So I have an 07 530i and have owned it now for 3.5 years or so. I am going in for an oil change and have 54k on the clock-I am wondering if I should go ahead and change the battery. I figure its getting close to being bad and I hate getting stuck--is there a way to check how much life is left in a battery? do they do that at the dealer?

 

I'm pretty sure there's a way to check. I've had mine replaced at about 64k miles. Make sure you use an OEM one - do some research on this forum, there're lots of threads that go over this

 

I know but could not find any on how you actually check battery life-I know you can check if its holding a full charge but does that have anythin to do with life?

 

Sure...but you might want to check with your 3 series forum buddies.
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cant help but read any post I make huh-who owns you now-get a life

 

Put a voltage meter on it while off and on. Check to see how severe the voltage fluctuations are when running your accessories : AC, on/lights etc..


If its still putting up steady voltage it could be fine. Battery life could be described similar to that of a light bulb, their life expectancy follows more like a bell curve. I've had oem batteries in the past last 15k miles and others 75k+.

If you have long time installed aftermarket accessories(i.e. amplifiers) pulling current and fluctuating the voltage close to 12v while car is running, you likely want to start looking to replace it soon enough before it starts to affect the alternator.

 

the factory battery has a "eye" on top of the battery where you look in to see if it is good. it should be green.

my general rule is to not keep a battery for more than 5 years. the manufacture date is stamped on top of the negative post.

 

I am pretty sure that the indie shop that got me the battery had my car for a few days, all the while they were checking the output each morning and came to a conclusion that the old one was no good - even though I had no issues at all. I got it anyway, because I figured it was good as a preventative measure anyway.