justanick

Hi all,

Recently my car’s (C class C250) eco start stop is showing amber colour @ sign on my dashboard. The green eco sign only comes once in a blue moon.
My Mercedes Benz quoted main battery responsible for this with a $1000 quote and said the software also needs to be updated with the main battery change.
I called Battery world they said they have stock of original MB battery and it’s around $650 but would like to see the car’s battery.

MB dealer tested the battery and it was around 12.26V.

Questions:
1) Is it time to change my battery now and is eco start stop really does save fuel?
2) Shall I change the battery through battery world or Mercedes? I am not sure why a software update is needed for a battery replacement.

PaulR7

Start stop and changing the battery is debatable. I have changed mine since it wouldn't really hold charge (11.6-11.7V the next day after being parked up overnight) however the car still started up just fine every time, it was only the start stop that didn't work.
The start stop system does in theory save some fuel (not very significant amount in my opinion) but it also puts more stress on the engine in the same theory.

If you do go ahead with changing the battery I'd go ahead and order one somewhere online (I've used Varta F21, the exact same battery as OEM MB without the MB branding) which was only around £140 and fit it yourself which comes in well under the budgets you provided, I haven't coded it in and didn't have any problems however you can still get MB/MB specific indy to code it for probably half/hour of their rate if it does give you issues.

Ron P Baker

My Start/Stop and Hold feature recently quit working. I did get the "Auxiliary Battery Malfunction" warning at start up. The dealership replaced my "auxiliary battery" which is actually a capacitor/voltage regulator however my Start/Stop still wouldn't work until my 6year old OEM main battery was replaced.

I confirmed this because when the service advisor called me to tell me my main battery had failed testing and they would replace it for $530, lol I declined. When I picked up my car the service advisor reminded my Start/Stop would not work until main battery was replaced, and in fact it did not function until I replaced it (Pep Boys $225 - exceeded OEM stats - no software needed)

justanick

I searched online and the info I found is 1) after the battery is changed the coding needs to be reset so that it gets picked up in the next servicing 2) no coding required and it’s a lie from dealership
Now I’m confused. I called Autobarn and battery world in Sydney and they don’t do anything with the coding not aware of it.

also for 12.26V how long can my battery last until replacement? I only do city driving.
start stop was silly to begin with but now that I don’t have it I’m just paranoid.

PaulR7

Only doing city driving probably doesn't help, if the battery is around the 12.2V mark after being left overnight then I'd say this battery should still be good for a year or a couple.
As for coding the battery it's better to tell these newer cars that a new battery has been fitted so they can be charged properly rather than being overcharged (and hence their lifespan shortened) by an overcompensating alternator thinking the battery is X years old.
Maybe get into the habit of hooking the car up to a trickle charger over the weekend, this should let you prolong the battery life especially with your city only driving.

justanick

Thanks again for your reply. What’s a trickle charger? I live in an apartment and park with other cars in carport. Leaving the charger with hood open over the weekend might not be a great idea.
so 12.26V after not driving over 2-3 days should be good, right?

PaulR7

I used to use NOCO genius 5 (still do but got rid of my W205), the cables are thin enough where I could run the whole unit in inside the passenger door with some clever mains cable routing to the back of the door and then run the actual charging cables through the door by the A pillar, under the hood (bonnet) and have everything shut including the door and the hood. I didn't take any pictures before I moved on from the car however I've tried my best to depict it on images found on google. With this setup the only possible problem for you would be getting the power close enough to the car.
Red is the mains lead, orange is the device itself and blue are the positive and negative leads that would clamp onto the jump start point and a ground bolt inside the engine bay.

justanick

Thanks a lot mate.
so if I buy this battery charger can I lift the 12.26V to a higher charge?

PaulR7

Most likely yes, you might even get the start stop function working again though it won't bring a dead battery back to life but it sounds like yours still has quite a bit of life left in it.

DYC300

Could someone please help me understand under what conditions the "amber" colored "A" is present on the dash?

I assume that the "green" colored "A" is present when the car is stopped via start/stop functionality (at a red light and when the car is warmed up, for example). But when does it go from "green" to "amber"?

I'm trying to figure out if the "amber" pops up when you manually turn off eco start/stop via the center console button OR when the functionality disengages because the car is in motion OR when the vehicle cannot engage start/stop due to a condition, such as low battery voltage.

My eco start stop functionality stopped working ~December 2021 and I don't have any "A" symbol on my dash whatsoever.

Gazwould

Stop Strain is the biggest con ever .

Too many prerequisites and any tiny fuel saving will be greatly offset by higher maintenance costs caused by Stop Strain .

Then there's some trying to fix the abomination by replacing both main and auxiliary at great cost and still no SS abomination .

Here's my original battery tested 1.5 year ago.




Guess what....

No problem starting the car .

GJC400

I had a low battery but didn't know it because the car started fine (2015 C400). I experienced the start/stop no longer functioning (a plus in my book). However, at the drag strip my car was significantly underperforming. My jb4 logs were all over the place and the car was no longer boosting consistently, nor was I getting anywhere near what boost levels should be. I read somewhere online that a low main battery might impact sensor function, so I replaced it outright (bought for $250, installed it myself). All of the problems were solved in 15 minutes. Seriously, night and day. I confirmed this with jb4 logs, as well. Our cars do, indeed, need a strong battery to run optimally. If you have the ability, I would strongly suggested replacing it instead of continuing to try to keep it topped up with a trickle charger. Even if it starts, and even if the alternator is charging correctly (mine was), your computer may be doing gymnastics in the background. This is my $.02, of course.