Battery is drained even while driving

[danielfb]

My newly bought Z3 drains its new battery, even while driving. I drove it after a long ride (1h) and then I stopped to open the hood. All fine until I tried to start it again. I couldn't. I brought me second car and made a bridge between batteries. I could start it. The I took a ride and slowly all the warnings in the dash lights turned on till the car stopped (I had to use the hand brake)
The strange thing is that usually when you have an alternator problem the battery light is on, but in this case it is not.
Any guess what could it be?

 

[t-tony]

The battery is failed. Where are you located Daniel?

Tony.

 

[danielfb]

.

The battery is failed. Where are you located Daniel?

Tony.

Switzerland.
It's a new battery! Although the cheapest one available...
I'll try to get a good one before taking the Z3 to the mechanic.

 

[Stevo7682]

Charge your new battery re install get a hold of a volt meter fire it up check if alternator is OK and charging.
I know you said battery light not on but that doesn't mean it is OK.
Stephen.

 

[Duncodin]

When my z3 drained the battery I found that the passenger seat fore/back switch was stuck in the back position so the motor was continually straining to slide the seat back.

 

[danielfb]

Charge your new battery re install get a hold of a volt meter fire it up check if alternator is OK and charging.
I know you said battery light not on but that doesn't mean it is OK.
Stephen.

Thanks for your answer, it's now connected to a battery tender. To test with voltimeter, I start the car and voltage should go above 13, right?

 

[danielfb]

When my z3 drained the battery I found that the passenger seat fore/back switch was stuck in the back position so the motor was continually straining to slide the seat back.

Good tip, will check on this. I had a problem with another car, where the switch to adjust the mirrors was also draining the battery if left on.

 

[t-tony]

At idle the volts should be 13.8 -14.0. With headlights, wipers, Fans and HRW on the voltage will drop. When you increase the fast idle to around 1800 - 2,000 rpm the volts should go back up to around 14.0 again. Did the battery light come on before starting the engine and go out after starting? If the battery light didn't come on then possibly the alternator is shot.

Tony.

 

[danielfb]

At idle the volts should be 13.8 -14.0. With headlights, wipers, Fans and HRW on the voltage will drop. When you increase the fast idle to around 1800 - 2,000 rpm the volts should go back up to around 14.0 again. Did the battery light come on before starting the engine and go out after starting? If the battery light didn't come on then possibly the alternator is shot.

Tony.

It's getting interesting...
The battery light doesn't come at all on start. Voltage of battery is 12.5. Voltage at idle is 13, giving some gas it reaches 13.5.
Could it be a case of a zombie alternator? Not dead, not alive?

 

[t-tony]

There should be a 12 v live feed to the alternator, if it isn't there the battery light won't be lit and the alternator will not charge. Check fuses.

Tony.

 

[danielfb]

I think there's a leak problem. This evening, before checking the fuses, I checked the battery voltage. It was 10v compared to 12.5 this morning. I will let the battery charging all night long, and tomorrow will check the fuses. I have read about a stubborn fuse 31...

 

[t-tony]

You could disconnect the earth lead from the battery and then check the voltage across the battery terminals in the morning. Voltage should be about the same. Did you check the battery for distilled water. I have known a new battery come "dry" before now.

Tony.

 

[danielfb]

You could disconnect the earth lead from the battery and then check the voltage across the battery terminals in the morning. Voltage should be about the same. Did you check the battery for distilled water. I have known a new battery come "dry" before now.

Tony.

Yes will do that tomorrow. The battery was sold as 'ready to be used'. When I shake it I here some liquid inside.
Interestingly I have read this thread:

Parasitic drain on battery solved

Heads up Testing my zed. Patched this info together after many hours of research, trial and error. To the chase. Draw associated with Fuse 31 EWS System, central locking, etcetera, yours may vary with model. Was drawing 125 milliamps. Dropped to 30 ma in sleep mode after fix. This is about what...

www.zroadster.org

It basically says that if you don't lock your car, or close your windows, it doesn't enter the so called 'sleep mode' and it keeps using the battery until it's empty.
Well, I don't remember neither me nor my wife having ever locked any of our cars before. Even if windows were left opened it was always fine!
I fear the battery is damaged after being fully drained due to leaving it unlocked the first day

 

[danielfb]

Day 3
Dear diary,
I installed the battery, fully charged after an overnight charge. It measured 12.5 V
I checked the Amperes being pulled from the battery with doors opened or closed. Both 30mA, which seems to be fine.
Still no battery light.
With a battery charged the car starts fine.
Once started the battery shows 13v
Next step is to fully charge the batter and hope I can make it to the workshop.

 

[Kenhayes247]

I keep my car garaged, it's always unlocked, for a few months it had no doors fitted, the battery was still connected and I even left the key in the ignition (switched off) of course. My battery did not go flat, not even after a few weeks of not being run.

 

[Kenhayes247]

Given that the car is draining the battery whilst driving it does seem to point towards a faulty battery/a fault with the alternator etc. That said a recent faulty starter motor was managing to drain my battery within hours sometimes less even though it turned the engine over fine. I changed it and also cleaned up all the cars earthing points and all has been fine since.

 

[danielfb]

Day 4
Yesterday afternoon, after giving the battery a full charge, I made it to the mechanic; 15 mins drive.
As soon as I told him my story, he quickly identified the alternator as the culprit. He asked me to touch it. It was burning!
He said that an alternator running too hot indicates something is wrong with it.
This explains why when you just start the car, and the alternator is still cold, it gives some voltage, but as it gets hotter it stops working (When he checked the voltage it was giving nothing).
According to him, it could partly be due to car being stopped for too long, or simply it was about time to replace it; the car has only 60k miles but it's 25 years old.
Lesson learnt: If your battery is behaving like if there's a poltergeist living in it, check your alternator. If it's too hot -> Not good. Time to replace it.
Hopefully this is the end of the story. It this really fixes the issue I'll post another entry to close the thread.

 

[Rudyrov]

Sounds like a bad rectifier in the alternator, you have a sharp mechanic!

 

[t-tony]

I suspect there is something else wrong here. A vehicle running on a fully charged battery using nothing more than indicators and the ignition system should be able to run for way more than a 15 minute journey, it should be able to run for a couple of hours at least.

Tony.

 

[Duncodin]

I suspect there is something else wrong here. A vehicle running on a fully charged battery using nothing more than indicators and the ignition system should be able to run for way more than a 15 minute journey, it should be able to run for a couple of hours at least.

Tony.

If the alternator is getting hot then that heat comes from somewhere. Maybe friction. But maybe a short circuit inside thats turning the alternator into a heating element that consumes electricity.