True or False

What was that?

What is that supposed to mean?
'saturated all the active sensitive electronic devices in the ignition/ECU and the car dies before those can come out of saturation.'

That is pure gobbly ****. I have read many different theories and heard different discriptions, but in all my years in school (through MSEE) and working as an EE (25 years) that is the first time I heard someone misuse so many words in one sentence!

How long do you believe it takes electronics to transition to and from saturation? Relative to an engine it is like comparing a snail to the speed of light. And putting a transistor in saturation is used for digital electronics not linear, and saturation occurs at the highest part of the load line not the lowest.

Disconnecting a cable is not the correct way to test a charging system, but I have never had one fail because the cable was removed. That does NOT make it right, only says I have been lucky.

Now if you remove and replace the cable while it is still turning over (and you have a bad charging system) you will probably cause a current surge that can be dangerous. Removing power and reconnecting with a good charging system can also be risky and is better to turn the car off then reconnect. But as I said disconnecting the negative with a failed charging system is similiar to the thousands of power downs the car performs.

PS A bad battery when the cable is disconnected is not in the circuit. Therefore, can not be the problem as he is discribing his 'test' method.



Post Edited (Oct 24, 12:32am)

Elaine - the battery is like a filter too. Theoretically your car will run off the alternator and practically it will run off the alternator too. Theoretically the battery is there to just start the car. But in the practical world problems blow holes in theory just like holes get blown in semiconductors.

The battery absorbs a lot of the transient spikes in the charging system. Those spikes on the power and ground planes of modern electronics are filtered by capacitors, which a battery really is, a big capacitor. But there comes a point when you drop a big rock in the lake and the water will flow over the dam (stone vs. meteor). Disconnecting a battery cable can create thousands of volts even when the car isn't running.

Walking across the carpet does the similar. Static electricity can cause damage that may go undetected to the human eye but affect performance in sensitive electronic devices. A really powerful microscope would show this, a car running lousy might show it also.

Him - It was a mouth full and was not meant to diminish your accomplishments as you and MANY others here have. I went back and reread, thinking I missed something that was stated. But I think you may have come to a few conclusions that were not mentioned in those earlier posts. And my post was not attacking any statements you made.

Semiconductors - transistors and diodes found in all active electronics including amplifiers which can saturate - undesired, (yes digital electronics makes use of saturation - desired, But no one was talking load lines here).

Yes electons travel pretty fast, and respnose times can be in nanoseconds. Just like the damage that can be done in any layer of the semiconductor from those speedy transients created when all your filtering capacitors are fully charged from that surge.

If you feel comfortable with your advise that's fine with me but at some point the car (maybe not yesterdays cars but definately tomorrows cars) will let you know you made a big mistake. Exceed a few thresholds and see if any error codes are generated.

why do I bother?

‘It was a mouth full and was not meant to diminish your accomplishments...And my post was not attacking any statements you made.’
What you say has NO impact on what I have done, I did not think or say you attacked me. I said what you wrote did not make sense.

‘Semiconductors - transistors and diodes found in all active electronics including amplifiers which can saturate’
Please explain how a diode enters saturation. My point was and is you are misusing terms. Saturation of a transistor in linear circuits will exit far faster than an engine stops. In this post you talk nano seconds but earlier stated
‘Either that or you've saturated all the active sensitive electronic devices in the ignition/ECU and the car dies before those can come out of saturation.’

So though a transistor switches in nano seconds the engine stops before it can come out of saturation? 800 RPM to 0 RPM in a nano seconds seems to be what you stated? That is silly and obvious non sense.

Explain all you want that is what you said, and what you said does not make sense. No one believes an engine goes from 800 RPM to a stop in less time than they can measure with a stop watch.



Post Edited (Oct 24, 8:31am)

and then

And you went on to say

‘- undesired, (yes digital electronics makes use of saturation - desired, But no one was talking load lines here).’
Saturation of a transistor in a linear circuit by definition is talking about operating points and load lines.

