F30 340i won't start, even with perfect battery

[kgosi_f30_340i]

I have an issue that sort of started a few weeks ago. I would get a battery discharge every 3-4 days when I start up the car and won't get it for 2 days or so again. Then last week Tuesday I drove about 20km from my house, parked at a restaurant and when leaving the restaurant 2 hours later the car wouldn't start. I would hear the ignition go on after pressing the start button, but no start. I jump started the car assuming it has to be the battery and that worked.

After a few days I figured out that the boot latch had a fault which kept the boot light on when the boot is closed, which I assume may be draining the battery. That is now fixed. I also disconnected a faulty light on the passenger sun visor which I believe the switch on the open/close mechanism is broken. I then took in the battery to be tested and the battery is perfectly fine. 90% on condition and 85% on charge. I then tested voltage on the battery while connected to the terminals and all is perfectly fine. Reading a 12.6v while the car is off and a 13.7v while the car is on. But still not starting on its own, need to use the jumper pack in order to get a start.

Next was checking for parasitic draw so I did the whole process of testing every single fuse from all fuse boxes and nothing is drawing power while the car is off. Then I tried to see if I can see what the voltage drop on the battery is after attempting to start and it is huge. I charged the battery to 13.0v and attempted to start the car without the battery pack, didn't start. I then checked the battery again and now I was on 12.3v. This means (as far as I can tell) the starter is pulling more power from the battery and discharging the battery after attempting to start, dropping the battery voltage.

Is there a reason this could be happening? I would assume because the car starts with no issues when plugged to a jumper pack, the starter is actually fine. I have tried looking for where the starter relay is but I can't find it.

And also what would be my next step? I really don't want to have to take the car in if all I need is to change the relay but looking for advice on what else could be causing this and if its a common issue or not.

 

[Riaad]

And have you scanned for any codes ? might help narrow down the issue

 

[kgosi_f30_340i]

And have you scanned for any codes ? might help narrow down the issue

Yeah so because it's a "battery" issue according to the car. I get errors on modules that switch off when there is a fault

• Stabiliser error
• Brake error
• Tire pressure error
• Steering lock error

But soon as the car starts with the battery pack, the codes clear and all functions are back to working fine. Then I would scan and clear the codes so they are not stored which I assumed at some point was the issue. Still soon as I remove the battery pack, car won't start. And the errors only come after I try switching on the car the second time around.

 

[TurboLlew]

The 13.7 it is reading is the alternator output. The 12v battery can have a dead or dying cell that reports the correct voltage, but cannot supply sufficient cranking amps when called upon to do so. If you are not using a battery tester that tests load/CCAs it won't show this. However you have tested this for yourself in a sense by supplying and making up for the loss of capacity by using the booster.

If you are able to, I would test another battery in the car and confirm.

One other area to investigate is the IBS: There is an intelligent battery sensor that these cars have that can also be the source of various issues if the car was boosted. Your initial issue may have been caused by one of the other faults you mention causing the battery to be discharged, but the boost might have damaged this module causing the starting issue. Maybe google a bit about this and see if it might apply to you. There are ways of bypassing it to check as well.

 

[kgosi_f30_340i]

In an interesting turn of events, the car just starts fine this morning. No weird crank sounds or errors returned, nothing! It didn't start yesterday which is confusing. I did a battery check while the car was on and I am getting these readings:

I also did it with a multimeter and getting the exact same reading. Seems rather high.

 

[Schalk94]

I reckon you need to do a proper load test on the battery,as Volts only tell half of the story. If a battery loses volts so quickly when trying to start the car,the battery might be damaged already thus not holding a load the way it should

 

[kgosi_f30_340i]

I reckon you need to do a proper load test on the battery,as Volts only tell half of the story. If a battery loses volts so quickly when trying to start the car,the battery might be damaged already thus not holding a load the way it should

I did take the battery in to battery centre and they tested health, charge and did a load test and all looks good.

 

[Solo Man]

I suggest you check all earth wires as well as the bolts on the starter connectors at the starter. I once had a bad earth connection at the earth cable to the body/chassis which caused all kinds of problems.

 

[Spanky]

I suggest you check all earth wires as well as the bolts on the starter connectors at the starter. I once had a bad earth connection at the earth cable to the body/chassis which caused all kinds of problems.

Agreed. Good chance it's a bad/intermittent ground connection.

 

[kgosi_f30_340i]

Agreed. Good chance it's a bad/intermittent ground connection.

I’m gonna have to assume this is the issue because I really can’t find the reason everything is working is normal now. No issues since my last message and hadn’t switched on the car till today. Switched on with no issues and no extra discharge on the battery. Thanks for the help. @Solo Man and @Spanky

 

[sash]

I did take the battery in to battery centre and they tested health, charge and did a load test and all looks good.

When doing the load test, was it done just once? A good battery should be able to manage multiple load test before it drops. I have seen many test centre's do a single load test and say it's good, but on the second test it falls flat

 

[Mytfine]

When doing the load test, was it done just once? A good battery should be able to manage multiple load test before it drops. I have seen many test centre's do a single load test and say it's good, but on the second test it falls flat

This here

 

[kgosi_f30_340i]

When doing the load test, was it done just once? A good battery should be able to manage multiple load test before it drops. I have seen many test centre's do a single load test and say it's good, but on the second test it falls flat

It was done only once. But since I did a 24 hour monitor of the battery using Carly and it seems to be doing good. I will have to do another load test ASAP in that case and ensure it’s fine.

 

[Mytfine]

It was done only once. But since I did a 24 hour monitor of the battery using Carly and it seems to be doing good. I will have to do another load test ASAP in that case and ensure it’s fine.

Does your car park outside ? CCA reduces greatly at colder temps especially on a sub par battery.

 

[kgosi_f30_340i]

Does your car park outside ? CCA reduces greatly at colder temps especially on a sub par battery.

Nope parks in the garage. And now it’s not starting again. This seems like a battery load issue indeed. Will take it in again and see.

 

[Spanky]

Nope parks in the garage. And now it’s not starting again. This seems like a battery load issue indeed. Will take it in again and see.

Could still be either bud - did you actually tighten all the grounding points on the car? If not, this is still a possibility as vibrations will result in varying levels of electrical contact.

 

[Anees]

When doing the load test, was it done just once? A good battery should be able to manage multiple load test before it drops. I have seen many test centre's do a single load test and say it's good, but on the second test it falls flat

This

Experienced the same problems with the battery on the X3 and battery center said all is fine after one load test. Problem continued and I went back to the same battery center. They ended up replacing the battery for me after performing multiple tests

 

[Kyle]

You need a new battery man...

 

[kgosi_f30_340i]

You need a new battery man...

I tested the battery at 2 separate places and load tested 4x and the battery has 0 faults and holds voltage. There is definitely something else messed up that is just draining the battery on the car. Which really sucks.

 

[VinceM]

Did you check for inactive trackers?

(Sorry if was confirmed. didn’t read entire thread)


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