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Help. My vehicle Li-Ion battery went dead - completely dead. I put it on full charge. I was told this would put the battery on full strain. My lead acid battery was also dead so I charged it too and then It would not start so I towed it to the dealership and they say they need to replace the Li-ion Battery for 14K !!! Help. How can charging it to full charge from completly empty after being dead for two weeks cause the battery to fail ?
 

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Sounds like another case of the 12v battery dying and taking out the HV battery. Have several threads in the Electric Drive forum on this subject. There was a service campaign for the 451's that came out in 2016 that might take care of that issue. Did yours have that update? A phone call to your dealer with the VIN should get you that info.

Len
2014 EV Coupe 20,000 miles
2014 EV Cabriolet 17,500 miles
 

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MY08 cabrio MY09 cabrio Brabus MY15 ED
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My lead acid battery was also dead so I charged it too and then It would not start so I towed it to the dealership and they say they need to replace the Li-ion Battery for 14K !!! Help.
Welcome to SCoA.

What indication do you have that the HV battery has been fully charged? What are the messages shown on the dash?

As Len suggests, the HV may be “bricked” for which there seems to be no workaround beyond the $14K dance with the dealer?

Casual reading, nearly 500 posts - EV battery replacement.
 

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Help. My vehicle Li-Ion battery went dead - completely dead. I put it on full charge. I was told this would put the battery on full strain. My lead acid battery was also dead so I charged it too and then It would not start so I towed it to the dealership and they say they need to replace the Li-ion Battery for 14K !!! Help. How can charging it to full charge from completly empty after being dead for two weeks cause the battery to fail ?
Was the car sitting unused for a long period? How long? Did the battery actually charge after it being totally discharged? Normally, in such a condition (voltage below a certain point), charging will be disabled. There is no "full strain" you can put the battery under by charging it.
 

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Discussion Starter #6
Yinzer
It sat for a couple of weeks while waiting for a part from Germany. Jumped the ion battery got it running. Moved the car out of the way. Went to start again battery dead. Jumped the lead battery and it started. Put part on. Vehicle would never start again.
Dealer said replace ion battery!
 

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Discussion Starter #7
Was the car sitting unused for a long period? How long? Did the battery actually charge after it being totally discharged? Normally, in such a condition (voltage below a certain point), charging will be disabled. There is no "full strain" you can put the battery under by charging it.
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Yinzer
It sat for a couple of weeks while waiting for a part from Germany. Jumped the ion battery got it running. Moved the car out of the way. Went to start again battery dead. Jumped the lead battery and it started. Put part on. Vehicle would never start again.
Dealer said replace ion battery!
 

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MY08 cabrio MY09 cabrio Brabus MY15 ED
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It sat for a couple of weeks while waiting for a part from Germany. Jumped the ion battery got it running. Moved the car out of the way. Went to start again battery dead.
What was the nature of your initial problem that required a part from Germany - what part?

How did you "jump" the HIGH VOLTAGE 391V battery?
 

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Yinzer
It sat for a couple of weeks while waiting for a part from Germany. Jumped the ion battery got it running. Moved the car out of the way. Went to start again battery dead. Jumped the lead battery and it started. Put part on. Vehicle would never start again.
Dealer said replace ion battery!
I interpret what you wrote as the car sat parked waiting on a part (what was the part?). Then after sitting for two weeks the car turned on normally, but the state-of-charge SOC gauge read zero, so you plugged it in for charging and it charged (to what SOC?) normally and the car was driven a short distance. But shortly after that, the 12 volt battery suddenly went dead (i.e. car dead and not even the dome light worked), so you charged the 12V battery (or jumped it from another car?) and the car ran again. The part was then installed, but when attempting to drive the car, the car was dead.

Correct?

What kind of service message was displayed?

Unfortunately, the HV battery is treated as a "black box" for dealer service purposes. They are strictly forbidden to open the (rivited shut) battery case. This means that even if just a small inexpensive part in the battery case (current sensor, BMS components, relays) goes bad, the only recourse is to replace the whole battery. However, some intrepid DIYers have opened the battery case and replaced failed parts, reprogrammed the BMS (you can send it to this certain guy's shop in the Ukraine to have it done) and got their Smart ED back running. But for most poeple, this isn't practical. Mercedes Benz does not back their product and have left owners out to dry. I discussed a class action lawsuit but that has not gone anywhere yet.
 

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There is "a rumor" that the battery is not actually damaged, but that this is due to a long-standing software bug.
One rumored approach (I have not done this) is:
1) tie down the brake pedal
2) tow the car slowly for, say 15 minutes
3) check the battery level

The theory is to use regenerative braking to lift the battery up from "too low, I'm broken" up to "I'm just low, charge me up". Again, this is hearsay, but what do you have to lose besides your dignity?
 

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Discussion Starter #11
There is "a rumor" that the battery is not actually damaged, but that this is due to a long-standing software bug.
One rumored approach (I have not done this) is:
1) tie down the brake pedal
2) tow the car slowly for, say 15 minutes
3) check the battery level

The theory is to use regenerative braking to lift the battery up from "too low, I'm broken" up to "I'm just low, charge me up". Again, this is hearsay, but what do you have to lose besides your dignity?

Nipplesultra

Who has tried this successfully? I wonder.
What does it hurt? What about the brakes?
 

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Who has tried this successfully? I wonder.
What does it hurt? What about the brakes?

Don't try it. If the car is immobilized from a battery pack fault, then the regen braking is not going to work either.
 

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Make sure you have the latest software update as mentioned above.

Len
2014 EV Coupe 20,000 miles
2014 EV Cabriolet 17,500 miles
 

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Ah, but that is the point! It's not necessarily a battery pack fault. It may be a software bug causing this nonsense.
By "battery pack fault" I mean the software either by design or by a bug, disables the battery pack by opening its relays and preventing discharging or charging. One does act on anything - be it a car repair or anything else, based on a rumor.
 
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