[hardr85]

First I want to thank everyone for all of their answers to posts, I have learned so much about my car!

I have a 2006 330i, I bought it about 4 months ago with 93k miles on it. We had a cold snap a few weeks ago, it go down to about 10 degrees. I go to start the car, no crank, the all the lights light up. I jump start it, get it going,, tranny in limp mode. Eventually it all lined out. Got on forum and started looking. Came to the conclusion it was alternator, battery, or IBS. I acessed the hidden menu to monitor voltage. My findings are as follows.

The battery is about 6 months old, it is an interstate battery. The guy I bought it from said it was registered. I believe it was put in by a local indy who is a master mechanic who used to work for a dealership, so I am assuming it was coded if it was needed.

When I accessed the codes, I had already been running errands for work, the voltage was a constant 13.7.

The following day, I decided to disconnect the IBS and monitor the voltage.

After car sat 18 hours, it was 35 degrees the voltage was 12.

Started car it went down to 9 something, up to 12 when it started, then about 10 seconds, went to 14.9.

Drove 3 miles to store, when I stopped it was 11.5, left it running, got coffee, came back in 3 or 4 minutes, it was 10.5. The hedlights, heater, and radio were on the whole time.

The next night, I re-connected the IBS. The car had sat for about 18 hours.

Before start 11.9

Went up to 13.8 with headlights on after start

Stopped for gas, headlights off at idle 12.2 went down to 11.7 after idle setteled in.

When i drove it went back to 13.7

I drove about 15 miles, when I shut it off it went to 12.4

It was the same for the drive home.

I am pretty sure its not the alternator, the voltage seems about right without IBS.

The battery is a bit low at 12V, is the IBS working properly based on these voltage numbers? Most of what I have read is it should go up to 14.7 or so, then back down, is the IBS keeping the voltage lower because it is a newer battery?

I do have an erratic idle issue, it has had one since I bought it, that is why I got a pretty good deal on it. The previous owner took great care of the outside, but didnt do a damn thing for preventive maintenance. I think I have most of that solved, but that is another story. The point is, it seems now as if the car ran better without the IBS with the voltage up around 14.7. It was smoother, especially the power band on hard acceleration. I am pretty sure I have answered my own question, but I wanted input, and any other ideas or anything else I should consider. If it is tye IBS, should I replace that and see if the battery will take and hold a charge? Please advise, any and all input is needed.

Thanks everyone again for any help, I hope I will be able to help others as I learn from my experiences.

[ctuna]

I would try a ctek3300 first or better battery tender first.
Also Interstate battery's have a 3 year warranty.
It seem odd that the running voltage would ever be under
14.5 which is about normal for any car.
Seem like if its working without the IBS the IBS is unnecessary
crap.
The voltage will drop on start on any battery but if the start is
quick and not labored its and indication the battery is OK.
If you are not using the car much or are only going on short
trips you need a battery tender. Also locking the car makes
it go to sleep quickly and reduces the static battery drain.
Do you have the right size battery ?
I have a MTP 49/H8 in mine no problems but it doesn't
get cold around here.

[hardr85]

I will check the battery size tonight. The start seems a little labored, the decline seems to have been gradual so it harder to tell, but it seems to take one extra turn of the starter.

I started to think battery when my steering wheel lock became labored sounding. About two months ago, I removed the lock, cleaned and greased it, and it was great. That is actualy when I noticed the difference in the sound. It had started sounding more labored as of late, after I cleaned it, it a quick zip sound. Now it is slow sound, sometimes I dont hear it, and I get the lock symbol. I started wondering if it is a battery issue.

[hardr85]

I would not be suprised if the battery is run down. In the last four months I have changed the thermostat, water pump, valve cover gasket, eccentric shaft sensor, the oil housing gasket, 1 o2 sensor, the plugs, and three coils.

When I got it the ccvv was just a piece or random rubber hose, when I went to remove valve cover the bolts were less than finger tight, there was about 5 quarts of black oil in it, the oil level sensor did not work, still doesent. I have a new one, still does not work, but I have a new harness I have yet to install.

A few times, when I have left work, I drive about 10 miles, get to a stop light, yellow temp shows up, then red, the I hear the fan start up, then it goes away, even with a new thermostat and coolant pump, and coolant temp sensor, and oil/coolant temp sensor. I didn't want to mention all of these other issues, cause my first post was long enough, but do you think all of this could related to battery/voltage issues? I had so many vaccuum leaks I assumed the rough idle was yet another leak, when the idle stumbles and car surges, the voltage drops and comes back up, is the surge a result of the voltage, or the oppisite? Which came first, the chicken or the egg?

[hardr85]

I mention the thermostat and coolant pump because I have done two flushes without car being on a charger, multiple starts, and multiple short trips. I have put quite a strain on battery, if it is not charging prroperly, I am not suprised it is low. Should I leave the IBS unplugged for a while to let battery get a good charge? Woukd that hurt anything?

[ctuna]

When the car is awake it draws .5 amps
and if you are working on it as you describe it will be more.
When BMW programs a car they put it on a regulated
power supply.
Basically these cars are battery hogs.
I would get a charger and top off your battery, then see what
happens .
If you haven't already got tender get a ctek3300 or better.
If its charging at around 14.5 that is pretty normal for almost
any car I don't see how it could hurt the car but the hocus
pocus with battery lasting longer might not work . The thing is I
don't think it works anyway. I got 8 years out of my E46 battery
with no IBS the one in my current car was only good for 6.
Also I top off my battery with a charger about once a month
cause its a low use car.


the following link tells you something about it.


http://www.google.com/url?sa=t&rct=j...,d.cGU&cad=rja

[hardr85]

I will get it charged today and see what happens, thank you for your help.

I have had IBS disconnected for two days now. When I drive the car the first time of the day, it runs at 14.8 to 15, but when I drive it again about 1.5 hours later, it runs at 13.2 to 13.4 for the rest of the day. Could it be the regulator?