[pobrienny]

Originally Posted by chollz

Here is the video of me starting my car after the charge... Still dropping under 10V during ignition. https://youtu.be/1g9XUTtYarU

Good troubleshooting! Battery voltage should never drop below ~10V under the starting load. If it does, that indicates excessive internal resistance which would show it needs to be replaced.

[mrpingu]

I am getting
8011F9 Electric auxiliary heater: Reduced heater output due to power
management

is this early sign of battery starting to show it's age?
I drive everyday 25 minutes to work, no other signs of weakness. Voltage when switched off is 12.6V, didn't test cranking yet but I don't notice any problems.

Winter is coming so low temperatures (-5C till -20C) and I don't have a garage to park the car overnight so tricklecharging / maintaining is not really option.

Battery is 5.5 years old but harsh winters here, but would expect since it's AGM that it still should be OK.

[Billfitz]

Are you using it to pre-heat the car? If so the car will reduce the current before it might impact the ability to start the car. That might not take long, electrical resistance heating elements use a lot of power.

[mrpingu]

Originally Posted by Billfitz

Are you using it to pre-heat the car? If so the car will reduce the current before it might impact the ability to start the car. That might not take long, electrical resistance heating elements use a lot of power.

No it’s not the pre-heater but the heater that is used when starting the car to have quicker warm up. I have Diesel, also called the PTC heater:

Since diesel engines are more thermally efficient than gasoline
engines, the warmup time is increased. This can potentially cause
a "comfort" related issue for the customer. So, this heater is needed
to "boost" the output of the heater core until the coolant
temperature is sufficient to provide the necessary heating.

Attached picture of battery before start/crank with ignition on.

[Billfitz]

That's lower than you want to see. If you were able to use a maintainer you could probably get through the winter, but since you can't you should consider getting a new battery. My battery is almost 9 years old, it still shows 12.4v or so before starting the engine.

[mrpingu]

Originally Posted by Billfitz

That's lower than you want to see. If you were able to use a maintainer you could probably get through the winter, but since you can't you should consider getting a new battery. My battery is almost 9 years old, it still shows 12.4v or so before starting the engine.

Hmm mine is staying stable at 12.2V at, no significant drop of voltage over 48 hours. So it fortunately it is not a parasitic drain but this battery is due for replacement. 12.2V is on the low side.

[erickonphoenix]

I got 10 years out of mine but I did let it chug for a while. Probably needed to go at 9 years.

[wendellthecat]

Mine lasted ~9.75 yrs. For very cold starts, the fuel gauge and tach would drop back down to zero, the cluster made clicking noises for 5-10 seconds before they came back to normal. Replaced it with a Walmart 92Ah AGM battery.

[Neue_Klasse]

In my F33 the battery lasted 8.5 years and approximately 110K miles. It is rather impressive that this battery lasted that long in a convertible that was daily driven with top closed/open nearly daily.

One more thing: I did get some transmission error codes when the battery was dying while I was driving, at some point car just stopped and I barely started it.
Another sign of a worn out battery is that you engine start/stop functionality will likely be disabled due to battery condition.

I was thinking to get a CTEK and recondition it, but didn’t have time and also didn’t have confidence that it will result in success. In the end, I just replaced it with a brand new Interstate battery from Costco.

[Neue_Klasse]

One more thing: battery I got was rated 95Ah, group size H8 (49).

[Billfitz]

Reconditioning isn't recommended with AGM batteries other than as a last resort.

[halcyon_waves]

2013 335i here (prod 09/2012 I believe) and still on the original battery. SoCal climate, 101k miles, never use auto start/stop.

Wondering if I should keep it going or change it as preventative. Seems like I still have a ways to go, but at the same time it's going on 11+ years - it's the longest I've gone without changing the battery in a car I've owned. Is there a difference between these batteries vs other cars that makes them last so much longer?

[Billfitz]

They're AGM, which last longer, and they're oversized, for the auto start/stop. They also last longer in warm weather, in part because the engine takes less effort to start in warm weather.

[lidation]

my '13 F25 X3's battery has the original battery and no issues. I recently replaced it with an Everlast AGM battery, only because I think 11 years is a very long time for a battery. But I live SF Bay Area where we rarely sees anything more than 90F.

[bluesport]

2016 330e, 200k km, both start battery and the main battery in trunk I assume to be original and they are going strong.

During my few years with the car I have once unplugged each and kept in workshop charger in "de-sulf" mode for 24h.

There is diagnostic info code for main battery "battery is aged".