I finally got tired of my consumer battery being weak so I replaced it today. My Escort radar detector would always shut down after start with a "low voltage" message, and if it's cold, I'd have the secondary consumers offline for the first 10 minutes or so. I've had very good results with the Advance Auto platinum AMG batteries, and they have a 20% off coupon for orders over $50. it works for store-pickup online orders, so that's what I did. After sales tax and a credit for returning the core, it was about $150. When I went to the store, the guy said he could not install it since MBZ and BMW require special coding after installing new batteries. I know BMW does need a charging system reset, but MBZ does not - it self-adapts. Of course there always the ESP reset and window resync, but that's nothing. He really discouraged me from doing this, giving me a story about how a guy in a BMW lost his instrument cluster functionality. Being properly warned, I took 5 minutes and changed it myself in their parking lot. All is well - no blown electronics.

 

There's a device called a memory saver, like the one below, that plugs into the OBD port and connects to another 12V source to keep voltage to the electronics. Not sure how that would work for our cars, but it doesn't sound like you needed it. Any advice or tips to changing it?



Schumacher (OBD-L) OBDII Memory Saver Detector

 

Rudeney, did the same thing a month ago with no problems.

One thing I noticed when I removed the old battery was that it was a Non-AGM battery. The idiots that I bought the car from put in the wrong battery.

Now I don't have to put it on a charger anymore.

 

I would not use a battery saver on these cars. The SAMs are just too sensitive. IT took me less than a minute to reset the steering angle sensor and windows. Oh, and the radio loses the bass/treble settings (but not presets). I did get a brief low charging voltage and red battery icon, but that went away as soon as I slightly increased engine RPM. I assume the BCM has some logic in current draw and need to self-adjust (unlike BMWs that need coding).

 

I am about to replace the consumer battery in my 2011 sl550. questions: do I have to disconnect the starter battery to replace the consumer battery? did the battery you purchased from advance auto parts store have the port to hook up the discharge tube, and which battery did you get? Do I need to have radio code, will it go out if battery is disconnected, or just the windows and esp need to be reset or synched? This is the first mb ive owned, so not real familar with all the quirks. Consumer battery appears to be original battery by the date code on the battery post. I prefer not to use the battery saver to keep voltage going to accessories if at all possible, as I have read they are not reliable and can cause more problems than they are worth.

 

I got mine from Batteries Plus--best price and longest warranty. And no core charge so I put the old battery in my truck and it is still working great as a cranking battery !

 

No, you do not. In fact, proper procedure is to disconnect the consumer battery first before disconnecting the starter battery, so just replacing the consumer battery m you do nothing with the starter battery.

Yes.

This one: https://shop.advanceautoparts.com/p/...=car+batteries

You radio is married to the VIN, so no code will be needed. You may need to reset the windows and ESP steering angle sensor. Also, you may get a brief red battery warning icon on the MFD, but it should go away after a few minutes of driving.

If you don't drive it every day, you very well may need a battery tender. This car's electrical demands pushes the limits of a 12v system.

 

I do like the Batteries Plus stores - I've gotten very good service from them on other needs. I just checked and they show the Group 48 battery for $194, plus a $12 core charge, less a $10 rebate, and you get 10% off if you order online for store pickup. There's has a 4-year full replacement warranty. Advance Auto is $177, a $22 core charge, less 20% for online orders with store pickup, and it has a 3-year full-replacement warranty. All things considered, I'd probably choose Batteries Plus. It would cost a few dollars more, but the extra year's warranty is worth it.

 

Interestingly enough, I've had the same good experience with Batteries plus, and the Battery I just replaced last month was the Battery Plus Group 48. It had a mfg sticker of 2006, so 11 years in service proves it to be a quality unit. The manager at Advance Auto Parts was a former Battery Plus employee and he was a bit suspect that the Battery Plus Battery I was dropping off as a core was bad. He said that he often tests AGM cores and they rarely turn up as bad. He tried to convince me that it was still good and that I didn't need a new battery. I told him that I was comfortable purchasing a new battery since I was having so many "Consumer" warnings and issues, but he did peak my curiosity and I retained the battery and instead returned a core I'd had sitting in the garage for a few years. Advance Auto Parts doesn't have the type of battery tester necessary to check the actual cell status of the batteries, but that employee assured me Battery Plus did. So I took a trip down to Battery Plus a couple weeks later and had them test that battery. Sure enough, it showed cell damage on the depth charge test. So even though a standard battery tester will return a test result of healthy, with an AGM it doesn't provide results for the batteries actual cell state. When a cell is damaged, it'll accept a complete charge, but won't retain that charge nearly as long as it should.

That said, The Advance Auto Platinum AGM solved all the "Consumer" issues I'd been experiencing and thus far has been faultless. So I can happily recommend both it, and the Battery Plus unit, as fine replacements. But other who choose to get their current batteries tested, take note of the above, and make sure to get the cells tested. And two thumbs up to the Advance Auto Employee who was so diligent and honest to have sent me on that little exploratory journey. I'd never had a reason to learn all this otherwise.

 

 

That Pep Boys Battery is a Wet Cell Lead Acid, and the consumer battery should be an AGM Deep Cycle. Since the consumer batery isn't used for starting, the cold cranking amps aren't important. What is important is the ability to sustain continuous deep cycle drains without damaging the battery and AGM's are superior to flooded cell batteries for this purpose. Many have gone the route of the flooded cell replacement and wonder why they keep killing their batteries.

