AGM vs Lead-Acid Battery

[nyjam530i]

I Would like the opinion of the board regarding a replacement battery. I have a 2005 530i. The car is stock bluetooth and such, but with no GPS. The current battery is a lead acid battery which was installed by the dealer a little over 3.5 years ago. I had my brakes changed at an Indy shop and they ran auto logic as a courtesy. They got a battery fault which indicated that it's on the way out.

I began to look into purchasing an AGM battery because I heard they last a lot longer. The question is; is it worth it? I found 2 AGMs that I am considering, the first is an Interstate MT5- 49 H8. The retail on this is $293. The other is a Diehard Gold group 49 from Sears. The diehard cost $160. I have also heard that I can buy a Duralast H8 AGM from Autozone for $170. Do I go the AGM route or just replace with a good lead-acid?


Do I need to have the battery registered and reprogrammed regardless if it is an AGM or Lead Acid?


Which would you buy? Also, if any of you are in the Brooklyn or Queens area is there an Indy shop you recommend for reprogramming?

[GeorgeT]

I would get the AGM and definitely have it registered to the car.

[nyjam530i]

I would get the AGM and definitely have it registered to the car.

I understand that AGM is supposedly better than the lead acid. I want to know what is the real benefit? A guy at my dealership said his AGM lasted just over 1 year. The dealer installed a lead acid battery that has last for almost 4 years with zero issues.

Does the lead acid need to be registered to the car as well? There is an indy shop close to me which will charge $40 to register the battery. That sounds reasonable to me.

[meangreen94z]

AGM battery's are one of those ideas that sound great on paper, but don't seem to work out in the real world. The main benefit was supposed to be reduced sulfation during deep cycles. My real world experience is they handle a deep cycle worse than a lead acid battery. Some times one heavy discharge and they won't maintain a full charge after that.

[Booyaazaa]

Either battery will work good with the car. If you do switch to a agm you will need to actually reprogram the car for a agm battery which has a lower max charging voltage then a fla battery. The biggest thing that kills batteries is your driving habits. If you drive short trips all the time then you will kill any battery since the battery is not given time to finish a complete charging cycle. To fix that just hook up a battery tender every few weeks to top off the charge. Anyways most batteries come with a 5 yr warranty, you plan to have it more then 5 years then get a agm. If not a fla from autozone, dlg 95r, will work just fine.