2007 Z-4 Dead Battery after replacement

Hi -

As if the snow in the Northeast wasn't enough, my battery was dead yesterday when I went to move my Z4 3.0i. I replaced the battery proactively in November of 2012, and drive the car regularly - it's not a summer only car.

I have had the car since it was new, and had a 2003 Z4 before it, and never had any problems with either not starting before. I have noticed that over the last few years, when the car has sat over night or longer, when I turn the key, the starter kicks in, and growls once, slows down, then gets it second wind and starts right up. This takes longer to read than it actually happens - all in about a second - never have to release the key. This seems to be the only noticeable "issue", but it was doing this before the battery was replaced, and it continued after it was replaced. After the car has been started, for the rest of the day this is not a problem, even though it might have set outside somewhere for hours.

I have seen some comments about locking the car when it sits in the garage overnight having some effect on the battery. Also the key battery might have something to do it. Anyone know about these?

Also, what is a reasonable amount if miles to drive a week to keep a good charge?

FWIW - overnight temperatures here in CT last couple of days were in the single digits, but when I tried to start the car, it was about 30. The car is stored in an unheated, detached garage.

Thanks in advance for any suggestions or thoughts.

Either you got a faulty battery when it was replaced or the charging system is not replenishing the battery while you are driving it.

If you have a volt meter, jump start the car, disconnect the jump start battery & check for the voltage on your battery. If it's not 13.5 - 14 volts, your charging system isn't working.

Good luck.
Fred

It's been an interesting couple of days.... I dropped the car off with the independent garage that did the battery replacement - they specialize in MB and BMW, so thought they would be a good start. They called back in a few hours and said that the charging systems were good, and that they wanted to keep the car overnight, to check for any problems in the morning, and to also charge the battery completely.

The next day, I went to pick up the car, and was surprised to find that this had all been done for free. Made me wonder; I would have expected some diagnostic charge, plus something to charge the battery. But never look a gift horse in the mouth.

I can't tell if the battery was replaced under warranty, as the battery was only a coupe of months old. The clock in the car had to be reset, so there was some sort of loss of power. I have been told that there is a manufacture date on the battery, but cannot locate. My info was that it was stamped on the negative terminal, but I can see nothing on the top of the post. (It is a Bosch battery). Is my info correct, or should I look somewhere else? I do not want to remove the cable from the battery.

The next two mornings, the car has started right up, as if it were the middle of summer.

Thanks in advance for your help.

Good to hear about a shop that stands behind their work.

What is the name and location of the shop? Shops that do the right thing deserve a little free publicity.

Do you keep the car on a 'battery tender'? If not, there is some of your issues. The car does go into 'sleep mode' after a predetermined period of time but some of the modules are still drawing power.

I have found that after about one month, without the battery tender, the battery is almost dead.
Both of my Z4's have to be on battery tender if they are not going to be driven for two weeks or more. My wife's 03 sits on a tender every winter (Nov to March) and all I do for the first start is pull the car cover off, remove the battery tender then place the key into position 1 (fully on) for 10 seconds. It then fires right up. If I am going to be traveling for more than two weeks, the same for the ///M.

In fact, the 03 has the original battery it was built with.... cold weather will KILL a not fully charged battery.


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Answers to a couple of posts...

1. The garage was Glastonbury Foreign Auto Repair in Glastonbury, CT. Have been very pleased.

2. I understand the need for a battery tender, but the car is driven all winter. It had been driven last 2 days before.

I have wondered about the use of heated seats, etc and how much they impact the battery on shorter trips. The longest I make is about 20 minutes or so this time of year.

Thanks to all who have replied. So far the battery is holding up.