Fellow sl500 owners please help. When I turn on ignition battery icon appears and message about my accessories will not work? Or something of that nature. Car will start no problem but dash info is blank and backup camera not on. What is the problem and how do I resolve?

 

The rear battery is discharged or in its way out. Letting the car sit without running or trickle charging rear battery will drain rear battery. Common problem with these cars, as they get older electrical drains become problematic.

 

so must I replace or recharge? Is it an alternator not charging problem?

 

Replace rear battery in trunk or check if it will take a charge. If the car is not used regularly and or if the battery is too old and will not retain a charge you will get a message stating something similar to "convenience features not available". Try charging the battery first. If that does not work, test the battery and then replace if necessary.

 

I will check and try your suggestions. Thanx

 

What type/size and price battery if I have to replace???

 

Rear battery needs charging or replacing.
I put in mine new battery Varta AGM, works great, it costs around 100$, at MB shop new battery goes like 250$.

 

is it a reliable replacement? where can I get this battery?

 

Well, I can't say it is reliable thing to do. You can get it from any car parts shop, online.
I think it uses size H6.

But firstly, try to charge battery, did you get message after car being left for couple days?

 

no I’ve been driving car. It comes on when first starting, goes away after a restart start

 

I used this for the rear. Wasn't cheap though. About $315!
sourced it from local auto parts store.

 

I would strongly advise not to buy alternative brands of battery, I have tried 3 or 4 over the years such as Varta etc and although good, they never quite hold up as well as the stock standard Mercedes battery. I really would suggest spending a few more bucks and getting the Mercedes Battery and you do not need to run a trickle charge all the time, I leave my car for 6 weeks straight and never have issues with low battery levels. Check that you are getting anything between 13.7V to 14.5V on your alternator.

 

Be happy that your car has no parasitic drain, I have 3 of these cars, and none can be left without a charger, Mercedes battery or not.

 

After driving a bit do those accessories start working? It might take more than a 20-30 minute drive to get the battery up to voltage to restart the accessories.

If the accessories start working again, it should just be the battery. You can try charging it, but if you drive the car regularly and you're having this problem, the battery is probably at end-of-life. You could get the battery tested, but if it's more than 4 years old, I'd probably replace it anyways (your battery might have a small circular sticker on it showing MM/YY of manufacture).

If the accessories don't start working again, then there could be issues with the battery (likely), and/or there could be other issues. Again, you could get it tested, but if it's been going flat for a period of time, that causes accelerated wear on the battery cells, and charging alone won't be able to restore the lost capacity. Once you get a good battery in there, then you need to be on the lookout for parasitic drain.

Consistent with the posts above, I would also recommend a trickle charger if possible to keep the car charged if not driven at least every other day (or for more than 100 miles a week), even on a new battery. It could also help you live with any parasitic drain, but I wouldn't plan to leave the car anywhere for extended periods without a trickle charger. There are many posts about this, but you only need a trickle charger on the rear battery.

The dual-battery system in these cars causes lots of strange issues when the rear battery voltage gets low. Since there is a separate starter battery, the usual signs of a failing battery (slow starts, unable to start) don't occur. Rather, you have a bunch of high drain computer modules that start flaking out. The accessories (like the heated seats) are disabled when the rear battery voltage is low ("accessories unavailable")

 

[QUOTE=cdk4219;8507172]Be happy that your car has no parasitic drain, I have 3 of these cars, and none can be left without a charger, Mercedes battery or not.[/Qa bit having a battery that is gone flats on 3 SLs that you owned has got to be an exception rather than the rule and is really unlucky. Again, this is the whole point that I'm stating avoid buying replacement batteries and get the Mercedes genuine item. I also used to get low battery warnings and had to charge my car with trickle charger, however as soon as I fitted that genuine Mercedes battery I've never had to do this and it's been the same car all along?. I had previously bought two aftermarket batteries and return them both.

 

I believe most people put their r230 on a trickle charger if left for more than 2 weeks. Plus a Mercedes replacement battery only has a 2 year replacement warranty, most agm have 3 year or more.

 

Yes I do see a lot of people using trickle charger, would not be bothered if I only get 2 years from Mercedes warranty instead of 3 years, as the battery should last 7-8 years comfortably anyway so its irrelevant in my opinion, also they will fight their corner when you try and return on car usage etc.