Strange battery issue

[80stech]

The starter takes more current as it gets older and a poor battery is also hard on the starter so it can become a downward spiral. Not to mention connections and alternator!

[getty150]

Yeah i'm going to take both starter and battery to Auto Zone they'll do a test for me .

Starter is done for!
Battery is good! So says AZ

[X5chemist]

Mine has an AGM Duracell. It's been working great for two years. Held up while chasing a parasitic drain. With only 11 mA while sleeping, it can start up even after almost two months of nonuse.

[X5only]

Installed BMW AGM battery. Got a good deal from my local dealer. My issue was clearly a worn battery: the car now starts up strong. The old battery lost charge pretty quickly even when I removed it from the car and tested it out before handing it to the dealer as a core. I'd installed an amp and subwoofer late last year and those obviously stressed the old standard battery accelerating its demise.

[80stech]

If you have a big cap on the sub amp they are a constant draw on the battery, just something to keep in mind.

[X5only]

Originally Posted by 80stech

If you have a big cap on the sub amp they are a constant draw on the battery, just something to keep in mind.

Thanks for the heads up. I don't have one.

[getty150]

Originally Posted by X5chemist

Mine has an AGM Duracell. It's been working great for two years. Held up while chasing a parasitic drain. With only 11 mA while sleeping, it can start up even after almost two months of nonuse.

Yeah, I use the Sam's Club (standard) Duracell...they can afford to swap it out when I have problems (as long as I'm under 3 year warranty)

Sent from my TMAF035G using Tapatalk

[Clockwork]

Originally Posted by X5only

Installed BMW AGM battery. Got a good deal from my local dealer. My issue was clearly a worn battery: the car now starts up strong. The old battery lost charge pretty quickly even when I removed it from the car and tested it out before handing it to the dealer as a core. I'd installed an amp and subwoofer late last year and those obviously stressed the old standard battery accelerating its demise.

I am noticing, after not driving my 4.4i after 30 days (travelling Europe) yet still on a C-Tek battert tender (storage mode) that my batt was BARELY starting my X5 and voltage, using multi-meter, shows just 10.6V. My batt is a BMW OE batt that was installed maybe 4 years ago.
SO does the BMW AGM battery promise anything better than the lead acid variety?

[80stech]

AGM is a big step up.

If your charger/maintainer isn't able to keep up though you might want to look into what the car is drawing in sleep mode or if it's getting to sleep mode.

[Effduration]

Originally Posted by 80stech

AGM is a big step up.

I am not sure this is the case for an 15-20 yr old BMW that did not come from the factory with an AGM.

I would be eager to hear your reasoning with an open mind.

I live in a place with freezing temps in winter..though not as cold as the Province of Saskatchewan...And in my experience they do not last longer, or crank harder in cold weather, than wet- cell batteries. This seems to be the consensus across the many E39, E46, E83, E53 BMW forums I participate in.

BTW, I have also read that hotter temp environments are tougher on car batteries than cold climates...

My wife's 2014 Mercedes came with an AGM from the factory and has charging systems suited to it. Our BMW's do not....AND as noted, if you charge or tend an AGM battery with the wrong charger, that will also shorten the AGM's life.

AGM's are likely no worse than wet-cell batteries, but AGM's are not worth the price premium in my opinion.