Battery Dead....Won't Hold Charge

[tomsawyer]

05 4.4i w/ 60K

Hi Everyone, I realize that battery drains, vehicles won't start, etc have been discussed ad nauseam on this site but I figured I would throw my current dilemma into the mix.

For the last couple of years, I have had a battery drain. What happens is if I don't drive the vehicle for 2 days, the 3rd day it won't start. So I always made sure the truck was driven and I never ran into a problem until I went away for vacation (I never attached a trickle charger).

Finally, in November 2012, fed up after calling triple A a bunch of times, I took it to the dealer. I had an Interstate batter in there and the first thing the advisor tells me is they want to install a BMW battery. I ok it and sure enough they wait 3 days and the car won't start. So the tech goes thru the various procedures and cannot find anything. I guess he started unplugging and replugging, testing, etc and then the drain goes away. They let the car sit for 5 days, 2 separate times and the truck started both times on the 5th day.

I took the truck back and everything seemed to be fine. I even went on vacation, came back, truck started right up.

All of a sudden, this past Saturday, the truck wouldn't start. Put the key in and click click click. I have a battery pack and jump the truck and drive it for 2 hours. Come home, turn off, lock it and the next day it's dead, won't start. I jump it again but this time I get a trans failsafe prog error, the outside temp is showing minus 40 degrees and the gas tank gauge shows empty but I know the tank is full.

I drive to get a cup of coffee, turn truck off, get coffee, try to restart but its dead again. I jump it and drive it to my friend who's a mechanic, but not a BMW specialist. He did his tests and told me yesterday the battery is completely dead and won't even hold a charge.

What could all of a sudden have happened that the truck is completely dead - having gone from a 3 day drain to "repaired" (in quotes b/c we really never found out what was corrected) to now completely dead?

Thanks to all who answer.

[TerminatorX5]

so... when i n november 2012 the mechanic was unplugging things, somehow he fixed the problem... there is no record of what he had done? If I am not mistaken, the BMW warrants their repairs for 2 years and unlimited mileage, not sure if this applies to plain labor with no parts involved... on the other hand, battery is a part...

take car back to the dealer, and demand a new battery under warranty, have it installed, if the new battery is dead in couple of days, have them chase that gremlin again... I am sure it cost you a pretty penny first time around they chased it - that is one of the reasons they charge that premium as they include the warranty...

and try to find out, what was it, that the mechanic unplugged at the time and resolved the issue...

I would not stick my fingers into this issue as it should be under warranty, and the dealer will use any excuse to get out of warranty, claiming that you may have tampered with the car...

it is like the 2011 335 that i lease - lilght bulb burns - i take it to a dealer, not because i can't fix it, but because it is their problem...


on a separate note, if for whatever reason you insist on doing the gremlin chasing yourself, check to see if the car goes to sleep in the first place... after the last activity on the car, 16 minutes later most modules go to sleep, whether the car is locked or not, doors open or not... another minute or two, the very few modules that are not asleep, go to sleep too... only alarm module should be awake, as it keep monitoring the entry points, tilt and motion sensors...

if the car is not asleep, something keeps it awake... check all fuses in the glove compartment and the trunk area - check with an OhmMeter to be on the safe side... a blown fuse may create an alternative path for the electricity to flow, thus keeping the car awake... check the fuses even if the car goes to sleep...

but... let the dealer deal with it first... at least the battery should be replaced free of charge, even Wal-Mart has some kind of battery warranty....

[epdarks]

Have you checked the voltage output of the alternator?

[ukrcan]

yeah, faulty alternator would be my guess too...

[tomsawyer]

Forgive me if I say things incorrectly as I'm not very technical when it comes to cars.

Darks - I'm not sure if my friend tested the alternator. I think he didn't b/c the battery won't even hold a charge. He told me he drove the truck all over, came back to his shop and was dead. He then took out the battery to bench charge/test and it won't hold.

Term - I know exactly what you are saying about the dealer. I'll have to call the advisor and discuss w/ him. He happens to be best friends w/ my mechanic and is a good dude. I'll see what he says.

