On New Year's Eve I tried opening the boot of my 2005 MC Convertible (purchased used last May) to retrieve an item. It seemed locked and after several tries unlocking doors, etc I determined that the battery was dead. My husband and I went on with our plans (taking the other car). When we got home, we tried jumping the car. The MC did not start, the lights flashed, there were clicking noises and the top and windows partially dropped. We decided that we would take out the battery and get it tested at the nearest Auto shop the next day (the dealer was to be closed the next three days).


When we took out the battery we noticed it was a 2008 production date, we were working under the assumption that the battery was a 2005 battery and due for replacement so I was a little more concerned about it being a 2008 battery. We took it to the auto shop as planned and the battery was, in fact, dead. They offered to charge it for us, we opted for the slow, full trickle charge. Because it was New Years day the auto shop had altered hours. we were able to pick up the battery that afternoon before they closed but by the time we drove home and then reinstalled the battery, the shop was closed. Good news was that the recharged battery started the car just fine so the next morning we went back to the auto shop and had the battery retested along with the starter and alternator. The starter and alternator tested just fine, the battery still had a full charge so that was good but after the car was shut off there was a 1.5 Amp drain on the battery (labeled as *suspect* on the handy print out they give you).


Of course throughout all of this I had been reading lots of threads here on NAM and learned that it may take awhile for the onboard computer to fully shut down so I decided to go back last weekend and let the car sit for awhile (just over one hour) and then have them test the battery for a drain. The MC tested with a 0.3 Amp battery drain after sitting for one hour. The printout reports that as *normal* but I have read a thread on here that a 0.03 Amp drain is normal after a one hour rest. I have only installed the Aux wire (the one that plugs into the back of the stereo). As far as we can see the original owner did not install any aftermarket mods but I am sure there are things that could be done that I wouldnt necessarily notice.


My questions are...is this worrisome? Are there any aftermarket mods that are known to cause a 0.3 Amp drain? Is a 0.3 Amp drain nothing to even worry about? Am I likely to notice stalling or rough starting before the battery dies again (if that is even a risk)?


I am due for an oil and fluids change soon (next month or so). If no one can provide reasonable answers, I will have the dealership check it out. It just seems that dealerships have (reportedly on NAM) had trouble locating causes of parasitic battery drains and just tends to blame them on aftermarket mods (though no one has accused my particular dealer of that here on NAM). I dont want to pay for diagnostics if it is likely they wont find a problem or if it isnt a big of enough drain to be a problem. Thanks for any suggestions!

 

Interesting post - I was planning on asking the same question. Put my 2002 MCS up for the winter back in October. New battery/fully charged when parked in heated garage. Failed to hook up float charger - was on another vehicle. Needed to move the MCS last night - no power, nothing. On charger so I'll be able to determine battery condition/current draw this evening. Interested in replies.

Kevin

 

Do you have a car alarm??
With keyless entry there will always be some drain when a car sit, since the radio/computer will always be listening. Not sure what the normal range is...somebody surly will chime in.
Talking to many people, and in my personal experance, I will tell you, our cars must br driven pretty regularly to matain a full charge...I've been told 8000-10,000 miles per year min....the fact that the car was totaly dead...no lights, no window dips, till you tried to jumpstart it, IMO points towards some draw draing the battery in a short time. I'd keep on eye on it for a bit...ps pumps, cooling fans, lights, etc have all been known to get stuck on.

 

The oem batterys are generly considred to be 24-36 month batts....so the fact you had a newer one in your car is not superising.. Many 05's also got new batterys under a recall of sorts...so having the newer battery in the car is no big deal.

 

Thanks for the responses so far. below I have address the issues brought up by others.

firenewt--I drive my car at least a few (2-3) times a week. I will admit to not motoring as much since the weather has turned nasty...not wanting to dirty her up when it is nearly impossible to clean her. Since I have had this battery issue, I have driven her at least every other day, letting her warm up for at least 5 minutes before initially starting out for the day. My garage is not heated but completly enclosed. The temps have been around 10-30 degrees F.

ZippyNH--I do not have a car alarm (as far as I know). The key does have the remote fob with the door unlock/ door lock/ boot unlock buttons. The key was out of the ignition for the second batter drain test (I would believe for the first test as that is my normal habit but I wont swear to it). I did have the key in my pocket and I was standing by the front of the car--could that be enough *talking* to cause a 0.3 Amp drain?

My hope is that since I purchased the car used in May (and I know for a fact it had been sitting in the lot for a few months) is that the battery was never fully charged since I have owned the car and that a combination of me not driving too much in the few weeks preceding the dead battery coupled with the low temps (10-30 F) caused the fully dead battery that.

