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Discussion Starter #1
Was wondering if Aux battery will keep the MCU and all the memory setting while I change my main battery.
Just got a new one and according to sales rep I need to have it installed at certified mechanic which seems like they just want to protect themselves from any related problems.
I'm hoping my Aux battery currently at 186CCa/200CCA at 13.16V would hole the settings for a quick swap or should I connect jumper cables to another car to be safe? Swap the battery while engine running?

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What memory setting are you worried about losing? Your driving style will be relearned after during hundred or so miles. Other system settings you have created will be saved.
 

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Discussion Starter #3
First of all I'm afraid of tripping any codes, could that not be the case at all? Like I said, store had a clear policy hardcoded into their system to let customer know that they can't install it on premises but that mechanic shop service is needed. Why would they do it for other cars not for Merc?
Other than that just memory seats setting I guess, radio and clock haha ;)
 

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Discussion Starter #4
I was also thinking I could disconnect the Aux battery and use that as a backup with jumper cables for few minutes !?
 

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I've had one of those 9V battery-cigar lighter socket cables kicking around in my toolbox for years but haven't tried it on the Benz. They're made to maintain enough power in the system to retain such settings; note that it must be used in a continuous source 12V socket and not a switched. But again have not tried it on the GLA.

But as gbarringer suggests it's not bad to periodically have the system relearn. Consider it a PC cold boot. Any firmware-resident settings will be maintained.
 

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I've had one of those 9V battery-cigar lighter socket cables kicking around in my toolbox for years but haven't tried it on the Benz. They're made to maintain enough power in the system to retain such settings; note that it must be used in a continuous source 12V socket and not a switched. But again have not tried it on the GLA.

But as gbarringer suggests it's not bad to periodically have the system relearn. Consider it a PC cold boot. Any firmware-resident settings will be maintained.
The GLA lighter socket is on the switch. You would need the switch on for it to back feed the systems of the car from the 9V battery. I would not have the switch on when disconnecting the main battery or connecting a battery. You might have a power surge that could do damage as the switch is on and everything would power-up, and if you have a bad hook up and not steady power with a jump from 9v to 12v. Do not believe that you will have any problem with just changing the battery without having power from another source. On other MB forms see people changing batteries as DIY with no problems. The only problem would be you hook it up wrong with poles reverse or wrong order of connections. Neg first in removing and neg last when install.
 
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Ah... I see you're an electron flow vs. conventional current guy, as am I (negative pole attachment first off, last on). (y)

And yes, as I said you have to use a continuous source socket and not a switched for one of the 9V retention batteries. Thanks for the switched-socket insight on the cigar lighter.

The GLA lighter socket is on the switch. You would need the switch on for it to back feed the systems of the car from the 9V battery. I would not have the switch on when disconnecting the main battery or connecting a battery. You might have a power surge that could do damage as the switch is on and everything would power-up, and if you have a bad hook up and not steady power with a jump from 9v to 12v. Do not believe that you will have any problem with just changing the battery without having power from another source. On other MB forms see people changing batteries as DIY with no problems. The only problem would be you hook it up wrong with poles reverse or wrong order of connections. Neg first in removing and neg last when install.
 

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Discussion Starter #8
Thanks for the insights! Glad I asked my questions here and hope this will help many people down the road.
 
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