One thing I didn't mention in the original post is I have that Sirius radio module that BMW had back in the day installed which allows you to run Sirius through the stock radio via an FM channel when you have the separate Sirius radio/cradle. I spoke to the BMW tech that installed it (he's a friend too). When I told him about the battery dead issue, he told me to get rid of the Sirius radio (even though he installed it). He told me to by pass it and plug the radio plug back into the radio and bypass the Sirius module as he thinks its possible the module may be keeping the radio awake. He also wired the Sirius radio cradle to the cigarette lighter and told me to disconnect that as well - then he told me to do the amp test on the battery, but like I said the batt is dead.

So either I go get a battery and do it myself or do what Terminator suggests.

[TerminatorX5]

alternator should definetely be on the check list but the OPs car would die while parked for extended (or not so extended) period of times that suggests that something is draining the battery - no matter how well it is charged up, it will eventually drain... of course, a poorly charged batery will hold less charge to go around in the frist place...

[tomsawyer]

Terminator - Back to your original question....back in November, they really never found the true cause of the issue. Like I said, they confirmed there was a draw. But after going through their procedure, whatever that was, they found that the draw disappeared. I was told they allowed the car to go to sleep and it was drawing 40 milliamps (I think that's what they said) which is the number they were looking for. They reconfirmed 2 more times and then, they let the car sit for 5 days, 2 separate times and it fired right up each time. So what I paid for was the battery, the time to put in the battery, and 1 hr diagnostic. My friend swore the tech put in like 10 hrs but they didn't bill me b/c they felt bad they really never found the root cause. Still the bill was like $500 and change (I realize it could've been much higher).

Can an alternator test be done on a car with a totally dead battery?

Also, how plausible do you think its that Sirius setup?

[bcredliner]

First step is to take it to the dealer and exercise the warranty on the battery unless you don't believe your tech.

In your post you said the battery won't take a charge. If that is the case the alternator could be working just fine. If the battery has a dead short you might as well have the terminals connected to dog do do. This issue could be the same issue as last time or be connected to the alternator but until you have a good battery I see no reason to start checking any other branch on the electrical tree.

[TerminatorX5]

bc is right - you need a good battery to do anything electrical... unfortunately, the fault in the car can render the new battery no good - then you get a replacement battery... happened to my E39 several years ago...

as far as the sirius and the cradle - are they the OE parts? there is an OE sirius receiver that is installed in the trunk, next to the BM53 (or is it BM54 radio?) if you have the nav in the spot where the TV module would go otherwise... the OE sirius module would use the CD changer connectors...

now, if the sirius is aftermarket - then it must go... as well as anything else you had installed aftermarket - the way the GM is programmed, that if there is a certain level of electrical draw in the system, the GM will NOT let the car go to sleep:

so, if you have completely stock setup, after 16 minutes the GM sends out a telegram on the bus, telling the other modules to go to sleep... the modules start the shut down process, each module has its own prosedure - within a minute the modules are asleep...

if you have something drawing juice from the car (depending on where the draw is), as if some accessory is tapped into a GM-monitored circuit, then the GM will not send the sleeping telegram, and the car will remain awake... the target amperage of 40mA sounds right, i think the nominal value is 35 mA, if the amperage is higher, then - no sleepy time... this is one of the main reasons that i mind my amperage and which circuit i am tapping my mods...

if the aftermarket sirius is fed from the radio power supply, then the radio reports back the excess draw, and the GM keep the system active... The whole process is much more complicated on the electrical level, but in essense this is what is happening...

remove the sirius, lets see what happens...

[tomsawyer]

Thanks Term - Again, forgive me if I don't explain correctly but I'll do my best.

My understanding of the Sirius situation is this - I had purchased a Sirius radio. It was the one where the Sirius radio had that cassette thingy which you would put into the cassette player so you could play and hear the Sirius radio. I have navigation so I couldn't use the cassette.

My BMW tech friend told me he had an original, made by BMW, Sirius module. My understanding is it is plug and play. He mounted this Sirius module next to the BMW radio module that's in the spare tire comparment. He unplugged the plug from the bmw radio and plugged it into the Sirius module - then he plugged the sirius module into the BMW radio module. Again, he said this BMW radio module is next to the spare tire somewhere.

For the Sirius cradle, he mounted that on the driver's side vent (on the left side of the instrument cluster), but the cradle needs power for the Sirius radio. So, he ran the wires underneath the dash and tapped into the cigarette lighter for power.

That's my understanding of that set up and there are absolutely no other aftermarket components in the truck. Everything is stock.