How old is your battery?

[repenttokyo]

You are correct. Heat kills batteries. Cold climates cause the cells to lose power, but it comes back as temps warm up. Heat actually cause the plates to be destroyed.

not all batteries come back in the cold, not even when the summer comes around again. Draining the charge completely from the battery in the cold will often kill it forever.

[gale]

My previous Autozone Duralast group 49-D, 7 year battery lasted almost 6 years to the day from the date I bought it. It died completely over a period of about 3 days, prolly a dead cell. For $59, that's not a bad deal, they even come with the vent tube business for under the seat. They also gave me 1 year prorated credit for the 7th year. I replaced it with the same one.

Here's Bill Darden's link (Denmark?) with lots of good lead-acid battery info:

http://www.batteryfaq.org/

[cary]

My previous Autozone Duralast group 49-D, 7 year battery lasted almost 6 years to the day from the date I bought it. It died completely over a period of about 3 days, prolly a dead cell. For $59, that's not a bad deal, they even come with the vent tube business for under the seat. They also gave me 1 year prorated credit for the 7th year. I replaced it with the same one.

The price has gone up on these to $84.99. Personally, I don't like Autozone and went to Pep Boys where they sell the same battery with a slightly better warranty for $94.99, and they matched the price when I asked.

[Ross]

Lots of lead in those BM batteries, that's why they last.

[KenB]

My original BMW battery was 14 years old when I replaced it last fall. Got the Duralast.

I had a starter that was going and probably contributed to the battery's demise. Although at 14 years I replaced it at the first sign of weakness before last winter. (Threw a couple of fault codes for weird stuff related to insufficient voltage) Other than that I had never seen a CEL

[ryan roopnarine]

in flor-ada, it seems that everyone, regardless of make/model, has to replace their battery every 2-4 years. our 99 taurus ate the original battery in 2002 (4 years) in 2005 (i think this was a sulfate from not being driven though). my e34 had one put in by the PO in 2001, which i had to replace in 2003 (from not being driven, most likely). the 49d appeared to die this summer, but a few cycles on deep cycle seemed to bring it back to life (not being driven often).

[artguy]

I went out yesterday afternoon and did the #9 test (Battery Voltage) on the OBC and mine read 12.09. Zero charge is 11.89 and a good battery is supposed to be at 12.65+. So I'm going to start looking to get a new battery.

[Macv]

haha, mine is below 12. Life is good.

[Jehu]

Alot has to do with the health of your starter... Old starter will strain and kill your battery faster... I just came to this conclusion this weekend... wondering why this E34 battery doesn't last long regardless of brand.

When you crank, it should be instant and fast cranking... If your BMW feels like no power when you first try and second time it cranks over just okay, then it is most likely your starter is on the way out... like mine. After this first crank on hot engine, starter kicks over like a champ. I am probably gonna wait for a sale before I pick one up.

Good starter use less amperage to turn over engine and bad one suck em all.

What is going on if your lights dim slightly when idling then brighten when you accelerate?

[RallyD]

What is going on if your lights dim slightly when idling then brighten when you accelerate?

clean the contacts on the alternator cable and the major grounds.