‘If you feel comfortable with your advise that's fine with me but at some point the car (maybe not yesterdays cars but definately tomorrows cars) will let you know you made a big mistake. Exceed a few thresholds and see if any error codes are generated.’

What are you trying to say? Read what I said! I stated
Disconnecting a cable is not the correct way to test a charging system...

I think what I said was CLEAR! But despite my saying ‘not the correct way’ you appear to have read it as an endorsement by me.



Post Edited (Oct 24, 8:46am)

and finally

‘Theoretically your car will run off the alternator and practically it will run off the alternator too....Theoretically the battery is there to just start the car. But in the practical world problems blow holes in theory just like holes get blown in semiconductors.’

At this point it would be easy to compare you to a politician, why are you talking in circles? A car will and does run off the battery. There are times when the charging system can not provide the power requirements of a car, and at those times uses the battery.

Elaine
As I stated it is safer to only connect and disconnect a battery when the engine is stopped. If the charging system is working correctly it still MIGHT cause a surge. Have I done it yes, can it cause damage yes. Why did I take the risk? Because I was too lazy to do it right, or stuck on the side of road. But the better way is to properly charge the battery BEFORE putting it in the car!

Despite doing that on even a 90's models I have not damaged a system. As I stated that can simply mean I have been lucky, it is NOT the recommended way to charge a battery.

Connecting and disconnecting a battery can and does cause power transients, they mainly affect the charging circuit but can pass through the charging system and effect other electronics.

Also a safety issue. Batteries give off gas which can and often does cause explosions! A battery exploding is a possibility and for that reason alone should cause everyone to never allow sparks around a battery.

And for puritans jumping a car can cause transients as large or larger than changing a battery in and out of a running engine.

PS De If a car can not run off just the alternator, wouldn't that mean it is using the battery? If the car is using power from the battery, then how does the battery stay charged?

PPS This will turn to flames soon so good luck all. Was interesting as usual.



Post Edited (Oct 24, 8:36am)

Ok, my disconnecting the battery and taking the battery out of a running car was actually a dangerous thing to do? Ok, the original question was:: If the neg. cable is removed the alternator is probably shot. Im trying to understand if that would apply to both Carbed and EFI vehicles.


Also, Jack brings up the Internally regulated vs. the Externally regulated(going to Z cars, now). I have a VR. The vehicle did not die when I removed the cable on the Z battery. I had brand new cables, and other electrical parts-coil, wires, connectors. The Charging System test I had done at Les Schwab indicated a bad alternator. However, my gut said No, so I went to Sears. They did a check...and were unable to determine what was wrong. They sent me to an auto electrical shop. After 45 minutes, the guy diagnosed Zel with a bad BATTERY...not a bad alternator. Ive had not one problem since installing my Interstate battery. Moral of that story is: Always get a second opinion! Also, when my electrical system was being checked, and rechecked, and rechecked by an electrician(certified) the handheld meters didnt show a bad battery. BUT, after about a month of testing...more or less, he one day said: Im beginning to think you have a bad battery. Now..... remember Chevy telling about Battery Molecules, and how cold can 'kill' Battery Molecules? I would think other things can 'kill' batteries, or keep batteries from charging properly... What Im saying to Buckley is.... dont rely on any ONE test.


Ok, Zquest... thanks for a such an in-depth answer..but now I have another question. If the battery 'absorbs' alot of "transient spikes" in the charging system, where do these 'spikes' go when the battery is disconnected, should the car be running?


Whew...... My experiences with the electrical system have been.... adventurous to say the least, Im just trying to pass on to Buckley things Ive gone through to determine what was electrically bad.... **** it..I hate it when I know what Im trying to say....but its not coming out right!

Elaine

Elaine
‘Ok, my disconnecting the battery and taking the battery out of a running car was actually a dangerous thing to do?'

Changing the battery while the engine is running can cause power surges, power surges can be harmful to electronics. Also connecting a battery in a running car can cause a spark, and a spark COULD cause the battery to explode. So yes dangerous is probably a good impression to leave.

