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 BatteryPlus. 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.

[andrewwynn]

Somebody on xoutpost did similar but magnetic connector inside front left wheel well. (auto disconnect if forget when backing out)


Sent from my iPhone using Tapatalk

[80stech]

@OP The AGM batteries are way better at "hanging on" (and seem to not self-discharge at all) if there is a parasitic draw so it would be best to measure the draw to make sure and not assume there isn't one especially if you suspect something is wrong.

If you don't already know, if letting the car sit for any length of time then maybe give the keyfob an extra push on the lock button immediately after the first push, the clown nose should give a long flash indicating the interior sonic sensor is disabled so less drain on the battery if it gets triggered (which you probably wouldn't even know because the alarm horn probably doesn't work! ) and what ever drain from the sensor it self.

[swissrock]

My real life experience on this topic, daily all year driver in swiss climate (cold winters/hot summers) :


An AGM battery (Bosch) had already been installed by the previous owner: I haven’t had any problems at all in the 1.5 years I’ve owned it, even though the car has a lot of electrical components and even an auxiliary heater that’s used frequently in the winter. The M57 diesel engine is also a bit more demanding when starting up.

So I’d say, yes, an AGM battery is compatible with our E53.

[Blowout]

Originally Posted by 80stech

@OP The AGM batteries are way better at "hanging on" (and seem to not self-discharge at all) if there is a parasitic draw so it would be best to measure the draw to make sure and not assume there isn't one especially if you suspect something is wrong.

If you don't already know, if letting the car sit for any length of time then maybe give the keyfob an extra push on the lock button immediately after the first push, the clown nose should give a long flash indicating the interior sonic sensor is disabled so less drain on the battery if it gets triggered (which you probably wouldn't even know because the alarm horn probably doesn't work! ) and what ever drain from the sensor it self.

Just checked the AGM battery again and it's 12.81V. No charge applied since 7/1 (12.75V), so 5 days and the voltage even went up slightly.
I've thought over the years there was a parasitic drain with this car but never tested for it.

Only things I can think of is the alternator isn't consistently charging the battery or maybe a ground strap isn't secure and the battery isn't getting charged properly. Probably 12 or so years ago a tech forgot to reattach the engine to body grounding strap after doing some work and the battery died because it wasn't getting charged. Took it back and they reattached the strap and all was good... or so I thought.

I'll likely change out the alternator next. Any suggestions on what to get?

[80stech]

Check the charging voltage at the battery and alternator amperage output first, unless it's about time to change out the alternator anyway, but even then it's nice to know exactly what's going on. I think the rebuilt alternators are a bit of a crap shoot for quality. Taking a real life load out of the battery or alternator is the best way to test, there are some good threads on that and one of or members did a good summary. Also some good threads on checking for parasitic draw.
Checking all the grounds, the underhood battery terminal, alternator and starter connections always good idea and often missed. BST connection can be a problem but not so common.

[andrewwynn]

I only used AGM with my e53. I never charged other than driving.

When the battery i bought with the car failed, the failure mode was that it had plenty of current to crank but no reserve: 8 minutes of hazards meant i needed a jump start.

You kept saying battery died battery died. You just mean it was drained flat? If the car off drain is excessive def track that down. It should handle 2–3 weeks standby.


Sent from my iPhone using Tapatalk