AGM battery compatibility with e53 alternator

[motordavid]

Originally Posted by sroth004

Old school 1.25 amp Battery Tender brand on all the cars when they sit for more than a couple of weeks. Works fine through the under hood charge/jump lugs on the e53, e46, e39 and e90; all are AGM and 6-8 years on a battery ...

Same here: on the 5th? or so replacement batt on our 2001 E53, (current batt is probably 5 or 6 yrs old and maybe ready for R&R?), and have been using an AGM batt, (various brands) since the OE batt died couple decades ago.

Same for our 2002 Vette Vert, since the OE batt died in ~ 2005...

Same old Batt tenders, decades old, for charging.

One or both of those cars gets a long rest 'sleep' also for winter season in garage, and I usually attach Batt Tender, very well electrical taped tight on the under hood lugs, and the tender plug wire attached to an old fashioned mechanical appliance timer: set to come on/charge a couple days a 'week' for 12 ish hours.

Knock on fookin wood, not prob with that rig job, but it has worked flawlessly for me, for a couple of decades.

Edit, Add On: thinking about 'my batt situ', up until a couple years ago I had 4 motorcycles in the stable, ranging from a pristine 1987 Hurricane 1000, a '94 Goldwing, a 2002 HD Soft Tail and my 1st 'new' m'cycle, a 1975 HD Superglide. I went to AGM batts for my Scoots as soon as a specific AGM batt model was available for each, way back when.

All the batts worked well, none were affected by what ever alt/charging system, etc. And, I 'know' v little about vehicle alternators, etc, but AGM batts have worked nearly flawlessy for me over the decades.
GL, mD

[X5chemist]

Mine has run a Duracell AGM 720 CC amps battery SLI49AGM since 2/6/21. It was recommended by BatterPlus. No issues on running it. I do connect a 4amp battery tender if it has extended time down time before starting it up.

[Blowout]

I added charging terminals accessible by removing the cover on the bumper where a tow hitch mounts. These connect directly to the battery terminals with heavy gauge cables. I attach the battery tender to these and put a piece of tape on the steering wheel that says " disconnect the charger" so the wife doesn't back out of the garage with the charger attached.

Battery still shows 12.8V after sitting 4 days without the battery tender attached. The alternator might not put out enough voltage/amperage to charge the AGM battery up all the way.