battery died in Z4, replaced it, now won't start. EDIT: BAD STARTER KILLED BATTERY

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TechBoyJK

Lifer
Oct 17, 2002
16,699
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I have a 2004 bmw z4 3.0 with 72k miles. it had the original battery in it.

over the past week I started noticing that my electrical system seemed weak. it was getting harder and harder to start my car, the top was struggling to go up and down, etc.

Yesterday, I went to start it after work, and it really struggled. I thought it might be my starter, but on my way home I cranked the stereo, AC, car seat heaters, etc. so I could try and put as much drain on the battery as possible. When I got home and parked it in my garage, I shut it down, and tried to restart it. It struggled to start (as if the battery were dead) and never turned over. Stereo struggled, etc. Battery was dead. I jumped it and it worked fine.

I had the battery tested and it tested bad.

So I bought a new one, and it fits perfectly. Has the vent and all. Got it hooked up, and all the electronics work fine. Everything seems ok.

however, now it just won't start. I go to turn it over and it just clicks. Nothing.

I read online where someone had a similar problem, and it had to do with security codes (anti theft) being reset. They had to go have their keyfob reconfigured to the car.

I'm going to talk to the dealer tomorrow but I'm just curious if anybody has any experience with changing batteries on a bmw and if they think it could be anything else.

Thanks!

EDIT: Ended up having it towed to the dealer (bmw paid for the towing) since it was under warranty and diagnosing the problem was outside the scope of my small garage's capabilities.

They called this morning and said the starter was dead. They think the life cycle of the battery (near end of term) helped the dying start go quicker.

The battery was near end of life anyway.

Since the battery was on the weak side, the failing starter really took it to the battery because it had to crank harder and longer, putting extra work on the battery when it was it's weakest. As the battery got weaker, the starter, which was already failing, had to work even harder and harder because it wasn't getting enough juice, creating a "house of cards" situation where they killed each other.

Under warranty. Free fix, get new starter and full audit of the car (since they need to figure out if something caused the starter to fail). Good thing since my warranty expires in a few weeks and this gives them a reason to find stuff that could go wrong. (they want to find things, since they charge BMW NA for the work).
 
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SpatiallyAware

SpatiallyAware

Lifer
Sep 7, 2009
12,960
3
0
The chipped part is probably a separate system.. On motorcycles you turn the key to on/off/acc a certain number of times etc to reprogram the keys
 
Zenmervolt

Zenmervolt

Elite member
Oct 22, 2000
24,514
34
91
The click you're hearing is the starter solenoid. The starter draws far more amperage (up to 200 amps while cranking the engine) than anything else. It's no only possible, but common for the headlights, radio, etc to all work perfectly even when the battery is too low to start the engine.

Also, from your description, it sounds like there might be an issue with the charging system. Once the car is running, it should not be possible to drain the battery; all electronics should be able to be supplied by the alternator (assuming everything's stock) and there should still be enough residual capacity to top off the battery.

Double-check all the connections for the battery cables and the starter. Chances are that the fault is in those cables somewhere or in the charging system itself.

ZV
 
BoberFett

BoberFett

Lifer
Oct 9, 1999
37,562
9
81
Zenmervolt said:
The click you're hearing is the starter solenoid. The starter draws far more amperage (up to 200 amps while cranking the engine) than anything else. It's no only possible, but common for the headlights, radio, etc to all work perfectly even when the battery is too low to start the engine.

Also, from your description, it sounds like there might be an issue with the charging system. Once the car is running, it should not be possible to drain the battery; all electronics should be able to be supplied by the alternator (assuming everything's stock) and there should still be enough residual capacity to top off the battery.

Double-check all the connections for the battery cables and the starter. Chances are that the fault is in those cables somewhere or in the charging system itself.

ZV
Click to expand...

Sounds to me like the alternator is fine based on:

Yesterday, I went to start it after work, and it really struggled. I thought it might be my starter, but on my way home I cranked the stereo, AC, car seat heaters, etc. so I could try and put as much drain on the battery as possible. When I got home and parked it in my garage, I shut it down, and tried to restart it. It struggled to start (as if the battery were dead) and never turned over. Stereo struggled, etc. Battery was dead. I jumped it and it worked fine.
Click to expand...

I had the alternator go on a car, it was very obvious what was happening. When I pulled up to a stop the lights would dim, the radio would cut in and out, etc. If the car runs fine but has trouble starting it sounds more like a battery issue.

