Dead battery on the e46 m3
 

The weeks of snow/ice/salt enforced parking took its toll on the m3. Car didn't start on Thursday evening. I jumped it, drove it for 45 minutes.

It started on Friday evening, but this morning I took it Advanced Auto Parts. They measured 12.2V, 600CCA@26F. So that's 45 minutes of town but a bit revvy driving a day before and 8-10 minutes just before the measurement.

Battery is a Bosch 48-690B, rated 850CCA@32F, 690@0F. Interpolation gives me 820CCA@26F, so it was slightly below 75%. Since there is no plug/outlet that I can use in my condo garage, I pulled it from my car, brought it home and plugged it to my delran motorcycle tender/trickle charger. It might take a whole night or even longer for it to properly charge.

1. Will this battery fully recover?

2. If not, any recommendations on what to put in? This was about a $145 battery that the previous owner installed in 5/2012, so it has not even been 3 years. Since then, car has done about 8-9k miles (almost all with me). The bosch weighed in at 38lbs, I wouldn't want to go heavier, though I have no use for a light/racey battery.

I've always had hit, or (mostly) miss luck recovering dead batteries.

I picked up a battery from Walmart for mine earlier this winter after the original battery finally succumbed to age and the cold.

I think three years for a battery in a modern BMW is a clear win. Cut the loss and buy a new one. (Sorry, no knowledgable recommendation from me)

Eh. The E46 should do better than 3 years.

I'd be concerned about whether the alternator is starting to go.

My 00 528 had only one battery replacement, at 7 years and at 14 years the second battery was going strong. So I do think 3 is a bit short, though the year before I bought it the car only did 1k miles, so that may have done some damage. I probably should have someone check the alternator before I put in a new one... Thanks, Nick!

My M3 ended up with a dead battery due to a parasitic drain from the clutch, as I recall.

Ah, well some kind of parasitic drain is another possibility. I do have a clutch stop but more importantly the rather wonky Dice mediabridge Ipod player is wired in. That would be my prime suspect.

In my experience, this is likely to be the culprit.

I replaced my original battery last May in my 06 ZHP. I sprang for the OEM BMW setup - I thought 8 years was pretty good.

Back in the day, the theory being advanced on the old forum was that US BMW batteries aren't as good as the ones installed by the factory in Germany. The German ones were [then?] made by Varta, and the Interstate replacement I've posted about here some years back was also Varta. I think Interstate switched to their in-house MegaWhatever now, though.