droptail

Any unique procedure or requirement in changing the main battery - particularly as it relates to the computer?

crconsulting

This is a good thread on the subject:
https://mbworld.org/forums/sl-class-...ent-guide.html


Good Luck.

SteveL1

If you are a member of AAA, they will come to your house and replace it for what it will cost to buy a good battery. No fuss no muss.

ThatsMyDawg

There is nothing special about changing the battery. 15 minute of work and nothing to adjust, etc. with your computer..
You will be fine....

ZCARGUY

Replaced mine last month. Easy. Just make sure to vent the battery and plug the other side.

Best price: COSTCO.

Baltistyle

The trick in ease of battery change is to use the same style of battery chemistry so the digital charging system works correctly. The bcm has different settings (rate of charge) and needs to be set for the right style. No change, no worries.

droptail

Thanks guys for the response. I heard "somewhere" that the ecu had to be reprogrammed to ta new battery is why I ask.
Got an AGM replacement at Costco, but had some weird behavior after. The trunk wouldn't stay closed - it would re-open, and the remote wouldn't work as well as the door handle lock & unlock. Then it started to work.
Also I scanned the computer & it shows like 8 faults, like both heated outside mirrors shorting, entertainment center prob...

droptail

Thanks, I found this before but no mention of the computer or possible issues.

Baltistyle

IMHO, I think this is why there were electrical fires and issues on so many early merc that had the bcm’s. Nobody knew back then.

If you have star, it’s easy enough to change. Don’t burn your car or house down.

crconsulting

You’re confusing the R230 BCM issues with the R231, which has different BCM circuitry and no such issues.

crconsulting

Definitely one of my favorite lines 😀
The only remote chance of having to hook up XENTRY is if you leave the car without a battery for a very extended period of time. And the rear SAM is what controls the charging cycles to battery/BCM.
Sounds like what happened there is the COSTCO tech probably took the battery out and went to lunch. Then came back an hour later and hooked up your new battery. If you know how to access the engineering mode in your in dash NTG 4 display. There will be an error stored there too. You’re car was probably “relearning”

Here’s the bottom line:
Dozens of R231 forum members have successfully removed and replaced their AGM main and Auxiliary batteries with no issues. As always, if you’re hesitant that this is outside your comfort level, don’t hesitate to get it done at a shop. But I guarantee you probably are a more skilled mechanic than the tech at COSTCO that swapped your battery out. 😉

Good Luck

Baltistyle

Yes I know this was with the earlier Sl’s hence my saying older mercs with bcm. In that it was upgraded my assumption was there would still be settings for different battery chemistries vs an automatic read because even my newer higher end digital battery charger asks for the type of battery. How would the car know if there’s no computer communication with the battery itself.

Happy to learn.

crconsulting

The above statements maybe need clarification but there is a battery specification that must be adhered to. There is the MB part number in the thread I linked to initially. There's lots of good info and some screen shots I posted of how the rear SAM behaves and tracks charging. The battery "chemistry" for these batteries is a constant. You shouldn't swap AGM's for a different types of battery. I have found the MB batteries to last the longest but thats my experience and preference.
That correlation seemed somewhat unclear as how it applies to the R231, hence why the clarification. People sometimes get the two confused.
There have been no "spontaneous combustion" instances that I have seen reported for the R231's. The charging system hardware, and it's behavior differ in several ways.

The above question may need clarification but,
I believe what you're thinking of, is how the charge cycles are tracked and controlled by the rear SAM (see thread I initially linked to). Technically, it monitors the batteries and it's condition, and charges it appropriately. It does have a learning cycle, but should adapt after the car is driven. People also have problems with cars that sit because they never adapt to the new battery. Clearing that SAM data probably won't help either, as the cars need to be driven to learn the "adaptation" for the charging system.

droptail

I changed the AGM Costco battery myself - I don't usually let anybody work on my vehicles. Everything seems OK when I took it out today.
Overly complicated as I was warned.
Thanks

RonNSoCal

My seven year old 2016 battery needs replacing according to my independent mechanic. He is recommending that I have him get one from MB and let him install and match to charging system and erase codes that he expects will be thrown in the process. He estimates about $350 but I will know more once he gets a price on the battery.

ThatsMyDawg

Do it yourself.
There are no codes to be thrown
There is nothing hard about it.
Either buy the battery from MB yourself or simply ask them what is the part number for the battery and then go purchase one on your own.

rmorin49

I seriously doubt Mercedes has " unique" main batteries. Get the specs from your owners manual and go shopping. There are only a few battery manufacturers in the US. I suspect the MB branded battery is made by Bosch or their supplier.