Battery Registration And Bad Battery

[slattrick]

A month or two ago I replaced my 2008 328i starter and battery, the battery did not need to be replaced but I was wishing it was the easy way out if my car didn't need a new starter (which it did). I did not register the battery and now my car won't cold start unless I get it jumped. This has been happening for about 2 days now. I don't know what to do, do yall think I could just register the battery now and if so, how do I do that without bringing it to a bmw mechanic to charge me 150$.

[MarcoZandrini]

How long ago did you install the new battery? Did you have any indications that the battery wasn’t being properly charged? Registering the battery changes the charging protocol. That is, the process of keeping a new battery properly charged is different than that for an older battery. I think the process for keeping an older battery charged can over charge a new battery. Also, I’m wondering if the new battery is defective.
Software to register the battery: check the diagnostic software sub forum.

[slattrick]

i installed the new battery about a month and a half ago, and no, i did not get any indication the battery was not getting charged. the car worked just normal until a few days ago.

[MarcoZandrini]

My recommendation is to take the battery back to the seller and have the battery tested. A cell could be bad. If it’s ok I’d start checking the alternator. But, you’ve written that you had no indication of a charging problem. So I think that rules out the alternator.

I think the different charging protocols are a way for BMW to squeeze an extra 0.05mpg out if a car.

[slattrick]

I got a multimeter and tested to see how many volts my battery had after sitting over night and it was at only 6-7 volts then jumped my car to check if it was getting charged and it was, my guess is that since I did not re code the new battery, the alternator over charged it.

[MarcoZandrini]

Whet was the voltage at the battery when the engine was running? 6-7VDC means the battery likely has a bad cell or was almost completely discharged. Take the battery out and get it fully charged. See if it holds that charge. The charging protocols for a new battery vs an older battery aren’t that different. Basically it tried to not charge an older battery too quickly, but it still charges the battery!

[slattrick]

the voltage when the car was running was above 14. and I agree, I did not re code the car for the new battery and it probably overcharged it

[MarcoZandrini]

I’m not up on the specifics of the battery charging protocols but I don’t think the alternator over-charged the battery to the point it fried a cell or 3. Take the battery back to the seller and have it tested. Second thought: how accurate is your meter? Can you try measuring another car’s battery? Just trying to rule stuff out.