Increased battery discharge 2012 135i

[whostorm05]

Hi Peeps...

I recently purchased a used 2012 135i - 6700 miles or so - from a used porsche dealership. The car has been modded by the previous owner - an unknown number of things but at the very least suspension, exhaust and I believe an aftermarket downpipe. There is a BMW Can Tool plugged into the obd port i'm assuming to clear the codes associated with a down pipe.

Current problem is that several weeks ago I got an 'Increased battery discharge' warning. I had been taking several short trips so I wrote it off as being that. I then went on a 20-30 minute trip and started the car the next day and the error was still present. In the past few weeks there have been once or twice where the warning wasn't present, but for the most part it has been present each time I started the car. I noticed keyless access doesn't work when I get the warning.

I've checked everything I can think of to check which might be drawing current when the car is off and can't find anything.

I need to take the car in, but I'm a bit concerned what they are going to say about the can tool and the exhaust mods. They 'should' have to prove that one of the mods is causing the increased battery discharge in order for my warranty to not cover repairs, but I'm still concerned.

Any suggestions to hopefully make this an easier trip to the dealer?

[smellthebeans]

Could be the bus hanging off the port. I have avoided the N54 out of preference for natural aspiration so, I am no expert on tunes & mods.

1. I recently purchased a 128i sight unseen at auction. Previous owner attempted to install an aftermarket sound system. After I removed all of the wiring and put everything back to stock the discharge warning went away. Could there be somethign hanging off the head unit?

2. Could the battery have been replaced & not properly registered?

[whostorm05]

Hi Beans,

I've tried unplugging the can tool after turning off the car to see if perhaps that was it. I've still had the error the next day.

I'll take a look at the battery and see if I can tell if it's been replaced.

Everything with the radio/nav/alarm looks stock. It was fine for around 2 weeks after I first bought the car.

[whostorm05]

Looks like leaving the BMS CAN tool plugged in 24x7 is what was draining the battery. I unplugged it totally for the weekend and the battery discharge warning went away. My SES light did come on but that probably just confirms the fact that there is an aftermarket downpipe installed. I'll have to disable auto delete and plug the tool back in and check the codes later.

[Dackelone]

Why not measure the voltage across the battery terminals? Your battery should have at least 12.8 volts with the car off. And with the car running close to 14 volts. (both DC volts) You can also check for AC volts across the battery terminals... you should have less than 1volt ac. AC voltage(at the battery) is a sign that your alternator(rectifier/brushes) is going bad.

[Mr Kleen]

Bumping an old thread.

2 days ago I noticed a whining noise in the car, similar to the sound a stereo amp makes when it was a dirty ground. The difference is that the sound did not vary directly with engine RPM like you would expect from a bad amp ground.

I opened the hood while the car was stopped, engine off but electrical system on. I heard the sound but then it stopped. I haven't been able to repeat this behavior though.

Some BMW friends suggested I check the coolant level as it could be the electrical water pump making the noise. I checked the coolant and it was low. I topped off the coolant but the odd sound persisted last night.

This morning I when I left for work I got the "increased battery discharge" warning. I have no electrical system "mods" and haven't done anything since installing my JB4 almost 2 years ago. I dread taking it to a dealer here in Germany...

[MGallop]

Originally Posted by Mr Kleen

This morning I when I left for work I got the "increased battery discharge" warning. I have no electrical system "mods" and haven't done anything since installing my JB4 almost 2 years ago. I dread taking it to a dealer here in Germany...

I took mine to the dealer the other day for "Increased Battery Discharge" error as well. I left the JB4 installed, but turned it to map0. Thinking this was just a dead battery deal, I wasn't too worried about the tune in there.

They ended up doing a voltage check and found several low voltage faults.
They found Fuse 11 removed draw. Fuse 11 powers DME, which led them to finding the tune.
They stopped the check once they got there and have requested for me to remove the tune and retest to check the draw.

My car for a while now has had a couple long crank issues, but always turned over, so didn't worry much about it. This was also before i got any battery discharge errors.

then recently all of a sudden i was getting the battery discharge error everyday for about a week. I then scheduled my appointment to go in on the following monday. Well having the car sit over the weekend cause the battery to completely drain. didnt even crank when i tried to start her up.

I was able to jump the car and bring in to dealership - and since then, i have had no current issues with the battery discharge error.

I wonder if when they were exploring - they did something to fix the error... no clue what they could have done, but so far so good.
I plan on taking off the tune and bringing it back in, but so strange how the error message is gone now.

[Dackelone]

Could be your IBS...

[NorthernDancer]

#1. first of all, when you have a battery issue, the 1st thing you should do is charge the battery overnight. Use a good high quality automatic battery charger of 1.5 to 10 amp. I'd recommend the Battery Tender or CTEK or even Schumacher. If your battery is old, you drive short distances, its freezing cold, you may have to continue using it once or twice a week.
#2. buy a cheap digital voltmeter, $10 - $15 & learn how to use it.
#3. I'd also recommend the Innova Equus 3721, less than $20

Here in the frozen North, battery voltage can drop as low as 11.9 volts and still start my car. My day to day battery voltages usually are between 12.3 and 12.5 volts (surface charge eliminated). I may not drive a car for a few days so I'm often "topping up" my batteries. NEVER had a problem & I have 2 Bimmers. My other daily driver has a cigarette lighter which is hot all the time so I leave the Equus plugged in at all times. I'll walk past the car and can look in thru the windshield and see its battery voltage & know ahead of time if it needs attention.

[Adam135]

After getting the "increased battery discharge" message, BMW diagnosed it as a faulty battery and it has been fine ever since.

[m_thompson]

Originally Posted by Adam135

After getting the "increased battery discharge" message, BMW diagnosed it as a faulty battery and it has been fine ever since.

Same with our 328xiT when it was only a year old, so the battery was replaced. An hour later the "increased battery discharge" message was back. The dealer replaced the IBS and it was OK for 5 years.

Recently the clock needed resetting if the car wasn't driven every day, so time for another battery. The battery was replaced, and an hour later we started getting the "increased battery discharge" message. The dealer is replacing the IBS again, under the extended warranty.

[MGallop]

My battery voltage when the car is on is around 14.25 - when off it drops to 12.25.
Was able to jump the battery again today via under the hood positive terminal.

I have to take off my tune and bring back to dealer to scope out some more.
I am thinking its either a battery gone bad / IBS / or alternator is shot.

Hopefully they don't give me any BS about the tune previously being there that caused this :\

[Dackelone]

[NorthernDancer]

Wow, what a great video Dack thanks. (Christmas night 23:42 EST)

[ASPEC135i]

Originally Posted by m_thompson

Same with our 328xiT when it was only a year old, so the battery was replaced. An hour later the "increased battery discharge" message was back. The dealer replaced the IBS and it was OK for 5 years.

Recently the clock needed resetting if the car wasn't driven every day, so time for another battery. The battery was replaced, and an hour later we started getting the "increased battery discharge" message. The dealer is replacing the IBS again, under the extended warranty.

Lol that it because they replaced a year old battery for you for the wrong reason. Nice!

[m_thompson]

Originally Posted by ASPEC135i

Lol that it because they replaced a year old battery for you for the wrong reason. Nice!

Well, the first time the battery and IBS were replaced under warranty, so that was OK with me. The second time the battery really was dying because of age and they replaced the IBS for free because they broke it during installation.