Rear Window Defogger- Bad Battery?

[mccand]

The only problem I've ever had with my car is the "low battery" warning light coming on. And the "even lower"/ car picture on lift. If the engine was off, the "low battery light" would consistently come on after about 30 seconds or less of radio playing at normal volumes.

This happened prior to my last service (July 2014). The dealer said the battery was low on charge, I wasn't driving enough, and they recharged it. (I was driving it every day, so this was BS, but I took the car back anyway)

So its still going on, and getting worse, to the point where the "car picture on the lift" warning comes up often (but not all the time).

Furthermore, I've noticed that the "touch" entry now sometimes does not work, and (worst of all), the rear defogger does not work. (even when the low battery warning is *not* present). Note that the defogger button lights up on the dash. Just no defogging. (and ONCE it *did* start to defog just towards the end of a 30 minute drive, so I suppose you could call it intermittent).

Could these all be related, and I just need a new battery? Is there some sort of sensor that disables key functions that are high power draw when the battery voltage is low?

I have an appointment with the dealer at the end of the month, but wanted to do some legwork...

thanks!

[miro2296]

Originally Posted by mccand

The only problem I've ever had with my car is the "low battery" warning light coming on. And the "even lower"/ car picture on lift. If the engine was off, the "low battery light" would consistently come on after about 30 seconds or less of radio playing at normal volumes.

This happened prior to my last service (July 2014). The dealer said the battery was low on charge, I wasn't driving enough, and they recharged it. (I was driving it every day, so this was BS, but I took the car back anyway)

So its still going on, and getting worse, to the point where the "car picture on the lift" warning comes up often (but not all the time).

Furthermore, I've noticed that the "touch" entry now sometimes does not work, and (worst of all), the rear defogger does not work. (even when the low battery warning is *not* present). Note that the defogger button lights up on the dash. Just no defogging. (and ONCE it *did* start to defog just towards the end of a 30 minute drive, so I suppose you could call it intermittent).

Could these all be related, and I just need a new battery? Is there some sort of sensor that disables key functions that are high power draw when the battery voltage is low?

I have an appointment with the dealer at the end of the month, but wanted to do some legwork...

thanks!

Yea i had similiar behavior on mine. I had to replace the battery.

[MightyMouseTech]

You say you drive it every day, but how far? Battery takes about 30 mins of driving to recharge after a start.

[mccand]

About 30 minutes commute each way each day. Glad to hear the defogger may be related to battery, miro2296. Thanks for reply!

[mccand]

(also, FWIW, (and I said this in an earlier post dealing with my low battery warnings), if a car is required to be driven 1/2 hr every day to avoid a low battery light, that is not a very robust design IMHO.

My '88 Honda CRX can go 2 months of sitting and fire right up...

I sure hope that when I get the new battery, the car is a little more forgiving of needing to be driven every day..

[MightyMouseTech]

Originally Posted by mccand

(also, FWIW, (and I said this in an earlier post dealing with my low battery warnings), if a car is required to be driven 1/2 hr every day to avoid a low battery light, that is not a very robust design IMHO.

You are misquoting me. It should be driven 30 mins with EACH START. Not per day.

[PaulMcA]

Originally Posted by mccand

(also, FWIW, (and I said this in an earlier post dealing with my low battery warnings), if a car is required to be driven 1/2 hr every day to avoid a low battery light, that is not a very robust design IMHO.

My '88 Honda CRX can go 2 months of sitting and fire right up...

I sure hope that when I get the new battery, the car is a little more forgiving of needing to be driven every day..

You're '88 Honda CRX probably had 10% of the electrical requirement and equipment as standard on a SatNav, HiFi, etc. equipped 1M

[mccand]

True (on the Honda). And I apologize for the misquote. But does anyone have issues where the low battery light comes on when they leave the radio running for more than about 30 seconds? Or is it just that I got a bad battery? (or do the batteries last only 3 years)?

[portine9]

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[PaulMcA]

End of Nov '14 I had a warning light and message saying battery discharge was greater than expected and also got the 'Service Ramp' indicator light on when starting the car.
Dealer took the car for 24 hours, did a full battery charge, discharge and check and came back to me saying that the battery could be replaced at the cost of > £230 (UK Sterling), or suggested in all likelihood taking a longer run and using the car for more than a short journey (30 mins) would fix the issue. And it did
They also suggested a trickle charger if I don't use the car for long periods.

