Red Battery symbol, then abs dsc please help

[jfoj]

Originally Posted by bcredliner

Upallnight is correct that a car will run based on the alternator output only. I agree the primary function of the battery is to start the engine. However, the current needed to keep the vehicle running and power the electrical systems still comes through the battery not directly to the electrical systems. What electrical systems are connected directly to the output of the alternator?

Vehicles are not all created equally, but there is something call Voltage drop that need to be taken into consideration AND keep in mind here, we are discussing BMW's. Our friends the Germans tend to do things a bit differntly then the rest of the world. Just because you may think you understand how a BMW is built does not mean you understand how the electrical system works.

The E53 and many other BMW's connect many of the electrical loads directly or very close to the battery, this does not mean the battery is meant to run or power the vehicle for extended periods of time, the Alternator is the PRIMARY DC power source for most modern vehicles.

BMW has the BST or ballistic battery cable that can and does go bad, but the purpose of this BST cable it to shed the vehicle load in case of an accident and reduce a fire hazard due to electrical problems.

But not all vehicles have connections directly at the battery. Many vehicle have load centers and/or larger fuse and relay centers that may or may not be located near the battery depending on the vehicle design.

So for someone to continue to state that the the vehicles loads are powered by the battery, this is flat wrong. I am not sure where this was learned or how this idea came about, but it clearly needs to be revisited.

The alternators primary purpose is not to be a battery charger. Until this concept can be understood, there will be no forward progress.

[jfoj]

Originally Posted by dabenthusiast

Sorry to see argument on this post.

This morning I am going to get the x5 towed to my house. I tested at terminals yesterday and got a 10v read.

When I get it to my house I will charge it and take it and measure volts again.

After that go to autozone and check it.

After that remove alternator and take it to get checked..

Not buying any parts until late I do get my car at my house because it's to hard to do test in another city without my garage.

Alot of the info has helped me.
I'll get back once my car is at my house and battery has charged.

No arguments, just people that do not understand or want to understand!

10 Volts at the battery or where every you measured is BAD.

A fully charged 12 Volt battery should have a terminal Voltage of 12.6 Volts.

Just because the batter has 12.6 Volts does not mean it is a good battery.

A battery can have a surface charge that is greater than 12.6 Volts, but this can quickly be removed by turning the headlights on for 30-60 seconds, then let the battery rest.

Until a battery is properly charged and tested, you have no idea what shape it is in.

Problems as mentioned, could be with loose or corroded terminals, a bad BST cable and even a bad alternator.

Keep in mind that some of these vehicles also have bad engine to body grounds as well.

If you have a battery charger that claims the battery is 100% charged, you cannot use this 100% value to consider the battery any good. The battery needs to be tested with a load tester and/or a resistive/capacitive battery tester. I prefer both.

A poor mans load test is to monitor the battery terminal Voltage on a fully charged batter, turn the headlights on and if the battery drops below 12.2 Volts, I would likely condemn the battery, but always best to have a proper test preformed.

[StephenVA]

Originally Posted by jfoj

.... Trader4 He was a real PITA and in case you have not noticed he deleted all of his posts a week ago or so from what I saw. He was a real PITA that offered nothing much to the forum members that were looking for help.

No loss. He really was a PITA that did not offer any help just whining about this part or that one and at BMW in general.

[jfoj]

Originally Posted by StephenVA

No loss. He really was a PITA that did not offer any help just whining about this part or that one and at BMW in general.

Thanks, we can at least agree on this point!

[Helihover]

Originally Posted by upallnight

Never claimed to be an expert in the automotive field. The only person that is making that claim on this forum is YOU.

The Youtube video was just to show that you can operate a car without a battery.

My statement was that the car runs off both the battery and alternator, not just one or the other.

The radio in my X and other cars operates just fine with the engine off and just running on the 12 volts Battery, so does the lights and the windshield wipers if I turn them on.

Are you by any chance related to Trader4. Or are you Trader4 but with a new log in?