As an addendum, continuous use of a non Deep Cycle Battery for the consumer places excess strain on the Battery Control Module and can hasten their failure. For reference, the replacement cost for a new BCM is in the $1000 range, (labor not incl) <Although you can chance Ebay for a used replacement for about half that, but the point being, any savings made by using an improper consumer battery could then go up in smoke - literally!>


Bosch Group 48 - Pep Boys

 

Aussieduede --there is another battery at pep boys, not the one you show. It is VRLA AGM battery, it has a 4 year warranty and is priced at $199.00. less 20% if ordered on-line. Its a H6/L3/48 GROUP SIZE, and according to the descrition, it has 70 amp hrs, with 760cca, is capable of being vented outside. If you enter vehicle info: 2011 mercedes sl550, it will bring it up. The warranty says 48 LTD warranty. Its the best price I've found, but not sure about the LTD warranty. Unless someone knows what this is, i guess I will just go to the local store and check it out. I was just curious if anyone had used this batttery?

 

 

Thanx for the update. That battery looks to also be a fine replacement for those who are in a market served by Pep Boys. And here is the blurb about the warranty from Pep Boys website. 4 Years full replacement for their AGM Batteries.

 

We only have Pep Boys tire stores here and I don't think they sell batteries. But if they did, I would not buy from them. I had a huge problem with them when I put tires on the C240. I got a great deal on a set of Hankooks with the extra warranties, etc. for about $500. Literally one week after that, the kid hit a pothole and blew out a tire. No worries, though, I had road hazard and all that so I told her to take it in. She called me from the store because they told her the tire would cost $70! I got on the phone and the guy told me it was the pro-rated road hazard warranty, plus all new fees for disposal, taxes, mount and balance. After much argument about how the tire had maybe 200 miles on it and that I had paid for lifetime everything, he kept arguing. He eventual agreed to pay for the tire, but made us pay half the M&B and the disposal fee, so it was $20 I think. I escalated my complaint about this to regional manager who told me that's the way they do it. I even wrote a letter to the president of Pep Boys and got crickets. No more Pep Boys for me! I'll stick with Costco.

 

question on the battery install. Everything says battery is vented to the outside. I see where the elbow and line go into the battery. After market batteries at Advance auto and Batteries plus have vent hole on both ends of the battery. the existing elbow and fitting go into the end at the positive post, but what about the vent hole on the end near the negaive post, does it have to be plugged. I notice on the original equipment battery (havent taken it out yet), there appears to be an orange plug in the vent hole in the oe battery. does this plug come out and can it be put in the replacement battery?

 

Being a new mercedes owner, I really appreciate all the helpful comments. Today, I finally decided to replace the battery in the trunk of my sl155. I bought it at Adbance Auto. Got a great price, 25% off. Only has a 3 year warranty, but I dont see that as a negative as the OE battery lasted 7 years, and if I chose to use a battery maintainer, it probably would have gone on for quite some time, but I didnt want to take the chance, so I replaced it. I installed it myself and had no difficulties. After installing, I turned the steering wheel lock to lock, SR light went out, no other lights ever came on. Synched the windows and all is good, took about 15 minutes. Used factory installed vent system, and took plug out of the OE battery to plug the other vent hole at the negative post of the new battery. Now wondering if I need to use a battery tender, as I will not be driving the MB much during winter months, but will in the spring and summer, and if so, are there special tenders recommended for MB?? Thanks again to all. I will be a regular visitor to this forum to keep my sl550 in top shape, as it only has 36k miles now and is in great condition. I did pay to have the thermostat replaced, and that was quite a shock. I could have and should have replaced it myself, but was a little afraid of the MB quirks and didnt want to screw something up this soon after buying the car.

 

You ill want a battery tender for the winter months. And the thermostat on the SL550 is not a difficult DIY job, but the part is more expensive, so don't fret on that repair cost.

 

The guys on forum posted that the battery charger/tender that MB sells at dealerships are CTEK rebranded. Quite a difference in price, considering you're buying same exactly chargers. Bought mine a while ago, don't remember the exact model - very happy about it. It is a charger/tender combo, kept connected for days so far without disconnecting the battery or closing the trunk. Has a fuse too - quite surprised where they located it - on the cable, didn't go deep into what's exactly for - saving the battery or charger 😅. If you'll make some research it will be easy to figure out which to buy. Just make sure you pump the tire pressure up a little during winter storage. I bought also a car cover to keep it clean. After that you can be a happy camper just like me 😊

Regards.

 

What component(s) on the car are actually doing the slow drain of the battery? Anyone know?

 

Rudeney might know 😁

 

I think the biggest draw is SBC. Anytime the CAN bus wakes up, it check the pressure on he SBC system and if it's low, it pressurizes it. Opening the trunk or a door triggers a CAN wake-up and thus may operate the SBC pump. The pneumatic system is another consumer that's active because it controls the trunk latch and door locks. If there are any leaks, the PSE pump cycles to keep a vacuum pulled on the system. On top of that are the "usual" consumers like the clock, KeylessGo, RCL, etc. It's just enough that a weak battery, adverse climate, and a few days of garaging can cause a power drain.

 

And if I remember correctly it does not go in sleep mode if you don't drive the car past certain number of days, it just doesn't have a function like that.

question: are 2 weeks of charge for the rear battery considered on the low end of range, thus old battery? Or average, so I could use it couple more years?

Regards

 

Are you saying that your battery discharges after two weeks? If it takes that long, I;d say it's in pretty good shape. Most will be low just sitting for a few days.

 

Yes, if don't drive it for about 2 weeks I get the "conveniences temporarily unavailable" message. Was wondering because didn't really check on the batteries since I bought the car. And even if I live in California I don't get much sun in the winter