[MightyMouseTech]

Originally Posted by mccand

True (on the Honda). And I apologize for the misquote. But does anyone have issues where the low battery light comes on when they leave the radio running for more than about 30 seconds? Or is it just that I got a bad battery? (or do the batteries last only 3 years)?

If your battery is low on charge, it does not take very long before you get warnings. Are you sure you are listening to the radio in "accessory" mode and not in the "on" position? If you have it in the "on" position, the entire car is awake. Heated seats, rear defrost, blower motor will all be on sucking an incredible amount of current. Will deplete a battery in no time.

My golden rule. If you are in the car, the engine is on. Period.

[RS375]

Hook a decent CTEK battery conditioner up to your battery to see if it can be revived.

[mccand]

Hmm.. I was thinking/hoping the dealer would pay for the replacement of the battery...(assuming it is in fact in need of replacement).

Is there a way to put it in "accessory" mode? It may have been in "on" position. I clearly knew to do this with the old school key (like in my Honda for example), but not with the push button....

I just ordered a CTEK based on a bit of research... thanks for the suggestion! I wonder if I should do the "condition" thing.. maybe I'll see what dealer says first, to see if I can/should get a new battery for free from them.. Then use conditioner if I don't drive for, say, a week or so...

If they are going to charge me for a new battery, I'd go the condition & maintain with CTEK route until the battery gets worse. The low voltage thing comes on, but it doesn't ever seem to have trouble turning over or anything...

[Dackelone]

Originally Posted by mccand

Hmm.. I was thinking/hoping the dealer would pay for the replacement of the battery...(assuming it is in fact in need of replacement).

Is there a way to put it in "accessory" mode? It may have been in "on" position. I clearly knew to do this with the old school key (like in my Honda for example), but not with the push button....

I just ordered a CTEK based on a bit of research... thanks for the suggestion! I wonder if I should do the "condition" thing.. maybe I'll see what dealer says first, to see if I can/should get a new battery for free from them.. Then use conditioner if I don't drive for, say, a week or so...

If they are going to charge me for a new battery, I'd go the condition & maintain with CTEK route until the battery gets worse. The low voltage thing comes on, but it doesn't ever seem to have trouble turning over or anything...

Just buy a new battery and call it a day! (don't forget to have it coded!) Why spend money on a CTEK and take the chance of getting stranded somewhere. ?

PS: You did have your battery cable recall done right?

[mccand]

umm... whats the battery cable recall?
Also, any word on an "accessory" mode for radio on while car off?

[EldRick]

A) "umm... whats the battery cable recall?"
Ask your dealer.

B) RTFM. "Radio" mode does not activate all the high-drain secondary stuff, like climate control and set-heaters. Push the start button Once, without using the clutch pedal.

[RS375]

Originally Posted by Dackelone

Just buy a new battery and call it a day! (don't forget to have it coded!) Why spend money on a CTEK and take the chance of getting stranded somewhere. ?

PS: You did have your battery cable recall done right?

Dack,

I appreciate the point about getting stranded but even so a CTEK is a good call even if the OP does end up with a new battery.

It's just maintenance for the battery and will help keep it in tip top condition.

Mine's not a daily driver so in general it gets hooked up to the CTEK if I haven't given it a run for a week or so.

I did a similar thing with my last car and the battery was tested at 3 years and reported to be in excellent condition.

They're expensive things to replace and at the heart of all things electrical in our cars, so a little TLC goes a long way. I just treat it as part of the maintenenace programme.

[mccand]

good to know on that 'radio mode'! Thanks!

[EldRick]

You could also search the forum for "battery cable recall" Your 1M needs it if you haven't had it done, and if the cable is has gone high-resistance, it could be the source of your battery discharge (and a risk of a fire in the trunk).

[M3 Adjuster]

Originally Posted by mccand

(also, FWIW, (and I said this in an earlier post dealing with my low battery warnings), if a car is required to be driven 1/2 hr every day to avoid a low battery light, that is not a very robust design IMHO.

My '88 Honda CRX can go 2 months of sitting and fire right up...

I sure hope that when I get the new battery, the car is a little more forgiving of needing to be driven every day..

