Stuttgarten

My main battery never exceeds 12.1 volts. It's the OEM unit, not sure how old it is. Are there any good batteries selling with free shipping? I read in Consumer Reports this month that Sears DieHard battery had the best ratings.

cetialpha5

The problem with batteries is that they're heavy and they also have a date code on them. At one point Amazon had a pretty good deal on a battery, but when people got them, they mentioned that the date code was over a year old. Plus if you have a bad battery, it's somewhat problematic if you got it via mail order, how do you intend to return it? So all in all, it's best to just buy one locally and pick one that was recently made. Advance Auto has lots of discount codes, typically takes $50 off a battery. Autozone and Pepboys also have discount codes and you can find the latest ones at retailmetnot. Sears has been slowly going out of business for years, but I guess their batteries still get good ratings and they'll probably still be around for a while yet, there's just never really any good sale there. The voltage on mine varies between 11.5-11.9 depending on how cold it is outside.

kajtek1

PeepBoys had sale on Bosch batteries for about $109.
I believe it is relabeled US-made battery, but hard to beat 90 months warranty.

cetialpha5

That's probably a regular flooded battery. The AGM battery is usually a bit more and that's what MB mostly put in their cars. I would just get an AGM battery. For regular flooded batteries, there's many other places that carry them like Home Depot, Costco etc. I'd just like the AGM because they don't normally vent gases like flooded batteries so you don't end up with any corrosion on the battery terminals and they're supposed to last longer. Although there's some guy out there that likes to go on and on about how some battery from Spain lasted 13 years, but that's not typical.

Stuttgarten

I just checked PepBoys' AGM Bosch, and it's $219 plus installation and additional service fees of $115, but there is a $10 discount plus 20% off coupon. I will definitely go with an AGM, but will shop around first. This thing weighs a ton, and I can't do it myself, so installation is a must!

cetialpha5

Well it's 52 pounds so not quite a ton, but not light either. Advance Auto would install it for free. I think Autozone might too. I think Advance bought Carquest so you could check there too.

kajtek1

Double check the installation. Most of chain suppliers have small print
"Mercedes excluded". The yesterday's burger flippers will have hard time to reset Mercedes after battery replacement.
Than I read reports of such boys connecting battery in reverse and ending with frying $2000 worth of computers.
Flooded battery lasting 13 years is not that rare. I recall at least 2 owners of W210 reporting 15 and 17 years on factory batteries.
So far AGM owners are not coming better than 5 years.
Your money.

cetialpha5

Mine is original and is at 8 years. All you have to do is search the threads, there are many people who have gotten 8-10 years out of their AGM batteries.

There are many articles out there about how AGM batteries are supposed to be better than flooded.

http://www.yuasabatteries.com/faqs.php?action=1&id=32

http://bdbatteries.com/batterycomparison.php

https://www.pepboys.com/car_care_cor...ntages_of_agm/

kajtek1

If you want to educate yourself, you should stop listening to salesmen and start reading some technical opinions.
https://en.wikipedia.org/wiki/VRLA_battery
And again - your money. W211 originally come with flooded batteries. From what the seller told me, the 2004 original battery from my car was replaced in 2013 becouse the car was advertised for sale and several time a day was started for a minute to drive it out the warehouse and then back. That would kill any battery.

Stuttgarten

This evening I had been parked all day, temp was around 58 degrees. I checked voltage and it was 11.9, but when I started car, it went up to 14.0 and stayed around there for my 25 minute drive home. Are these numbers normal?

Is there a date printed somewhere on the OEM battery so I could check it?

mtrevelino

Your numbers should be closer to what is on the attached chart.
Mike T.

kajtek1

Al the cluster readout shows about 0.5V lower than the battery is.
So when 12.4V is normal, but on low side, the 14.5V is overcharge.
I would confirm that with meter on battery clamps.

Stuttgarten

Excellent to have this reference chart. I guess I'm OK.



I agree a visit to AutoZone to check battery is best way to be certain! Thanks.