[steve@codemybimmer]

Recently, my battery light has been coming on in the mornings when my engine is cold. It's usually about 2C in the mornings here and when I start the car, I will get the battery light.

Weird thing is, if I let the engine warm up a bit and start the car again, I will not get the warning and the car works as normal. I don't seem to hear any differences in the crank and it sounds the same as before. Sometimes, I can go one 2-3 days without seeing the message at all.

Would I have an issue with the alternator maybe? I called my mechanic and he mentions that it might even be the intelligent battery sensor. I had the starter replaced recently as it was completely dead and would not start.


Would this be a major concern?

[tibra1]

Could be battery dying..it makes perfect sense that after it charges the light wouldnt come back on..as it sits thru the night it is discharging hence you get the light in the morn..then again it could be sensor..you need to test the battery

How many yrs on this battery?

[steve@codemybimmer]

Originally Posted by tibra1

Battery is prolly dying..it makes perfect sense that after it charges the light wouldnt come back on..as it sits thru the night it is discharging hence you get the light in the morn

How many yrs on this battery?

I'm pretty certain it's more than 4 years. I'm the second owner of this car. At this point, how long would you say I have before the car will need a jump start?

Also, I hear you need coding to replace the batteries on the E90.

[tibra1]

Originally Posted by Aritaurus

I'm pretty certain it's more than 4 years. I'm the second owner of this car. At this point, how long would you say I have before the car will need a jump start?

Also, I hear you need coding to replace the batteries on the E90.

You want to avoid having to jump these cars..the electrical systems are VERY sensitive..if your battery is more than 4 yrs old I would replace it. Batteries get worse as it gets colder

Its an easy DIY..but yes u need to register (code) the new battery. Do you have a BT tool?..You can register w/ it..

IMO every late model BMW owner should have a BT tool

[cole92]

 
           Battery            Approximate           Average Cell
           Voltage          State-of-charge       Specific Gravity
 
            12.66                100%                  1.265
            12.45                 75%                   1.225
            12.24                 50%                   1.190
            12.06                 25%                   1.155
            11.89                  0%                   1.120
 
 Note:  If the temperature of the electrolyte is below 70 degrees F, then
 add .012 volts (12 millivolts) per degree below 70 degrees F.
 
      D.  If the battery's state-of-charge is at 75% or higher, then load
 test the battery by one of the following methods:
 
           1.  Turn the headlights on high beam for six minutes,
           2.  Disable the ignition and turn the engine over for 15
                 seconds with the starter motor,
           3.  With a battery load tester, apply a load equal to one half
                 of the Cold Cranking Amp (CCA) rating of the battery, or
           4.  With a battery load tester, apply a load equal to one half
                 the Original Equipment Manufacturer (OEM) cranking amp
                 specification.
 
 DURING the load test, the voltage on a good battery will NOT drop below
 9.7 volts with the electrolyte at 80 degrees F.  (If the electrolyte
 is above 80 degrees, add .1 volt for every 10 degrees above 80 until you
 reach 100 degrees.  If below 80 degrees, subtract .1 volt for every 10
 degrees until 40 degrees.)  After the load is removed, the battery should
 "bounce back" to the 50% state-of-charge level or above.  If the battery
 drops below minimum test voltage, does not bounce back or will not start
 the engine, then you should replace it.  If it passes this test, you
 should recharge your battery to restore it to peak performance.

The other option is, if you have an auto meter battery tester that can remove a surface charge and test the battery, it's much easier than doing the above. Have someone from advanced auto or autozone check it.

[tibra1]

Or buy a BT tool and you can do this, including registering a new battery..and checking for and clearing codes and logging data..etc etc

The BT tool pays for itself.. buying one used is your best bet

[username604]

your car is an '06... time for a new battery? or just listen to whatever tibra1 says, he knows his stuff

[witeagle]

someone please explain why you need to code a new battery? What do you mean by 'code'.

btw - what is a BT tool?

