[Peavey]

I realized yesterday that I needed to replace my consumer battery in my SL 55. After browsing the forums I elected to buy an AGM Duralast battery that was in stock at Autozone. It is listed as an exact fit, but I'm suffering from a little confusion here. The OEM battery is vented and is listed as a VRLM. When I got the Duralast home and looked it over it appears that it is a sealed battery, with no provision for a vent connection.

Am I safe in assuming that this is truly a sealed battery that will emit no gasses from charging, or is this thing still going spell trouble for me down the road?

 

[Gary Knox]

Is the Duralast battery an AGM one? IF not, this battery should be the Absorptive Glass Mat type.

I bought one of these about 10 months ago for my '03 SL55, and it had a vent, with a small rubber tube that connects to a small black 'vent' opening on the top of the battery. The fit wasn't perfect, as the new battery was about 1/16" longer than the MB battery that was in the car. I elongated the hole in the plastic rear hold down clamp so it could move about 1/16" further to the rear on the threaded lug. Fits perfectly, and I keep it maintained with a CTek charger when the car is not being driven. It was about $100 less than MB wanted, and it has a 3 year warranty vs the MB 2 year warranty.

Hope this helps.

 

[Peavey]

Yes, it is an AGM battery - http://www.autozone.com/batteries-s...ry/duralast-platinum-battery/319460_929811_0/

But I don't see any provision for connecting to a vent.

 

[Gary Knox]

In the upper right/rear corner of the battery shown in the Autozone link, there is a small hole. There should be a 90 degree plastic piece that came in a plastic bag, along with a rubber tube. That right angle plastic 'tube' inserts into the hole, and the rubber tube extends from the 'tube' down to the hole at the bottom of the battery box.

IF you did not get the plastic bag, go back to Autozone and ask for it.

 

[Peavey]

Thank you, that makes sense. There are holes at each end of the battery, but they appear to be sealed. Does the vent kit then actually perforate a thin layer at the back of the "hole"?

 

[Gary Knox]

Guess you are going to have to ask the battery guys at Autozone about that!

PS: Yesterday I came across an article of about 120 pages regarding the SL55 written by a Brit. The AMG battery section caught my eye. He states that these batteries do not vent, but if pressure does build up, then the film covering these holes will 'break'. SO - I still think it's a good idea to have the 90 degree angle in the hole and the rubber tube exiting the bottom of the battery chamber. Just in cas -, I don't want H2, or H2SO4 in the trunk!!!