Come back from vacation, battery is dead

[DeutschRennfahrer]

I was only gone 4 days, but when I got back the battery was completely dead. The battery is less than a year old, and I bought it only a few months prior. Clearly something is remaining on after I shutoff the car. Any idea what this might be? Very frustrating to deal with.

[schobyb]

This happened to me a couple times. Now, if I leave it for more than a day or two, I put it on a battery tender. I have restored mine overnight with a battery tender and in a couple hours with a battery charger. Battery Tender is your friend with these cars.

[DeutschRennfahrer]

Good to know. I will get one and try it!

[WestCDA]

If it's the original battery, its almost 10 years old, which is more than due for replacement. It's already given you fair warning that it's on its way out - I'd put a new one in there before it dies on you when you are away from home ...

[DeutschRennfahrer]

How long does it take to recharge a dead z4 battery with a 12v battery tender? I've had it plugged in for almost 20 hours now and its still not even 80% charged.

[StickMon]

What WestCDA said.
Pop down to AutoZone and grab a new one.
You're probably charging a dead horse.

[fullerra]

Get yourself a volt meter. If after 48hrs or so on the charger it's still only reading 11 or so volts then one of the cells in the battery age dead, and it will never fully charge. A full battery with all functioning cells should read around 13 volts or so.

[DeutschRennfahrer]

Thanks guys. I ended up returning the battery tender and buying a new battery. I'm now back on the road and 180 dollars poorer.

[Incompatible]

Originally Posted by DeutschRennfahrer

Thanks guys. I ended up returning the battery tender and buying a new battery. I'm now back on the road and 180 dollars poorer.

10 years on the oem battery is great, very few last that long. $180 investment for years of peace of mind and reliability is cheap by any standard.

[elerner61]

Over the years I've found that a standard battery will last around 4 years in the Northeast in a garaged car. Is the life expectancy for an AGM battery known to be better/worse?

[DeutschRennfahrer]

I bought a new battery a few months ago but I am now having the same problem after I return from a trip; the battery is completely dead.

I have no idea what could possibly be staying on when I turn off the car, but clearly something is not properly shutting off and is draining the battery. What should I do?

[Clearancediver]

Check to see if your alternator is charging the battery....

[bamarider]

Originally Posted by DeutschRennfahrer

I bought a new battery a few months ago but I am now having the same problem after I return from a trip; the battery is completely dead.

I have no idea what could possibly be staying on when I turn off the car, but clearly something is not properly shutting off and is draining the battery. What should I do?

If you have access to a dc amp meter check the current on the battery with engine off. If more than 1-1.5 amp you have a problem with something not shutting off. You can start pulling fuses to find your problem.

[Jumbosock]

Originally Posted by DeutschRennfahrer

I bought a new battery a few months ago but I am now having the same problem after I return from a trip; the battery is completely dead.

I have no idea what could possibly be staying on when I turn off the car, but clearly something is not properly shutting off and is draining the battery. What should I do?

This is a very common issue with these cars. Mine won't last 2 days. I have never tried to find the culprit but I think it might be the stereo. If I sit in my car I can hear it fire up and do random stuff while the car is off. Incidentally, my Xterra does that same thing but doesn't drain the battery. I just keep it on a trickle charger but that's not a real fix.

[StickMon]

As soon as you do anything to "wake the car up", it will boot the nav system.
Like open a door, or boop the keyfob.
That's what you hear when you get in it but it's still off.
It'll eventually power down if you don't do anything else.

I have LEDs in my hamburgers. They glow dimly whenever the car is "awake".
Maybe if just as a test, pop a cheap LED in one of your hamburgers to see if the car ever goes to sleep.
Never timed it, but mine shut off after a minute or two.

[themenacedesigns]

I know this is an old thread but as a heads up for anyone experiencing dead battery after leaving their car sitting overnight or couple days I just experienced same problem with my 06 M roadster about 75k on clock.

Shop in VA did countless tests on the electrical system even got a new OEM battery which lasted maybe a week then back to dead after parking for more then 4-6 hours.

I had a thought that I do listen to my iphone music alot while driving so suggested they check the amplifier. Turns out my factory amplifier failed and wasn't turning off when the vehicle was turned off thus the parasitic draw killing the battery. Disconnected the amplifier and now no sound system but no more dead battery 8)

[RossBMWZseries]

Originally Posted by themenacedesigns

I know this is an old thread but as a heads up for anyone experiencing dead battery after leaving their car sitting overnight or couple days I just experienced same problem with my 06 M roadster about 75k on clock.

Shop in VA did countless tests on the electrical system even got a new OEM battery which lasted maybe a week then back to dead after parking for more then 4-6 hours.

I had a thought that I do listen to my iphone music alot while driving so suggested they check the amplifier. Turns out my factory amplifier failed and wasn't turning off when the vehicle was turned off thus the parasitic draw killing the battery. Disconnected the amplifier and now no sound system but no more dead battery 8)

Old thread I know but I'm dealing with the same thing in my 2006Z4M! Battery keeps dying after having replaced it about 4 times in the last 2 months. Diagnostic test by Indy shop indicated it's a dead NAVI unit that's draining the battery. They said it stays on while far is off and that I need to replace it. The guy didn't look so sure when he said that. This unit is $2,500 and I would hate to replace something that I don't even use just to stop the car from continue dying. I would specially hate it if the problem doesn't get fixed after spending that kind of money