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Discussion Starter #1
This one has me stumped. I've looked everywhere but can't seem to figure it out. Here's the problem.

Last Sunday I drove home from Church and stopped at my house for about 10 minutes before heading home to work. When I got back in the car, it would not start. It would not even attempt to turn over. Although it seemed like a dead battery, all of my electronics (including my headlights) worked. I took another car to work, and when I got back I tried it again and it started fine. hmm? About 5 mins later I ran a battery test on it (by holding the trip reset and putting the key in the start position, clicking the reset button until test 9 shows up, then select 9, etc) The reading was about 120. I'm assuming this is 12.0 Volts? When I tried to start it immediately after that, it did the same thing as before work, unresponsive.
I jumped it from my dad's Ford Expedition and let it charge for about a minute, ran a battery test (with a reading of about 124), and it started fine. It continued to start fine for the rest of that day and the following day. It has been running fine for about a week since then. Today, I drove it to work, but after work it started being stubborn again. It acted like it was a completely drain battery although all the electronics worked fine. This time, jumping it was unsuccessful. We took it to Wal-Mart to get a battery test and they said the battery was fine.

Addition details- I have had some work done the last couple of months including-
New water pump​
new belt tensioner and belt tensioner pulley​
new idler pulley

The battery is about a year old and has not been drained in its lifespan.
The car is 2004 325i with 78xxx miles.
No "check engine" lights have popped up..


Help please.
 

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Battery should read 12.5 volts after one hour of no load. Less than that indictes a weak battery and e46 has very finicky electronics.

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Discussion Starter #4
Thanks for the help. I just got it started by just taking the connections off and back on the battery. It seems to me like it is completely random.
 
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