[DeadPon1]

Hello everyone,

I purchased an 03 BMW 330i a few months ago as my first car and I absolutely love it. However, with it being my first car, I ran into a problem the other day that I don't know what it could be said from it being either the battery or alternator.

I was cleaning out my car and moved it towards the front of my house without any hitch. Then when I was finished, I went to start it up again and it gave me clicking noises with the dashboard pulsating. I've had this problem in the past which ended up being a dead battery - so I bought a pair of jumper cables. When trying to jump the car, it was still giving me the problem of a pulsating dash and clicking.

In testing the battery tonight (which I'll add its cold so I know the battery is cold) using the self test, it says it's at 7v and not 14.3 which I know is a fully charged battery.
Is it just a bad jump? Do I need a new alternator? Or is it the battery? Is there anything else I should check? If so, please let me know. This is my first car and I love her so much and I'm always willing to learn more about her so I can diagnose these problems myself in the future.

Thank you very much and I anticipate your guys' responses.

 

[tommy d]

Ok, here are a couple quick tests to determine what your issue is.
Probe the battery with car off, it should read above 12V, or 12.5V approx. If not, you need to replace the battery.
With the battery actually reading 7V, the battery is toast. You probably couldn't jump it, because at that low a voltage you need a lot of cranking power from the other vehicle to actually jump it.
If the battery is 12V, and you start the car, probe the battery again, and you should have 14V approx. That means the alternator is working correct.

I personally would replace your battery now and it seems this is the issue and you also don't know how old the current one is. This way you know your good for another 5 years.

 

[DeadPon1]

Ok, here are a couple quick tests to determine what your issue is.
Probe the battery with car off, it should read above 12V, or 12.5V approx. If not, you need to replace the battery.
With the battery actually reading 7V, the battery is toast. You probably couldn't jump it, because at that low a voltage you need a lot of cranking power from the other vehicle to actually jump it.
If the battery is 12V, and you start the car, probe the battery again, and you should have 14V approx. That means the alternator is working correct.

I personally would replace your battery now and it seems this is the issue and you also don't know how old the current one is. This way you know your good for another 5 years.

Thank you fir your response! By probing the battery,, you mean using a multimeter? I'm sorry. I'm so new to car things.
And if I need to change the battery, I know I need to get I programmed so the on-board computer knows its a new battery, can Walmart do that? Or can that be done by places like ORiellys?

 

[MrMCar]

I've jumped with cables cars with a completely flat battery, can be done but you need to follow a few caveats:

Donor car is running. Positive to positive under the hood of the dead car. Never on both batteries!
Negative first on the donor, then onto the ground post under the hood of the dead car. Once that connection is made and if it's good you will hear the alternator from the donor working hard.

Now wait 5 minutes, I know it's hard. Sometimes the donor car needs some 1,200 RPM just as you start the dead car. Start the dead car and let it stabilize about 30-60 seconds. Then just before you disconnect the negative cable, turn on the headlamps. This acts as a buffer when the two cars are separated. Then after a moment (let's say while checking voltage at the cluster 19/9) disconnect the cables and turn the lights off. Voltage half decent?

You need to check charge rate, the battery's health and ability to HOLD a charge, and eventually for parasitic draw.

But charge the battery for at least 6 hours, if not longer. Lower/slower charging rates over longer periods of time are better for the battery's health.

 

[RRRM8E]

Ok, here are a couple quick tests to determine what your issue is.
Probe the battery with car off, it should read above 12V, or 12.5V approx. If not, you need to replace the battery.
With the battery actually reading 7V, the battery is toast. You probably couldn't jump it, because at that low a voltage you need a lot of cranking power from the other vehicle to actually jump it.
If the battery is 12V, and you start the car, probe the battery again, and you should have 14V approx. That means the alternator is working correct.

I personally would replace your battery now and it seems this is the issue and you also don't know how old the current one is. This way you know your good for another 5 years.

7V may be toast; how old is the battery?
In general if a battery is less than five years, an attempt should be made to fully charge it and then see if it will hold a charge. It should get up to around 12.5, but maybe less is its really cold. If it doesnt hold charge its toast.
Also clean and tighten all battery cables including under the hood. Low batteries can be the result of several things, so dont rush off to buy a new one until you confirm its the culprit.
Now, did you get any service records? How old is the cooling system?

 

[Hani]

And if I need to change the battery, I know I need to get I programmed so the on-board computer knows its a new battery, can Walmart do that? Or can that be done by places like ORiellys?

That is incorrect information. There is no need for programming when you replace the battery on an e46.

 

[Open Highway Productions]

7v on an automotive battery is a death sentence, especially in cold weather. Batteries operating near 11v or less is very bad. 12.6v is normal with the charging system putting out 14v. I recently had a problem with a loose positive cable from the alternator to the starter cause intermittent start and charging issues. Loose nut on the starter caused it.

 

[MrMCar]

Thank you fir your response! By probing the battery,, you mean using a multimeter? I'm sorry. I'm so new to car things.
And if I need to change the battery, I know I need to get I programmed so the on-board computer knows its a new battery, can Walmart do that? Or can that be done by places like ORiellys?