Is your 2011 Bmw the same as your Honda? No. This is a very stupid comment

[Em/1]

Originally Posted by M3 Adjuster

Is your 2011 Bmw the same as your Honda? No. This is a very stupid comment

I don't think it is that stupid. I'll stick my neck out and point out that I just replaced my battery in 2004 Jag XJ8 at 100,000 only because it made me nervous. I'm getting same kind of readings as the OP when in accessory mode even right after a 50 mile mostly highway 40 minute ride and I think from what I have seen in other sources (Roundel) that BMW should be doing a better job with the electronics.

[M3 Adjuster]

Originally Posted by Em/1

I don't think it is that stupid. I'll stick my neck out and point out that I just replaced my battery in 2004 Jag XJ8 at 100,000 only because it made me nervous. I'm getting same kind of readings as the OP when in accessory mode even right after a 50 mile mostly highway 40 minute ride and I think from what I have seen in other sources (Roundel) that BMW should be doing a better job with the electronics.

It does in that they are apples and oranges in many ways.

manufacturer, engine size, alternator size, battery size, and most importantly, the # of parasitic devices. don't know about you.. but most 1988 Hondas didn't have NAV systems, 12 speaker stereo systems with integral subwoofers under the seats, a hard drive, comfort access, bluetooth, and that's assuming the 80s vehicle has halfway modern creature comforts like heated seated seats and multiple defrosters for windows and mirrors. An 88 BMW had some items like those.. but not an 88 Honda.

It's absolutely ridiculous to compare the power requirements between vehicles made 20 years apart, as if 20 years of technology didn't occur.

Ever sit in your newer BMW for a few minutes after you turn the engine off?

Did you know that Bluetooth is still on? I have had my car take a call for me when it is in the garage and I was in my home!
Did you know that your iPhone can still be charging via USB?
Did you know that the stereo will play for 20 minutes before it turns off?
Did you know that the ignition circuitry is still energized including the push button remaining lit?
Did you know that the Angel Eyes remain ON until the driver's side door is opened?

How about comfort access... this system certainly is going to draw some current waiting for the owner to return. The OP has even mentioned that " touch access" doesn't work when he returns. That's because the only way this system can work is that a low power radio is on waiting for the owner to turn on so that it can wake up the car, and unlock the doors, and flash the lights, turn on the angel eyes and the rear taillights, and happily chirp a Hello beep.. (wow... that's a lot of power draw before the door even opened and the interior light came on! right? )

Ever notice once you get out and close the door..? hang around for about 3-5 minutes and listen to the whirring that goes on several minutes after the vehicle goes off.. and wait and see how long it takes for the push to start button to go out.

Using some of these features for even a short period of time with the engine off will have a serious effect on an already weak battery, and the great likelihood is that many of them are likely in use, along with many others. With multiple amplifiers and subwoofers, even playing the stereo at moderate volume for a few minutes after shutoff will eat into the reserve of your battery.

Originally Posted by mccand

umm... whats the battery cable recall?
Also, any word on an "accessory" mode for radio on while car off?

Originally Posted by EldRick

A) "umm... whats the battery cable recall?"
Ask your dealer.

B) RTFM. "Radio" mode does not activate all the high-drain secondary stuff, like climate control and set-heaters. Push the start button Once, without using the clutch pedal.

I'll see your RTFM and raise you one. Here is how I get in and turn on the "radio " mode.

1- Open door.
2- Push radio knob button to turn radio on. HEY LOOK MA! I didn't even hit the Start button!




OP. As an an FYI. When a vehicle battery is low...



a number of bad things can happen...



1- you may see any number of odd or random errors.. or odd lights on the dash... Defrost...airbag system lights.. check lights.. seat belt system etc.. basically ANY system circuit can show an error
2- vehicle headlights may dim or go out
3- vehicle subwoofers will not operate
4- vehicle radio will not operate
5- you can deplete and eventually kill your battery
6- you can damage your vehicle charging system (alternator, diodes, voltage regulators, starter, ecus, )
7- the vehicle may not idle properly and will stumble and eventually die at idle
8- you could blow up your motor.

What if the item getting a weak/intermittent/wacky brownout sort of power is the ENGINE ECU. If the vehicle brain can't think clearly... then it's not going to meter air/fuel ratios properly or even react to knock sensors) . Go out hot rodding with a worn down charging system, and the motor could go KABOOM.

Any, of the above items can occur on a vehicle that has a battery that still can have enough charge to turn over and start the vehicle. So. to answer your original question... could the multiple electrical issues you are having (no comfort access... no rear defroster... and.. rear defroster working at the end of a long drive) be the result of a weak battery? YES.