AGM=Absorbed Glass Matt. Instead of plates immersed in liquid sulfuric acid, AGM plates are separated by fiberglass mats that are saturated (like a sponge) with a thickened electrolyte that stays in place (doesn't run off). These batteries can usually be mounted in any orientation. They are semi-sealed so they don't leak acid and they are valve regulated to limit internal pressure. They try to contain most of generated H2 and O2 and recombine back into water inside the battery. Optima gel batteries are similar but are spiral wound which limits battery dimensions (must be six cylinders).
Functionally, AGM batteries can deliver higher current, charge faster, tolerate deep discharge better, and self-discharge slower (compared to comparable flooded batteries). The Car Quest AGM battery in my tractor survived 13-14 years after it went dead several times. The problem is that new batteries can be very different from batteries made 5-15 years. Most "brands" periodically contract out to one of about five companies that actually make batteries, and even then they build to several specification levels. Flooded batteries can gave good service if properly maintained, which is rare, so they usually have shorter life. So AGM is should be superior in actual use but it is possible to make poor AGM batteries just like poor regular batteries. Scott -----Original Message----- From: Mercedes On Behalf Of Floyd Thursby via Mercedes Sent: Sunday, September 20, 2020 12:34 PM To: mercedes@okiebenz.com Cc: Floyd Thursby <buggeredbenzm...@gmail.com> Subject: Re: [MBZ] Batteries, was: Daimler cheated too? AGM is a type of battery Advanced? Gel Mat I think it means. Not your standard water/lead/acid type --FT On 9/20/20 12:17 PM, Andrew Strasfogel via Mercedes wrote: > Thanks, Ned. Is the Mercedes branded replacement battery for a Bluetec > car made by AGM or do you have to request it? > > On Sun, Sep 20, 2020, 10:13 AM ned kleinhenz via Mercedes < > mercedes@okiebenz.com> wrote: > >> I found AGM batteries are a really good thing. In the winter of 2019 >> my >> 2006 Mercedes E320CDI needed a new battery. When they checked the >> serial number of the old battery, it was found to be the original battery >> sold in >> that car when new. That was 13 years and 200,000 miles ago. I had >> the Mercedes dealer replace it with a new $300 AGM battery. >> >> >> >> In 2015, I had to replace the original AGM battery in my 2000 BMW Z3. >> All I could get quickly was a standard wet cell battery at Sears. >> That battery never performed well in the infrequent use this car >> gets. This summer that battery would no longer take a charge so I >> replaced it with a new AGM battery. A standard battery at O’Reilly’s would >> have cost $150. The AGM >> battery cost $200. The difference in life expectancy is ~5 years vs ~10 >> to 15 years. I believe the cost of an AGM battery is well worth it >> if you keep cars as long as I do. >> >> Ned Kleinhenz >> _______________________________________ >> http://www.okiebenz.com >> >> To search list archives http://www.okiebenz.com/archive/ >> >> To Unsubscribe or change delivery options go to: >> http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com >> >> > _______________________________________ > http://www.okiebenz.com > > To search list archives http://www.okiebenz.com/archive/ > > To Unsubscribe or change delivery options go to: > http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com > -- --FT _______________________________________ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com _______________________________________ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