First of all the E46 DOES NOT need "battery registration."
Second: Stay away from Walmart or ORiellys unless you know what you are doing and are shopping a quality part on price alone.

 

[77'911]

If you buy a new battery, I went with NAPA's AGM type and has been exceedingly reliable. The CCA is above BMW's factory battery.
regards

 

[kaboom28]

I've jumped with cables cars with a completely flat battery, can be done but you need to follow a few caveats:

Donor car is running. Positive to positive under the hood of the dead car. Never on both batteries!
Negative first on the donor, then onto the ground post under the hood of the dead car. Once that connection is made and if it's good you will hear the alternator from the donor working hard.

Now wait 5 minutes, I know it's hard. Sometimes the donor car needs some 1,200 RPM just as you start the dead car. Start the dead car and let it stabilize about 30-60 seconds. Then just before you disconnect the negative cable, turn on the headlamps. This acts as a buffer when the two cars are separated. Then after a moment (let's say while checking voltage at the cluster 19/9) disconnect the cables and turn the lights off. Voltage half decent?

You need to check charge rate, the battery's health and ability to HOLD a charge, and eventually for parasitic draw.

But charge the battery for at least 6 hours, if not longer. Lower/slower charging rates over longer periods of time are better for the battery's health.

OP, this from MrMCar is good advice. Since this is your first car and new to you, I want to remind you that BMW designed locations under the hood for you to jump start the car if needed. See this pic. Flip open the cover (POS) for a post to connect the positive end of your jumper cable. The negative (NEG) post is where you can connect the negative end of your jumper cable. Good luck.

 

[DeadPon1]

OP, this from MrMCar is good advice. Since this is your first car and new to you, I want to remind you that BMW designed locations under the hood for you to jump start the car if needed. See this pic. Flip open the cover (POS) for a post to connect the positive end of your jumper cable. The negative (NEG) post is where you can connect the negative end of your jumper cable. Good luck.

View attachment 941761

Thank you very much. I have had to jump start it before and was told to use the ones under the hood.
I'm waiting for a friend to let me hook the car to a jumper cable for a little while to see if that works. If not, I'm going to go to NAPA near me and get a new battery.
Thank you all very much and I will update the thread when I get a result.

 

[RRRM8E]

Again, how old is battery?

 

[RRRM8E]

There should be a date on top. My point is that it may well be the battery, but there are other things that can cause even a brand new battery to run down.

 

[Sapote]

............
Then just before you disconnect the negative cable, turn on the headlamps. This acts as a buffer when the two cars are separated. Then after a moment (let's say while checking voltage at the cluster 19/9) disconnect the cables and turn the lights off.

All are good but I don't understand the need of turning on the headlights before disconnecting the jumping cables. Turning on the headlights at this moment will cause more loading on the dead car's alternator which is charging the dead battery at very high current, so I would not add more load to the stressed alternator with the headlight turned on. What is the advantage of turning on headlights?

 

[MrMCar]

Well we're not sure if if/not a bad alternator.

Turning on the alternator on cars before DME controlled charging rates (<BST) is a VG idea.
Case in point: Battery completely flat. Jump start car and it runs, albeit off of the jumping car. You remove one of the jumper cables and now the alternator senses a high demand. Oh you need everything: Here you go, 140 amps right at you! The second you remove one of the cables.

This produces a huge spike. Could be damaging to some modules. The headlamps (a buffer) takes some of the load shedding.

 

[DeadPon1]

@ALL,
I got the battery tested at Oriellys and they said the battery was good - but on its last quarter of life. After I got home and put the battery back into the car, it's starting to turn, but not fully enough to turn over. These are the readings I'm getting with the self test. What do y'all think? She dead?

 

[Sapote]

Oh you need everything: Here you go, 140 amps right at you! The second you remove one of the cables.

This produces a huge spike. Could be damaging to some modules. The headlamps (a buffer) takes some of the load shedding.

I understand. This is the reason why the suggestion to keep the donor car running and connected for 5 minutes to help charge up the batt and less stress on the bad car alternator. After 5 minutes the flat battery should be high enough that the charging current should be less than 20A. The headlights are sourced the power near the battery connection, the same as all other elec modules, and so the spike voltage seeing at the alternator output is filtered out when reaching the battery which is also acts like an excellent big capacitor to filter the spike. I still don't think adding the headlights load to the current helps anything to the spike, but the opposite: because the headlight load robbed the charging current that instead should be charging the batt faster to its normal state (the headlight loading delay the process of battery recovery).

 

[MrMCar]

Unless it has a shorted cell.
I do everything I can to avoid buying control units.

 

[RRRM8E]

One last try. You need to get the battery fully charged. With a battery charger. And clean the cables to be sure.
If its more than 5 years old, I'd replace anyway. But you don't seem interested in determining age or following up on suggestions above.

 

[kaboom28]

@ALL,
I got the battery tested at Oriellys and they said the battery was good - but on its last quarter of life. After I got home and put the battery back into the car, it's starting to turn, but not fully enough to turn over. These are the readings I'm getting with the self test. What do y'all think? She dead?

I would get a replacement battery.

Edit: you need power to the starter, which is a combination of Voltage and Current. Your voltage is low and I suspect (can't prove without being at your battery) that your current is low based on your saying the engine is not turning over.