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12v battery replacement problem

7372 Views 21 Replies 9 Participants Last post by  DudeInTheSmart
I replaced the 12V battery in my 2014 Smart EV 451. The car didn’t like me doing that. Anyone else had this problem?
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Hmm. If that is the case, pull the service disconnect, then disconnect the neg terminal of the 12 V battery. Let the car sit maybe 30 mins to let any capacitors discharge, reconnect the the 12 V, then the service plug, and hopefully she's happy...

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The point is that we are afraid of what the car's psychopathic gaslighting software will do to the car if it detects the service disconnect being pulled. The service primer refers to the cars syatem being de-energized first with the "DAS system", then the service disconnect is pulled.

No normal, physics-based mechanical or electrical assumptions can be relied on when working on a Smart ED.
My interpretation from what I read was he kept the plug installed, changed the battery, and then got the "you're screwed" message after installing the new one. I figure it wouldn't hurt anymore to try the official route of disconnecting the plug, then simulating changing the battery, in the hopes that the ECU forgives him for not following the official instructions.

It may be a case of misery likes company, 12 V system has a failure and decides to take HV system down with it, and/or vice versa...

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Someone for goodness sake pay the piper the $60 and pull the instructions for this.

Like I noted in another thread no Mercedes in my lifetime required any sort of fancy dance to replace the 12 V battery. BMW, Porsche, even Ford yes, but not Mercedes. Sadly, my suspicion is that something is failing along with the dead 12 V or HV battery. Something that possibly Mercedes/Smart warranty should be covering....

Even if you didn't program the new battery in all three model experience I had with Porsche, BMW, and the Ford the car still started up. It was more for longevity of the battery. Something else is breaking, maybe due to low voltage...

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Available service information states that HV system de-energization, involving among other things, pulling the HV service disconnect, is to be performed for changing the 12V battery. Yes, I know some successfully replaced their 12V batteries without following this procedure, but this does not mean it will always work.
Do you mean different software versions, because I can't see how it would affect different ones differently otherwise? So some are programmed to self destruct while others aren't? Still points to some kind of failure...

Essentially my point is this, empowered with the actual (updated) Mercedes/Smart service literature, we can know whether we or the car is to blame. It's just like the story of a lady (assumedly not knowledgeable in car service) gets ripped off, vs the less likely male, we are being taken advantage of when we don't know the proper procedure. Stories here are along the lines of "I bricked my smart", not "my smart broke down". I turned a maybe $500+ navigation update into a $250 one by getting the instructions and going to the parts department and asking politely if they'd allow me to install it on my own vs pay a technician hourly to babysit as the car downloaded the USB. My friend fearful a star machine was needed to restore his '14 E class after a needed battery change paid over $500, and more recently we swapped that one out in a a parking lot for the cost of the battery alone.

Don't give Smart/Mercedes an excuse to void any responsibility. At least tell them you replaced it properly. Len already changed his successfully just by swapping it out. Why wouldn't it work for others, unless something else went wrong with the car? Saying it may not work for others is begging the question.

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I may just subscribe. I didn't complete my "manual" for the '12 E Class in the household. One day for $60 or 1 week for $160. Usually 1 day is not enough and exhausting to try... If I do I'll search for a '14 VIN and look up the 12 V instructions. Before Smart and Mercedes were on separate websites. I lost my smart in 2017 so I didn't need to pay smarttekinfo ever again, besides the fact I already got my smart manual. If the HV battery drains like that some sort of warning must be in the instructions...

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12 V replacement instructions are in the owners manual. Ran across it in the '15 ED manual. No HV service disconnect mentioned.

Regarding care for the HV battery:

Don't leave it discharged or almost completely discharged for 14 days or longer, or was it over 14 days? Otherwise might be permanently damaged. Try not to charge it at 80% or higher, nor let it drop below 20% before recharging.

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