‘If the neg. cable is removed the alternator is probably shot. Im trying to understand if that would apply to both Carbed and EFI vehicles.’
NOT the recommended way to check an alternator, but IF the negative battery cable is removed, and the car dies, the charging system is not functioning.

The problem could be bad grounds, the regulator, alternator etc. It doesn't matter whether it is carbureted or EFI. As mentioned older mechanical regulators with carburetors 'may' be less susceptible, but I think I prefer to error on the side of caution, and simply say do not remove the battery when engine is running.

The negative cable should be removed, because if it is dropped it will harmlessly short to the car (negative ground system). The engine should be turned off before reapplying the negative cable if the car died or kept running. And I would ensure the key and all devices are off as well before reconnecting.

Seems the rest of your post was self standing so no need for me to reply except to say not all people who test your car know what they are doing.



Post Edited (Oct 24, 1:00pm)

Ok Jack, thanks...but since we are on this Electrical thread....there are other questions.


The Old-Fashioned way of checking a charging system(removing neg) is just that:: Old Fashioned

I would think that because our cars are dinosaurs, we need to use the most up-to-date technology available to trace our electrical problems.

So, removing a cable and having a car stall is simply a 'warning' sign, no determination can be made to the cause, right?

If removing a battery, and hooking it up while the car is idling can cause a spark, which is dangerous, then we do not want to use this method regardless, right? Also, why would want to remove the negative cable at all if that can be dangerous? Am I summing you up correctly?


Right, not all mechanical shops actually 'know' what they are doing. Personally, I was impressed that Sears admitted that and sent my business elsewhere. So, where is the best place to start when seeking an electrical malfunction? The Battery?


Is not essential then, for every first and second Z owner to purchase a multimeter, voltmeter, ....something safer than the old fashioned way??


You know Jack, ANY test can be wrong... an intermittant problem can be pure **** to resolve. And ANY test is usually only as good as the person doing the testing.

Clarification

I didn’t mean to steal this thread. I suppose it covers information he wanted to know so I will try to expand.

‘The Old-Fashioned way of checking a charging system(removing neg) is just that:: Old Fashioned'

Well as you may remember in our youth there weren’t stores to take your generator, alternators, and batteries to for testing. So other methods were used. Now there are easier safer ways to perform these tests.

‘If removing a battery, and hooking it up while the car is idling can cause a spark, which is dangerous, then we do not want to use this method regardless, right? Also, why would want to remove the negative cable at all if that can be dangerous? Am I summing you up correctly?’

That is the point. Originally he asked if the ‘old’ method would work....Now we have progressed to the preferred method of testing. The preferred method is go to an auto store, and use the in circuit tester. Why because it is safer, and the guy at auto store performs the test while you stand safely away from where the battery could slash acid on you if the unthinkable happens.

Also if the car is inoperable they can test the alternator on their test stand, and battery in store as well.

To me the largest concern is someone will cause a spark on a battery that was charged hard and have an accident. A battery blowing up is DANGEROUS!

‘Right, not all mechanical shops actually 'know' what they are doing. Personally, I was impressed that Sears admitted that and sent my business elsewhere. So, where is the best place to start when seeking an electrical malfunction? The Battery?’

That depends on the symptoms. Personally I ALWAYS redo all grounds first. Most electrical problems are caused or worsened by bad grounds. Once I’m certain the system has all grounds connected properly then I will start to troubleshoot.

‘Is not essential then, for every first and second Z owner to purchase a multi meter, voltmeter, ....something safer than the old fashioned way??’
The multi meter is used for other trouble shooting. If a person can get to an auto parts store they will be able to test a battery, alternator, and if your grounds are good and other parts check then sell u a regulator if external. A multi meter is a valuable tool, but that is for another post I think.


‘You know Jack, ANY test can be wrong... an intermittent problem can be pure **** to resolve. And ANY test is usually only as good as the person doing the testing.’
Great close Elaine.