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I'm hoping to get some advice on installing a new starter battery.
My original is going on 6 years, and although I'm not having problems, I want to be ready when the time comes.
Is it okay to connect an external 12-volt battery to the Jump Start connections under the hood--to retain vehicle settings--while removing the old and installing a new starter battery?
It's my understanding that "registering" the new battery to the vehicle facilitates battery health monitoring and adjusts charging as the battery ages. Is it really necessary to register the new battery and, if so, what are the consequences of not registering?
Thanks in advance for your help.
Last edited by hornethandler; Dec 24, 2024 at 11:40 AM.
I am in the same situation. My car is on a CTEK anytime it is parked. No signs the battery is weak. CTEK goes through the cycle to a green light in a few hours.
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Originally Posted by hornethandler
I'm hoping to get some advice on installing a new starter battery.
My original is going on 6 years, and although I'm not having problems, I want to be ready when the time comes.
Is it okay to connect an external 12-volt battery to the Jump Start connections under the hood--to retain vehicle settings--while removing the old and installing a new starter battery?
It's my understanding that "registering" the new battery to the vehicle facilitates battery health monitoring and adjusts charging as the battery ages. Is it really necessary to register the new battery and, if so, what are the consequences of not registering?
Thanks in advance for your help.
1. I have swapped out both my batteries without ever using a settings retainer and the biggest problem was recalibrating the side windows. If you have a copy of WIS, I would look it up.
2. I know some Mercedes-specific scan tools (i.e., LAUNCH Creader) will perform battery registration. XENTRY should, as well.
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
WIS makes no suggestion to keep the memory active. As a matter of fact, it explicitly states to ensure the electrical system is NOT active. Please see attached documents.
WIS makes no suggestion to keep the memory active. As a matter of fact, it explicitly states to ensure the electrical system is NOT active. Please see attached documents.
Thanks Jetta.
Is there any mention of battery registration/coding?
I never understood why changing a battery mandates recalibrating the windows, except that it encourages folks to visit their dealer for a new battery. I've replaced several batteries in the past 5 years, and use my Noco charger's 12V setting and OBD powering accessory connector (intended for this purpose) to keep the car's settings from being wiped out. Battery registration? The newest form of window recalibration. Even a freshman EE student can identify which of 2 batteries is aged and which is new, but an intelligent battery controller can't? The WIS documents advise using a suitable container for pouring battery acid into. Not owning a suitable container, I return the battery to the auto store still filled. What's everyone else do?
I recently replaced the alternator on my SL and the battery was disconnected for a couple of weeks. When I reconnected nothing was lost. I think it resets the adaptation to your driving style, but that's no big deal. It quickly readapts.
Don't know if it's critical, but I like to let the system go to sleep before I pull the negative battery cable. Open the trunk and hood and then let it sit for 10 minutes or so until the trunk lights go off.
I recently replaced the alternator on my SL and the battery was disconnected for a couple of weeks. When I reconnected nothing was lost. I think it resets the adaptation to your driving style, but that's no big deal. It quickly readapts.
Don't know if it's critical, but I like to let the system go to sleep before I pull the negative battery cable. Open the trunk and hood and then let it sit for 10 minutes or so until the trunk lights go off.
Thanks for weighing in, Joe.
Anything on whether registration/coding is required for the new battery?
Thanks for weighing in, Joe.
Anything on whether registration/coding is required for the new battery?
I have a 2014 SL and a 2018 S. Neither of those required registration or coding after changing the battery. It's possible it's necessary on some of the newer hybrid models, but I'm not sure. I have Xentry and I have never seen any option to do that for my vehicles.
I have a 2014 SL and a 2018 S. Neither of those required registration or coding after changing the battery. It's possible it's necessary on some of the newer hybrid models, but I'm not sure. I have Xentry and I have never seen any option to do that for my vehicles.
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Originally Posted by streborx
I never understood why changing a battery mandates recalibrating the windows...
Recalibrating the windows is simply resetting the auto-stop feature. It's been the same for any car I've owned with power windows. It usually happens whenever there is no power source. In our cars, it is stated to ensure there is no electrical activity when replacing the ECO Start/Stop battery (a.k.a., "additional battery"), so disconnect the trunk batter if needed. Check the documents.
Resetting or recalibrating the windows is an owner/operator task. No need to go to the dealer. Roll the window all the way up and hold the window switch for a few seconds, release and pull up again for a few seconds. Then, roll the window down and hold for a few seconds, release and hold down for a few more seconds. Now the windows should automatically open and close with one touch.
No calibration or learning for charging system is required for battery replacement. You can use a memory saver as mentioned above, but there’s really no issues if you choose not to, other than resetting your pre-sets
If Jetta post the WIS it should mention the memory saver but that should be about it….
Recalibrating the windows is simply resetting the auto-stop feature. It's been the same for any car I've owned with power windows. It usually happens whenever there is no power source. In our cars, it is stated to ensure there is no electrical activity when replacing the ECO Start/Stop battery (a.k.a., "additional battery"), so disconnect the trunk batter if needed. Check the documents.
