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Do you need to do anything special to replace the aux battery in the trunk. I understand its a group 49 that you can purchase at any auto parts store. When you replace it do you need to reset all your convience features??

Thanks
 

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Isn't it much easier to call roadside assistance and have them install the correct battery and reset the systems instead of guessing or screwing things up to save a few bucks. Not in my opinion, but that's up to you.
 

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The battery in the trunk is not a conventional lead acid battery. It is an "Absorbent Glass Mat" battery that may not be available at a typical auto parts store.
 

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The AGM battery in the trunk is made by Varta.. if you are getting the consumers off message at start up this could be because the car is not being used enough.. You can charge them without any problems but the charger must be a fixed rate charger and at 10% of the capacity so in this case it should be 7amps.. they can take along time to charge even at this rate.

They are charged when the battery voltage is back up to 12.5 volt
 

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absorbed glass mat (AGM) battery
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A relatively new type of sealed battery construction that uses saturated absorbent glass (boron silicate) mats between the plates instead of a gelled or liquid electrolyte. AGMs batteries are more expensive than the flooded (liquid) variety but offer a number of advantages.

Since all the electrolyte (acid) in AGM batteries is contained in the glass mats, it can't spill, even if the battery is broken. Being thus non-hazardous, AGM batteries are cheaper to ship. Additionally, since there's no liquid to freeze and expand, they're practically immune from freezing damage.

Nearly all AGM batteries are recombinant, which means that the oxygen and hydrogen recombine inside the battery. Recombinant batteries use gas phase transfer of oxygen to the negative plates to enable recombination back into water while charging, thereby preventing the loss of water through electrolysis. The recombining is typically more than 99% efficient.

The charging voltages are the same as for any standard battery, so there is no need for any special adjustments and no problems with incompatible chargers or charge controls. Since the internal resistance is extremely low, there is almost no heating of the battery even under heavy charge and discharge currents.

AGMs have a very low self-discharge – from 1% to 3% per month is usual. As a result, they can sit in storage for much longer periods without charging than standard batteries.

Even under severe overcharge conditions, hydrogen emission of AGM batteries is far below the 4% maximum specified for aircraft and enclosed spaces. The plates in AGM's are tightly packed and rigidly mounted, and will withstand shock and vibration better than any standard battery.

Even with all the advantages listed above, there's still a place for the standard flooded deep cycle battery. AGMs cost 2 to 3 times as much as flooded batteries of the same capacity. In many installations, where the batteries are set in an area where you don't have to worry about fumes or leakage, a standard or industrial deep cycle is a better economic choice.
 

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Just replaced mine, bought at MB dealership, bit of a pain to get out, with all the surrounding pieces, but take your time, becomes quiet easy. Nothing needed re-setting. Car settings not effected, everything working fine. With MB supplied battery, get 4 year replacement warranty.
 

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Just replaced mine, bought at MB dealership, bit of a pain to get out, with all the surrounding pieces, but take your time, becomes quiet easy. Nothing needed re-setting. Car settings not effected, everything working fine. With MB supplied battery, get 4 year replacement warranty.
I just got "Consumers off line" message on mine SL600. I hope this is because it's been sitting in the garage most of the time.
How much is a new battery?
BJ
 

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I just got "Consumers off line" message on mine SL600. I hope this is because it's been sitting in the garage most of the time.
How much is a new battery?
BJ
Is it the original battery? If it is the message will begin to show up more frequently and it will be time to relace it. I had mine replaced via Roadside assist and it was apprx. $230.
 

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I paid 160 as an employee....no problems, did it in their service drive, and then the automatic door came down on my car....sad day
 
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