saver (electric smart)

Maybe my title should have said “how do you drain the HV batteries for an electric smart car? I need to be able to keep the battery pack (not the 12v) healthy as my car needs to be parked for prolonged periods of time. Is there a protocol or safe way to discharge the batteries without having to drive it on the road? I don’t want to have to have people go into the garage and have to take the car on the road every week or 2 and drive for 60 miles to keep the batteries healthy while I’m away on travels. I can be gone for up to 4-5 months at a time.

Thanks for your help!
 

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As written in my FAQ, just plug in the smart and leaf it as it is. (That's also what the manual recommends) There is no need to drive it every two weeks or something strange like that. As long as it's plugged in, the DCDC-converter of the smart is also charging the 12V-battery.
 

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Is this something new with the newer ones? Because I read in old posts that this could be very harmful for the car. Thanks for the info! I just joined yesterday so I haven’t had to chance to read all the info on the topic.
 

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As written in my FAQ, just plug in the smart and leaf it as it is. (That's also what the manual recommends) There is no need to drive it every two weeks or something strange like that. As long as it's plugged in, the DC-DC converter of the smart is also charging the 12V-battery.
The US Smart manual only mentions keeping the Smart plugged in at temperatures below -20C. And unfortunately, we have found that the manual does contain errors.

We have a case of a Smart getting its HV battery bricked with a dead 12V battery even though it was kept plugged in to a L2 charging station. We do know that the discharge or removal of the 12V battery seems to cause the HV battery to totally discharge, rendering the car a total loss. Whether it is a bug or feature we don't know.

I know that my DC-DC converter does cut off about a minute after HV battery charging is complete. So, we were thinking that the 12V battery can go dead, then the HV battery pack bricks, even if the car is plugged into a charging station.

But then I coincidentally heard the contactors close for a couple minutes while checking my 12V battery with a ammeter to determine how fast the 12V battery gets discharged while parked* So, plugged for charging or not, the battery pack contractors do seem to periodically close on some schedule to keep the 12V battery charged. I'd like to hook up some kind of datalogging voltmeter to my 12V battery while it is parked for a day or tow to confirm this. But this obviously was not happening on the Smarts of the people were were 12V-dead-and-HV-bricked victims. Our hypothesis is that there is a software update that fixes this bug - but a lot of Smarts did not get the update as it was only a service campaign, not a recall.

By as far as storing the car, my recommended procedure for normal storage in temperatures that no more than briefly go below -25C (-13F) is to:

1. Get the pack SOC down to 70%
2. Hook a battery maintenance-type charger to the 12V battery through the storage period.
3. Don't plug it into a charging station.


That's all you need to do.

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* https://www.smartcarofamerica.com/forums/f170/2-volt-battrey-drain-measurement-154552/
 

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"We have a case of a Smart getting it HV battery bricked with a dead 12V battery even though it was kept plugged in to a L2 charging station. We do know that the discharge or removal of the 12V battery seems to cause the HV battery to totally discharge, rendering the car a total loss. Whether it is a bug or feature we don't know."

THIS! I lost my 2015 because the 12 volt went flat and killed my HV battery, 6 months before my lease end (2.5 year battery life). Smart picked up the last 6 payments... That how I got into my 2018 EQ 453!
 

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I have a 2015 ED coupe with 17K. How do you know when the 12v battery is getting dangerously low? And what happens when you swap to a new battery and it's disconnected for a short time? Is that enough to brick the HV battery?
 

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Good questions - had the same ones myself. First question to you is did you have the one service campaign done that might possibly fix the issue? You can find out by contacting any Mercedes dealership and asking if there are any service campaigns that your car has not had. I just had the campaign done on my coupe. Cabriolet had it done before I bought it.

So I still have some apprehensions. Do I replace my 12v battery before it starts telling me it's weak? How long can I let the car sit with a weak/bad 12v battery? Did the service campaign actually take care of the bricking issue?

Len
2014 EV Coupe 19,000 miles
2014 EV Cabriolet 13,500 miles
 

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Sokoloff said:
did you have the one service campaign done that might possibly fix the issue?



Len

2014 EV Coupe 19,000 miles

2014 EV Cabriolet 13,500 miles
I have no idea. Guess I'll need to find out. Thanks.

Sent from my SM-T580 using Tapatalk
 

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I have a 2015 ED coupe with 17K. How do you know when the 12v battery is getting dangerously low? And what happens when you swap to a new battery and it's disconnected for a short time? Is that enough to brick the HV battery?
No, you can safely swap the battery - probably even take 2-3 days to do it. The time for this hypothesized "suicide mode" to discharge the HV battery pack would have to take at least several days or it would start a fire.

As long as the car turns on when you turn the keyswitch, you are fine. If it doesn't turn on, charge the battery or jump it with another car (don't use those jump-starter packs - they don't work). You can also check the battery voltage with an voltmeter. About 12.5 volts or higher is fine.

Also, we have a few DIY people here who removed and opened their HV battery units and successfully resurrected them by charging them cell-by-cell, with a benchtop DC power supply, carefully, using a specific protocol. But then they get stuck becasue a Mercedes STAR syatem, generally only available at dealers, is needed to reset the syatem and clear all the fatal fault codes that immobilize the car. But, if they take them to a dealer, even if they lie about what they did to their HV batteries, the dealer will refuse to do the reset and will, based on the diagnostics, insist on replacing the $20K battery - if they can get a battery at all.

So basically, it the Smarts ED are being rendered a total loss more by a rigid corporate bureaucracy than anything electronic.
 

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I know that my DC-DC converter does cut off about a minute after HV battery charging is complete. So, we were thinking that the 12V battery can go dead, then the HV battery pack bricks, even if the car is plugged into a charging station.
I need to check that back. Interesting what you are saying.

I will log the next charge of our ED3 and check that.
 
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