I am very thankful that it happened at home and when I had access to another car. My concern is that the 0.3 Amp draw is not normal and may cause the battery to die again in a not-so-convenient situation. I am hoping someone may have some input into whether or not a 0.3 Amp draw is normal or if it is something to be concerned about. Again, many thanks for the responses so far. Please keep them coming!

 

Just chiming in that there is a thread on NAM about how long your OEM battery lasted for, and many posters were over 6 years, so I'm not sure I buy the 24-36 month typical lifetime quoted above.

 

I managed to get 4 yrs out of mine....but several scources like WhirRoofRadio, and motoringfile says or eludes that the construction and rating of the battery says it is 24-36....it is definateiy not the typical 60 month battery, let alone the 72....so the shorter life span quoted seems pretty accurate as so many do fail shortly before/after the warrenty expires...happens to be 36 months.....

 

I've got an 05 with the original battery.

The 1.5 amp draw is LIKELY normal. All cars have SOME parasitic drain to keep the Computers memories, CLOCK , Radio presets and other things.

If you think it's excessive you can get an ampmeter in the positive line and monitor the draw and start pulling fuses one at a time and see where the draw is and how much each draw is.

 

What is your voltage at the battery when the car is idling? The ground strap cause some issues similar to this for me a year ago when the metal started to corrode.

Also, do you shut off the fans and stereo or do you let them shut off with the car? Are you leaving anything plugged into the 12v socket (I've had a ghost that'll supply power to those items randomly even after the car is off)

 

The battery drain should not exceed 50ma (.050 amps) after all the systems go to sleep. the IPOD interface supplied by MINI is known to cause a battery drainage problem! MINI has a TSB addressing this issue.

If this is the case then the Radio is suspect. disconnect the fuse while monitoring the current draw; this must be done after the system goes to sleep and without opening the door as this may wake the system up again.

BMW's test the oxygen sensors after the car is shut off; the ECM will command a high current flow through the oxygen sensor heater and then look for an appropriate response from the O2; this behavior is by design.

Good luck and please advise when the concern is resolved!

 

frenchie--I was wondering about opening the door to pop the hood. I dont love the idea of leaving the hood popped and the car sitting in the auto store lot for an hour. May have to get a battery tester so I can just do the tests myself. (i suspect a trip to the store tomorrow!) Will be able to do the fuse tests without feeling like I am wasting autoguys time too.

I have the AUX plug/wire not the ipod interface. Does that make a difference with the BMW TSB?


Motor ON--as far as we can tell the connections looked clean. The battery connections were cleaned just to be sure of those. I usually have the heat or air off when I turn the car off. The radio is on but the MP3 player is off or unplugged. I will definitely confirm all of that before the next test but those are my usual habits.


bad venge, zippyNH and veggievet--thanks for the input in battery life. I have done lots of reading since the original problem and found that the MINI factory's battery life is varied indeed! It panicked me a bit at first as I had been thinking the whole night that it was probably an older battery and seeing it was newer concerned me. Given a little time I realized that the battery had probably done a lot of sitting around this spring and I dont drive around lots so I calmed down about that. Still, it is good to have others input!



Thanks to everyone that took the time to reply. Keep the suggestions coming. I will gladly keep trying things until an answer is found and keep you all posted!

 

UPdate: I couldnt't find the proper tester (the one that tests loads and can be left attached for monitoring) at several stores after the last update. So I decided to just keep a really good eye on the battery charge with the tester that I had (the one that is on the trickle charger). It is currently at about 70 - 80 % (depending on how cold the temperature is). I had an appointment for an oil change so I explained the situation to the dealer and asked them to do whatever looking and stuff that they would do for free. They said that the current charge on the battery was good...everything looked ok and the dead battery was probably just from a combination of the battery sitting for awhile (while at the dealer's waiting to be purchased), the cold temps and me not driving a lot (thereby not keeping the battery charged). My current plan is to just keep an eye on it by testing it weekly or so.


Thanks again to all who replied!

 

Why not just buy a Battery Tender and hardwire it to the battery, then just plug it in when you get home, you'll always have a fully charged battery, no problema.....

 

smurfette.. now 11 years later... did you ever solve the battery drain issue?

 

Solve, no. Learn to mostly work with, yes. As long as I drive once a week or two in colder weather and once a month in warmer weather it starts up. I keep the radio powered off and the climate control off before turning off the car. I have my battery tender if I let things go a bit too long like this past winter after I was attacked by two Rottweilers and didnt drive for 6 weeks. Both the 2005 Convertible (Smurfette, battery about 5 years old) and the 2013 Roadster (Banana, battery about 3 years old) were dead after that. But after charging both are maintaining a charge still.