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I think you've hit the nail on the head twice.

MB should not be allowed to declare that their battery pack is a $10K black box that they have no responsibility to fix inherent problems with. Even if you get a "new" one, it still has the same problem as the one it replaces. Do we know if the 453 pack has the same problem yet?

The pack must be draining itself, which is an inherent design flaw - current Li-Ion batteries take a very long time to self discharge if left alone. It may be draining itself to charge a faulty 12V battery, but as you pointed out, completely removing the 12V battery didn't stop the pack from bricking, so the BMS or something else in the pack is discharging it, with NO safety mechanism to stop it. That is a massive design flaw that MB has managed so far to avoid responsibility for.

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But based on what I think you wrote, one problem is that in many (or all?) of these cases of failure, when the battery pack is opened, the cells are found to be discharged to not just 3 volts, but to near zero volts. (30 volts for the whole pack in the cases I've read about). So the cells are being discharged to zero by the BMS, triggered by some event. In one of these cases, the 12V battery was removed from the car for the winter, so the pack was not discharged because the DC-DC converter was trying to charge the 12V battery. Also, an excessively low state of charge should not cause a lithium cell to discharge itself to zero - the cell will just sit at that low state of charge indefinitely.

Since the subject of this thread is the responsibility of Mercedes Benz for this problem, why are THEY not addressing this problem? Is is not like MB has gone out of business (like some early EV manufacturers did like bug-laden Think EV or the Vectrix or Current scooters). We should not have to rely on amateur tinkerers to come up with a solution.
 

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Discussion Starter #82
I think you've hit the nail on the head twice.

MB should not be allowed to declare that their battery pack is a $10K black box that they have no responsibility to fix inherent problems with. Even if you get a "new" one, it still has the same problem as the one it replaces. Do we know if the 453 pack has the same problem yet?

The pack must be draining itself, which is an inherent design flaw - current Li-Ion batteries take a very long time to self discharge if left alone. It may be draining itself to charge a faulty 12V battery, but as you pointed out, completely removing the 12V battery didn't stop the pack from bricking, so the BMS or something else in the pack is discharging it, with NO safety mechanism to stop it. That is a massive design flaw that MB has managed so far to avoid responsibility for.

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Thanks. With this problem, and the Volkswagen emissions control scandal before that, my opinion of both German engineering and German corporate ("GmbH") business culture has gone way downhill.
 

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In one of these cases, the 12V battery was removed from the car for the winter, so the pack was not discharged because the DC-DC converter was trying to charge the 12V battery. [Yinzer]
To clarify: "so the pack would not be discharged". Is that a bit clearer?

Who removed the 12v batt as a preventative? I haven't seen that anyone claims to have actually done that. I have proposed doing so as a logical response to hv batt destruction, but have yet to try it myself.

Technical German is very difficult; Schiller's poetry much easier for me back when. Google Translate is indeed totally goofy!
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Discussion Starter #84
To clarify: "so the pack would not be discharged". Is that a bit clearer?

Who removed the 12v batt as a preventative? I haven't seen that anyone claims to have actually done that. I have proposed doing so as a logical response to hv batt destruction, but have yet to try it myself.

Technical German is very difficult; Schiller's poetry much easier for me back when. Google Translate is indeed totally goofy!
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A guy in Canada with the handle "Brucesmart" did it and his Smart was bricked in the spring. He made a heroic effort to rejuvenate it to no avail. Taking the battery out and into a heated space is SOP in cold climates for IC cars that are not going to be used in winter to keep the battery from freezing (which it does very easily if it gets a bit discharged). I've had it happen to me in even a milder climate. A less healthy cell will freeze and swell and ruin the whole battery.

And yes, Google Translate does a better job translating Korean or Japanese into English than German into English. Odd, considering English is supposed to be a "germanic" language.
 

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As I mentioned in an earlier post my 12v batt died and the HV battery bricked itself (yet another smart car COVID 19 shutdown victim). Yesterday I removed the battery and started charging with a lab supply but I noticed one cell was a dead short (5mV while all other cells were 1.5V)

Question: does the 451 HV BMS have the capability to shunt around a bad cell or is the pack ruined if one cell goes bad?

thanks!
m-
 

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The mistake he made, given that Smart_EVs play by their own rules, was to not show up at least every 2 weeks, lets say, to check both batteries in the car being 'stored'.

I suggest not to use the term 'bricked' routinely but only for packs that are unrecoverable (all 90+ cells). MB may consider them to be 'bricked' for their own design failure and servicing incompetence but we know well that cells in the hv pack are recoverable when carefully charged on an individual basis. A procedure that a properly designed charger module would render completely unnecessary (as in Tesla, Chevy, Nissan, Hyundai, Kia, ie the rest of the EV industry). MB simply refuses to embrace industry standards (as established mid-2012) for their 451 series cars. Furthermore MB should sell owners individual replacement cells when owners are paying specialists to 'repair' their failed Smart power packs.
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MB simply refuses to embrace industry standards (as established mid-2012) for their 451 series cars.

Furthermore MB should sell owners individual replacement cells when owners are paying specialists to 'repair' their failed Smart power packs.
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“Industry Standards” citation?

Doubt that Daimler will ever sell individual cells over the parts counter. The Daimler attorney’s no doubt would see the potential for huge liability claims!
 

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The only Tesla that allows the battery to 'brick' was the Roadster (2008-2011). All other models cut off the hv batt at a safe level to avoid damage (similar to what a cellphone does). I have tested this on my 2012 ModelS which sat untouched for 2.5 years and then routinely charged up to the same original 265 miles range when we finally plugged it in. And of course the 12v batt died at some point during this period but this did not affect the hv batt at all.

Chevy Spark/Volt/Bolt does likewise, at least I've never heard of one bricking thru normal neglect. I own three 2014 Spark_EVs: one daily driver with 52kmi, one salvage low miles (no airbags deployed), and another salvage (a/b deployed). All three have good hv batts that live happily for months on end, if necessary, not being plugged in at all. When I want to up the %charge I just plug them in for a while. And all three have not required the presence of a 12v battery for the hv pack to survive.

So since the Tesla Roadster stopped being produced in 2011 there has been this 'Industry Standard' of well behaved hv batts, I didn't make this up, this is EV reality. And you choose to doubt this and defend MB's incompetency. Do you plan to sign this petition?
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