Resetting or recalibrating the windows is an owner/operator task. No need to go to the dealer. Roll the window all the way up and hold the window switch for a few seconds, release and pull up again for a few seconds. Then, roll the window down and hold for a few seconds, release and hold down for a few more seconds. Now the windows should automatically open and close with one touch.
Jetta, would you mind clarifying: " it is stated to ensure there is no electrical activity when replacing the ECO Start/Stop battery (a.k.a., "additional battery"), so disconnect the trunk batter if needed.
I couldn't find that reference in the doc. you provided on the additional battery installation.
Last edited by hornethandler; Dec 26, 2024 at 10:14 AM.
Thanks for your help, everyone.
My batteries are original and coming up on 6 years old, so I'll be keeping an eye on them.
I just ordered this battery tester. It's entry level, but price and reviews were pretty good.
As the video shows, measuring voltage isn't a reliable method for troubleshooting batteries.
Resistance testing is first step in properly diagnosing these cars….
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Originally Posted by hornethandler
Jetta, would you mind clarifying: " it is stated to ensure there is no electrical activity when replacing the ECO Start/Stop battery (a.k.a., "additional battery"), so disconnect the trunk batter if needed.
I couldn't find that reference in the doc. you provided on the additional battery installation.
This is from AR54.10-P-0007RK. You need to interpret what it says. When replacing the on-board electrical system battery (i.e., big one in trunk), you of course have to disconnect it (see AR54.10-P-0005RK).
In either case, there is a complete disconnect of electrical supply. Personally, as temperamental as these cars are, I would follow what the WIS says and deal with any resets.
On a sidenote, it seems that the Mercedes dealers' prices are reasonable for new batteries. I don't know personally, but I think it would be worth checking if you are concerned about losing settings, etc.
By the way, the same documents pop up for your 2019 model.
.
Last edited by JettaRed; Dec 26, 2024 at 11:04 AM.
This is from AR54.10-P-0007RK. You need to interpret what it says. When replacing the on-board electrical system battery (i.e., big one in trunk), you of course have to disconnect it (see AR54.10-P-0005RK).
In either case, there is a complete disconnect of electrical supply. Personally, as temperamental as these cars are, I would follow what the WIS says and deal with any resets.
On a sidenote, it seems that the Mercedes dealers' prices are reasonable for new batteries. I don't know personally, but I think it would be worth checking if you are concerned about losing settings, etc.
By the way, the same documents pop up for your 2019 model.
.
Thanks Jetta!
I saw that instruction as well when I looked at the doc you provided. I'm not trying to be argumentative, but doesn't that instruction refer to a diode test failure indicating a fault in the electrical system, in which case you are to disconnect the ground cable of the main battery to isolate it from the vehicle electrical system, and then to repair the fault before continuing?
Last edited by hornethandler; Dec 26, 2024 at 11:19 AM.
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
I suspect the "diode test lamp" is something like this used to ensure there is no electrical potential (voltage) in the electrical system. I'm also assuming that the "additional battery" is somehow isolated from the electrical system. When I have time, I will try to read up on exactly how all that works, but for now it seems that disconnecting the main battery is sufficient. That would mean that there is no voltage being supplied from either battery, which also makes me think using some kind of "memory saver" may not be required or recommended.
Personally, I have replaced both my batteries, but don't remember doing it according to the WIS. I may have disconnected the main battery but honestly don't remember. I know there were no major issues after I did it.
I suspect the "diode test lamp" is something like this used to ensure there is no electrical potential (voltage) in the electrical system. I'm also assuming that the "additional battery" is somehow isolated from the electrical system. When I have time, I will try to read up on exactly how all that works, but for now it seems that disconnecting the main battery is sufficient. That would mean that there is no voltage being supplied from either battery, which also makes me think using some kind of "memory saver" may not be required or recommended.
Personally, I have replaced both my batteries, but don't remember doing it according to the WIS. I may have disconnected the main battery but honestly don't remember. I know there were no major issues after I did it.
Jetta,
I suspect you're right that the "diode" tester is simply a 12-volt test lamp used to verify no voltage present at the disconnected ECO battery leads.
If voltage is detected, it would mean there is a connection between the Main and ECO battery.
Jetta,
I suspect you're right that the "diode" tester is simply a 12-volt test lamp used to verify no voltage present at the disconnected ECO battery leads.
If voltage is detected, it would mean there is a connection between the Main and ECO battery.
jmattioni, crconsulting and others have weighed in with some very informative information.
There's a similar instruction when you replace the main battery. After disconnecting the negative cable it tells you to measure for voltage on the positive cable to ground. A voltage reading there means the Eco/Aux battery is not isolated from the system as it should be. There's a solid state relay that connects and disconnects the Eco battery from the system. It's only ever connected to the system when the engine is running and the Eco battery needs charging or during an Eco mode engine restart. I think they include that test because you wouldn't want to accidentally short the positive cable to ground if that relay fault exists.
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