Funny how I asked this same question almost two years ago and you ALL were on the other side of the fence!!!! Terminators car stopped running while he was driving. The battery came loose. I told you guys that the car should have stayed running, yet everyone insisted "bmws" won't because there is too much "electrical stuff". I even offered to try this on my own X, but YOU, upallnight, got me so nervous to try it explaining that there are current spikes and what not that alternator can not correct so you would take a chance of damaging components. So which one is it? Will your BMW X5 run without a battery installed?

[StephenVA]

Always!!!!

[StephenVA]

NEVER remove a battery connection when the engine is running. You will not like the results of the surge damage when reconnecting it. Modules will fail, electrical components will go off the deep end. Can it be done and not have any issues? Yes, but why take the chance? THis "test" was a short cut way back in the 60's left over from post war vehicles with generators.

Loose power connections have shorted out more electrical components than anything else in history. (An assumption on my part. No actual data collected...)

Regarding a vehicle that dies when the battery is disconnected: A good electrical system SHOULD have kept it running. But who knows what failed at the same time as the disconnect? The Regulator? The main module? The ground wire? Who knows? Maybe the alternator/wiring was DEAD/shorted before the disconnect.....

[Helihover]

Originally Posted by StephenVA

NEVER remove a battery connection when the engine is running. You will not like the results of the surge damage when reconnecting it. Modules will fail, electrical components will go off the deep end. Can it be done and not have any issues? Yes, but why take the chance? THis "test" was a short cut way back in the 60's left over from post war vehicles with generators.

Regarding a vehicle that dies when the battery is disconnected: A good electrical system SHOULD have kept it running. But who knows what failed at the same time as the disconnect? The Regulator? The main module? The ground wire? Who knows? Maybe the alternator was DEAD before the disconnect.....

It was stated that the connection at the battery came loose. Once tighten all was well from what I remember.

I thought the car should have kept running too.

[jfoj]

The battery dampens and filters the alternator output.

One thing that most modern vehicles do is the DME/ECU can and will kill spark and fuel if the input Voltage gets too high to protect the DME/ECU and other modules in the car in the case of a high Voltage swing. Usually 17-19 Volts it the trip point for most vehicle. No idea the exact value for BMW and I am not interesting in finding out on any of my cars.

You can arc weld with 120-200 Amps and as mentioned it is not a wise test to disconnect the battery on a modern vehicle for testing. Without the battery as a static load and filter, the alternator can do some funny things. Even filtering out AC ripple that can high peak to peak Voltages.

A $20 Voltmeter or using the Hidden OBC Menu to access the Voltage and display it on the dashboard is all that is needed. Charging and starting systems are really easy to trouble shoot as long as the EWS does not get in the way.

Learn how to use a Multimeter/Voltmeter and learn how to perform Voltage Drop testing and you can correct the majority of problems that creep up. I also use a spare pair of jumper cables to connect temporary grounds to identify and find problems.

[StephenVA]

Originally Posted by jfoj

The battery dampens and filters the alternator output.

One thing that most modern vehicles do is the DME/ECU can and will kill spark and fuel if the input Voltage gets too high to protect the DME/ECU and other modules in the car in the case of a high Voltage swing. Usually 17-19 Volts it the trip point for most vehicle. No idea the exact value for BMW and I am not interesting in finding out on any of my cars.

You can arc weld with 120-200 Amps and as mentioned it is not a wise test to disconnect the battery on a modern vehicle for testing. Without the battery as a static load and filter, the alternator can do some funny things. Even filtering out AC ripple that can high peak to peak Voltages.

A $20 Voltmeter or using the Hidden OBC Menu to access the Voltage and display it on the dashboard is all that is needed. Charging and starting systems are really easy to trouble shoot as long as the EWS does not get in the way.

Learn how to use a Multimeter/Voltmeter and learn how to perform Voltage Drop testing and you can correct the majority of problems that creep up. I also use a spare pair of jumper cables to connect temporary grounds to identify and find problems.