Based on the description in the OP, it does sound more like a computer problem. Everything works with the new battery except that the car doesn't start. Sounds like it may very well be a security system issue.
 
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Painman

Diamond Member
Feb 27, 2000
3,728
29
86
Start with the easy stuff. Test the new batt's voltage with a multimeter. Scrub the battery cable clamps' contact surfaces throroughly with a hard abrasive (wire brush, sandpaper, etc). They might not look terrible, but they can, and will, fail to make good contact with a new set of battery posts. It takes very little corrosion to hose a starter's current flow.
 
PlasmaBomb

PlasmaBomb

Lifer
Nov 19, 2004
11,636
2
81
Yup, check the battery voltage and giving the contacts a good clean is a good start and certainly cheaper than going to the dealer!
 
Colt45

Colt45

Lifer
Apr 18, 2001
19,720
1
0
Make sure you tightened the posts, a lose connection might pass enough for the radio and lights, but won't spin the starter.
 
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TechBoyJK

Lifer
Oct 17, 2002
16,699
60
91
Battery cables look fine. Nice and snug, no corrosion.

I do think it was a matter of the battery going dead. I was the original, and the car has 72,000 miles and is about 7 years old. I think it's expected.

It was my understanding that accessories typically use the battery and the engine things use the alternator.

In the days leading up to the battery dying, i noticed the electrical system getting weaker and weaker. My convertible top would struggle to open and close, car stereo sounded "weaker" than normal. After replacing the battery, these things are fine now. The top is acting normal. So the car acts like it's got full juice again.

Also, when it started to fail to turn over, I would click click click and start to turnover but wouldn't. After replacing the battery, it's just one click. The starter doesn't even sound like it's getting a signal. Makes me think the security system has the starter killed.
 
LTC8K6

LTC8K6

Lifer
Mar 10, 2004
28,520
1,575
126
It was my understanding that accessories typically use the battery and the engine things use the alternator.
Click to expand...

Engine running, alternator providing electrical power.
Engine off, battery providing electrical power.
Engine running and alternator inop, battery providing electrical power.

Also, when it started to fail to turn over, I would click click click and start to turnover but wouldn't. After replacing the battery, it's just one click. The starter doesn't even sound like it's getting a signal. Makes me think the security system has the starter killed.
Click to expand...

I'm thinking this is a battery problem. Next thought would be a starter or solenoid problem.
 
LTC8K6

LTC8K6

Lifer
Mar 10, 2004
28,520
1,575
126
In the days leading up to the battery dying, i noticed the electrical system getting weaker and weaker. My convertible top would struggle to open and close, car stereo sounded "weaker" than normal.
Click to expand...

If that "weakness" happened with the engine running, then your alternator could have been laying down on the job. That is, it could have been failing.
 
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TechBoyJK

Lifer
Oct 17, 2002
16,699
60
91
The only reason I don't think it's a starter problem is how it acted before and after replacing the battery.

Before, it would just struggle to start. After, it doesn't even try.
 
LTC8K6

LTC8K6

Lifer
Mar 10, 2004
28,520
1,575
126
9 times out of ten, a loud click when you turn the key indicates a dead battery.

The click is the solenoid, a big relay that turns on your starter motor. The battery is strond enough to activate the solenoid, but not to run the starter motor.

Accessories just don't require the power that the starter motor does. The fact that the accessories work is not an indication that the battery is okay.

I'd be looking at the battery and then the starter first.
 
amdhunter

amdhunter

Lifer
May 19, 2003
23,332
249
106
How many times did you try to start the car? We flooded a car once trying to start it over and over and over...and over.

If it's turning, it's not the anti-theft.

When my Galant died a few years back, it took a car + jump starter connected at once to turn it over. Maybe connect a jump starter on top of it?
 
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TechBoyJK

Lifer
Oct 17, 2002
16,699
60
91
I got the MM out. The car battery is DC right?

I probably tried starting it only 2-3 times after I noticed the battery was drained. Everytime after starting it with the new battery, it doesn't even attempt to turnover. Before changing the battery, it would attempt to turnover but struggle like the battery was dead/dying.
 
LTC8K6

LTC8K6

Lifer
Mar 10, 2004
28,520
1,575
126
Yes, 12V DC. Check the actual voltage with nothing turned on, then check it with the headlights turned on.
 
LTC8K6

LTC8K6

Lifer
Mar 10, 2004
28,520
1,575
126
I don't really hear a solenoid clicking in the vid, but it's hard to say.

See what the battery voltage is with and without a load, first.

It could be the anti-theft system.
 
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