Parasitic Battery Drain e53 - Page 9

Makus · #81 10-30-2019, 03:18 PM

Quote:

Originally Posted by andrewwynn

If the current draw drops to 40ma after it goes to sleep you don't have a parasitic draw.

Check the vBat at the battery when you attempt to start. If vBat stays high the problem is likely either the B+ terminal loose or a ground or a connection like the starter.

You can measure vBat at the cig lighter as that is always live and takes a different path to the front of the car than the start/alternator cable.

The other thing you should check is the current draw of the starter which should be about 200-250A. If you have a peak reading multimeter you can measure the voltage drop from the B+ under the hood to the pos of the sig lighter. IIRC you multiply the voltage drop by 300 to get amps to the starter eg. 0.75v= 225A.

When a starter begins to fail it will take more and more current up to double. When that happens you lose double the voltage on the wiring and you get slow turning starter it will "feel like" the battery is low. I've seen a dozen cases of somebody replace both battery and alternator when the starter was the actual problem.

A loose ground strap will have the same problem. If it's loose it can have a 4v drop across the connection and suddenly 12v is 8 and a car won't start

it might make sense, while I was charging the battery and it had 13V and I decided to try to start the car and the value dropped to 12.5V or even lower and there was no power to start the car, only at about 13.4V the starter managed to start without a problem

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andrewwynn · #82 10-30-2019, 03:58 PM

What did the battery drop to while trying?

A couple people on XO have recently come across a loose connection at the B+ under the hood. The schematic is wrong where it shows the cable is continuous and has a tap to the alternator: it actually is discontinuous and is connected on both sides of the firewall and can get loose. It will give the symptom of a dead battery or starter but with the odd exception of normal resting voltage of 12.4 or so.

Makus · #83 10-30-2019, 04:11 PM

values that I gave were at rest without start, if I understood you correctly, is it good to check the fastening of the wires, is there nothing or loose? I am wondering grounding because if I have low values (.05-.07) in sleeping mode which could not be able to discharge the battery so quickly, as I wrote, when the battery is fully charged or I run on cables, the car has no problem with starting but after a few hours something will drain the battery

andrewwynn · #84 10-30-2019, 04:14 PM

You are saying something will drain the battery but you are also saying the battery has a resetting voltage of 12.4 which is fully charged. Numbers like 13.2 are only right after charging that's not a resting charge.

Your symptoms sound like either a loose connection somewhere can be power or ground side or a defective battery.

Fifty150hs · #85 10-30-2019, 04:44 PM

Pull the fuse for your Nav system and see what happens.

Bmwe5320023.0 · #86 11-08-2021, 12:59 PM

My turn to figure out a drain.
It's between 2-3 amps for the first 16 minutes, then drops down to about 600-700 mA
I have aftermarket audio system that I installed but I disconnected it.
I also installed a remote starter which I will try disconnecting.
Tried pulling all the fuses and relays in the trunk, no luck yet.
Next are fuses in the glove compartment

Fifty150hs · #87 11-08-2021, 01:07 PM

Quote:

Originally Posted by Bmwe5320023.0

My turn to figure out a drain.
It's between 2-3 amps for the first 16 minutes, then drops down to about 600-700 mA
I have aftermarket audio system that I installed but I disconnected it.
I also installed a remote starter which I will try disconnecting.
Tried pulling all the fuses and relays in the trunk, no luck yet.
Next are fuses in the glove compartment

Do you have a TCU? It is often the source of parasitic drain. If you have one try pulling the fuse. Check your FSU. That's also a common source of parasitic drain.

andrewwynn · #88 11-08-2021, 01:21 PM

Did you start with the hedge hog? It's the usual suspect.

crystalworks · #89 11-08-2021, 01:34 PM

Quote:

Originally Posted by andrewwynn

Did you start with the hedge hog? It's the usual suspect.

My IHKA went dark on a road trip to Houston on Friday... ordering a new FSR hedgehog today.

Glad the outside temp was 70f as when it occurred (lasted 20-30 minutes), per usual, it goes to full heat @ full blast. I was concerned my feet were going to be burned as I was unable to use cruise due to traffic on IH10 (stupid never ending construction). And lowering the windows, while making it tolerable, creates a vacuum that sucks air through the vents at an even higher rate. Talk about hot feet

Positive note... I know for sure I have ZERO air bubbles in my cooling system.

Bmwe5320023.0 · #90 11-08-2021, 05:02 PM

I dont think I have TCU.
I changed my front FSU its brand new, maybe the rear one...
Also thinking maybe EWS is drawing power since I deleted EWS module and have a fuse on EWS connector to shirt pin 1 and pin 2. Not sure how much remote starter is supposed to draw normally. I also installed a front and rear camera, but didn't think it'd draw much when in sleep mode.
I've had some kind of parasitic draw since I bought this car a couple of years ago but never actually measured it.
I will get to the bottom of it now and post results

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