I also just found this link regarding the ability for the car to re-learn on it's on:
http://www.justanswer.com/bmw/4qd9b-...2007-335i.html

[JamesM3M5]

Originally Posted by witeagle

someone please explain why you need to code a new battery? What do you mean by 'code'.

btw - what is a BT tool?

I also just found this link regarding the ability for the car to re-learn on it's on:
http://www.justanswer.com/bmw/4qd9b-...2007-335i.html

The DME controls charging voltage on nearly all modern cars. As the battery ages, the alternator output voltage is increased by the DME to help charge an old battery. If you do not register the new battery in the DME, it can overcharge a new battery and kill it within weeks or months.

Sounds like you have an aging battery that can't hold voltage over cold nights. Best to test it first, check alternator output, and most likely you will just need a new battery.

[cole92]

No doubt the BT tool works and you should have it, was merely giving suggestion on how to check it without buying anything.

[fdriller9]

Forget the BT tool. Get a OBDII to USB cable off eBay.

I got an OBDII to serial R232 cable off eBay for $37 shipped. Then a $10 R232 to USB adapter off amazon.

I have the BT tool as well but I rarely use it since I got my other cable.

You can also do coding with the eBay cable.

The reason why you're seeing the message on a cold start and no after restarting is for 2 reasons:

1) As temperature drops, the performance of a battery decreases. It's ability to hold a charge is negatively affected.
2) A cold engine is harder to turn over than a warm engine.

If you are on your original battery, then forget the testing, it needs to be replaced.

[striderg3]

Originally Posted by *********

Forget the BT tool. Get a OBDII to USB cable off eBay.

I got an OBDII to serial R232 cable off eBay for $37 shipped. Then a $10 R232 to USB adapter off amazon.

I have the BT tool as well but I rarely use it since I got my other cable.

You can also do coding with the eBay cable.

The reason why you're seeing the message on a cold start and no after restarting is for 2 reasons:

1) As temperature drops, the performance of a battery decreases. It's ability to hold a charge is negatively affected.
2) A cold engine is harder to turn over than a warm engine.

If you are on your original battery, then forget the testing, it needs to be replaced.

just replaced my 325i's battery with a new one. the previous battery has acid or some deposit all over it and has left its mark in the battery bay. more acid im guessing.

haven't driven it yet but I turned it on for a minute or so after connecting terminals and the dash has no lights or anything but after a few hours went back and inserted key just to set the clock and the battery sign is up in the screen again. what gives? it has to be registered?? or what? it is more powerful than the previous battery so im guessing it needs to be programmed to that batteries specs? wtf kind of a system do these people deploy in these cars... utter uselessness from a consumers perspective. anyways your help is appreciated, thanks.

http://www.canadiantire.ca/AST/brows...85_ViewDetails

[DPritchett]

[QUOTE=Aritaurus;10782452]Recently, my battery light has been coming on in the mornings when my engine is cold. It's usually about 2C in the mornings here and when I start the car, I will get the battery light.

Weird thing is, if I let the engine warm up a bit and start the car again, I will not get the warning and the car works as normal. I don't seem to hear any differences in the crank and it sounds the same as before. Sometimes, I can go one 2-3 days without seeing the message at all.

Would I have an issue with the alternator maybe? I called my mechanic and he mentions that it might even be the intelligent battery sensor. I had the starter replaced recently as it was completely dead and would not start.


Would this be a major concern?[/QUO

YMMV - but in September, I got a low battery warning one morning when I drove the car for the first time in about a week. It went away and didn't return, so I thought it was just due to the car sitting for a week.

The next morning my son and I drove to Georgia for the Petite Lemans race, and on race day, when we got ready to leave, the battery was dead ... barely enough juice to make the interior lights come on when we opened the door. We had no choice to to get a jump ... which made warning lights and check control messages light up my dash like a Christmas tree (which went away when we shut the car down and restarted)..

We drove home the next day, and I dropped the car off at the dealer to have the battery checked the next day. They replaced it and there have been no problems since.

[striderg3]

registered my new battery and its all good now