car doesnt keep battery charge

[14''BBS]

My 318is has been acting weird lately, the battery doesnt stay charged. I went to the bank the other day and when i came out it would struggle to start as if the battery was low, i managed to get it fired up and ever since than if i turn it off it wont have enough juice. The battery was purchased a 2 months ago probably. Parasitic draw? Any ideas? Also im sure i have a code for coil pack 1 .

To drive it i have it on a battery starter/trickle but i cant turn it off whenever i go somewhere.. friggin blows. I thought alternator but i heard it wont drive without a good alty
Feedback much appreciated.

[george graves]

What the voltage with the car running?

You really should own a multimeter. If not, take it to Autozone/Kargen/Pepboys, and they will test the charging system for you for free.

[e30s50dan]

Bad battery or alt.

[bmwman91]

Sounds like the charging system isn't working properly. Maybe the regulator on the alternator is shot? Either that or the battery is no good.

[george graves]

Bad battery or alt.

Or parasitic draw.

The central locking unit can go crazy. And it will suck some amps - so will the interior light relay. And ABS IIRC.

So just to say Bad battery, or Alt - it's not as helpful as giving some pointers to find the problem! ;D

[shameson]

Seems more like a charging issue than a draw, with how quickly it's dying. Maybe have the alternator checked?

I'm not expert but I believe you can test draw by disconnecting the negative cable on the battery and using a multimeter you can check the mA on the negative post when the car is off and in sleep mode. Anything over like 20 mA means there's a draw. You can pull fuses to check which one lowers the reading.

[IRON-E]

My brother seems to be having a similar issue, to the point of disconnecting his battery every time the car will be sitting for longer than 5 mins.
Yesterday, the car decided to just shut off and leave him stranded. Knowing the symptoms that the car is going through, he disconnected the battery for 10 mind and the car fired up again.......... what could this draw be?

Sorry OP, just hoping to get some help with my brother's 318i as well.

[IRON-E]

Bump

[kwill22]

if unplugging the battery saves it then yea there's a serious draw somewhere. the battery could also be bad because its supposed to be able to support a certain load while its not being charged for a certain amount of time before dropping too low and being that it dies within minutes id say theres a serious draw. the battery could use a good charge once the draw problem is solved to verify that its good.

[benz-tech]

The voltage regulator can pull the battery down as well as not charge it when running, although the former is less common. Cheaper than an entire alternator as well.

[14''BBS]

My engine bay started to make a crazy metal on metal noise the same day i did my timing chain tensioner so i was tripping. Turns out it was a loose bolt from within the slternator thst backed out and was hitting the rotating blade. Im thinking that possibly the screw was allowing the alternator to run low voltage? I screwed it back in and it was starting fine but a bit sluggish. Maybe ill pull the regulator to see if the brushes are in decent shape.

[Stevoyayaya3]

The voltage regulator can pull the battery down as well as not charge it when running, although the former is less common. Cheaper than an entire alternator as well.

This^^ I had my 318is in the shop for 6 months with no luck. I got it back and changed the voltage regulator and problem solved. Just make sure to get the correct one for your alternator. Lol now I'm having a cooling problem :/

[14''BBS]

Its not a bmw if it doesnt have cooling issues! Ahhh i hate shops, never again for me. Ive noticed if your not dropping stacks you dont get note worthy service.. my research has told me that the reason my code is up aswell as my shitty battery sitch is most likely the voltage regulator makes sense, since coils are new and spark is low? Plus my radio makes crazy noises sometimes.

I have a 90a bosch alt originally from an audi/vw 1.8t. It looks really good in regards to fitment but we'll see. A regulator is only like 30 bucks but more amps are always good.