When the weather gets cold, my car has a history of freaking out. It also has a long history of eating batteries... I am on battery #4 and the current battery is less than a year old! With 80k miles, I recently had the spark plugs, ignition coils and wiring harness replaced by an indep mech because it was driving and idling rough.

A couple of weeks after those repairs, I went to drive the car home from work and on start up got an erroneous headlight out warning indicator -- the dash indicator came on but every light was actually on.

The next time I went to drive it, I came out to a dead battery with flickering interior lights. When I popped the hood, we could still hear a solenoid softly activating under the fuse box about every 90 seconds. We jumped the car and took it back to same mech who could not find anything but a low battery. Whatever solenoid had drained the battery stopped, but it was activating when the car was OFF!

They charged up the battery, but now I am having a problem with the driver's side headlight on start up. It does not come on immediately and may flash on and off a few times before finally deciding to stay on.

To add to this problem history, the driver's headlight was replaced after being hit by a mail truck last May.

Any ideas appreciated!

 

Has anyone performed a Battery Drain Test on the car? Even if it takes a day or two to get whatever component to act up and starting draining the battery, it's better than constantly going through batteries.
Drains are hard on Alternators as well since you can stress the ALTN. on a Low Battery once the vehicle's been jump started to get it running again.
One more note, on many cars that are fairly new, once the battery voltage level gets low enough from the "real" drain that is causing it, you can get 'new' drains from ECU's that run normally OKAY on correct battery voltage with the car off, since the ECU's are being badly affected by the falling voltage and if you zero in on that false ECU and its output or devices that it runs, you can get fooled into thinking it was your battery drain cause. It's frustrating but true/misleading of a diagnostic path.


Your best bet is working with a fully charged battery, and don't let it get below 11.5 volts or so when diagnosing. Once voltages go below 11 volts, other electronics in the vehicle can be affected.

 

DIY ?

https://www.popularmechanics.com/car...attery-drains/

 

 

Just take a pic of the fuse box. When you start pulling fuses, do not reinstall them until you find the one with the current draw. You can then reinstall the fuses that you pulled and concentrate on the circuit causing the problem.

Have you had any aftermarket electrical items installed. If so, I would start there.

 

No, this is not sound advise depending on how complex of a CAN BUS system the car, or any car has. Let me explain why.
If you pull the fuse on one of the ECU's that is a Terminating Resistor end of the CAN BUS, you can wake up multiple ECUs, causing the meter reading to go up and totally confuse the diagnostic path, since you just took the whole Can Bus down with the loss of one of the ECU's that has the all important Terminating Resistor in it for the BUS. On some cars, once the Medium Speed Bus goes down ,you get side affects like Lights flashing or other warnings that the Engineers tossed in as a helpful hint to tell you that the Medium Speed Bus is down.
I don't know if MINI does that type of thing, but other Car Manufs do when they have multiple Bus lines on a car, medium and High Speed.


So, here is another method for new cars that works, but I'm the first to admit I'm not as comfortable in using as I am of the older method of an Amp Meter in line/series and pulling fuses. Also, it's more expensive since it requires two tools...
Instead, you use an Inductive Amp Meter that goes around one of the main battery cables, and you use a Multi-Meter in Voltage Mode to watch the voltage drop of an active circuit/draw. The Amp Meter doesn't disturb any connections and the use of the Voltage Meter doesn't require any fuses to be pulled until you're really sure you've found that active draw.
http://testmeterpro.com/parasitic-dr...-a-multimeter/


This Method is now the only factory approved one for finding Battery Drains for several manufs. I'm not thrilled with it since you would need a second person to watch the Inductive Amp Clamp that's stuck at where ever the battery is on the vehicle, unlike the older In-Line Amp meter method where you could add 10 or even 30 foot test leads to keep the meter right next to you in the car/vehicle instead of clamped around a main battery cable.
I've had cars where I just bumped or moved the interior of a vehicle the right way and saw a change in the meter right in front of me, letting me know that my issue was very nearby like a sticking relay or other electrical part. Also, the fuses aren't always easy to get to with test leads/probes, so if they're buried in a dash and almost out of reach, trying to hold two probes on the top of a mini-type fuse can be trying as you're checking that voltage drop of a circuit with your meter....

 

So, are we risking permanent to systems/components by randomly pulling fuses. If yes, then I agree that the approved method should be explored. If not, then I would think that in the OPs case, the parasitic drain would be in the 1-2 amp range, while awakening modules should only be in the milliamp range, except lights and horns, and those can be easily seen.

I guess it comes down to what do you have to lose in giving it a try, as long as pulling fuses won't cause additional problems.

 

 

Unfortunately my knowledge of canbus. Bcm, Ecu, etc is not nearly good enough. I think it is great that guys like you take the time to comment and educate. I admit that I am a bit of an old school backyard mechanic but I am always trying to enhance my understanding of newer systems. My suggestions are simply things that I would try. Perhaps they may be a waist of time but I really hate having someone else work on my vehicles.