Question: Need advice on Electrical

[geekinavette]

The battery does not "power" anything once the engine is running...the alternator does that. If the battery were providing power it would eventually run down!

 

[John Robinson]

John, some folks forget that a battery does not only start the vehicle, but is also the sole source of energy for the ignition system. Congratulations on your repair!
I think what LT4Man is saying (Correct me if I am wrong Greg) is that if the battery is weak and not holding a full charge then the Alternator which should be providing voltage to the running of the car is being diverted to keep the battery charged and therefore the available voltage for engine is reduced. In my case until I put the new battery in I was charging at 14.9 to 15 volts trying to power everthing. Now my voltage runs 14 to 14.3 because the battery is holding its charge.

 

[geekinavette]

John...I'm not trying to "argue" with Greg, altho it HAS been a while since I gave him any crap!
(I know, Greg...I'm slackin! :L)

This is just an area that can get quite confusing and happens to be my area of expertise.

It HAS been quite a while since the last "tech article"...maybe this would be an excellent subject for one!

Stay tuned...

 

[Patrick]

It HAS been quite a while since the last "tech article"...maybe this would be an excellent subject for one!

Stay tuned...

:ugh
Oh, c'mon, Bill, not during the holiday season. Wait until January, when no one is going to mind reading something that puts them to sleep.


-Patrick

 

[LT4man]

The battery does not "power" anything once the engine is running...the alternator does that. If the battery were providing power it would eventually run down!

Hi, Bill, Merry Christmas!

Now that I have the "pleasantries" out of the way................

I was already hibernating, but this was too good to pass up................

Bill, show me a motor vehicle (driven on the streets of our country, not a 1/4 mile dragster! ) that will run without a properly charged and good battery.

Like when I drove my CE LT4 Vette to Colorado Springs a couple of years ago...........I think I had a good battery in my Vette!

I'm waiting!!!

WHILE YOU ARE FORMULATING YOUR ANSWER, PLEASE SAVE THE

 

[geekinavette]

Patrick...hey no better time than the present!

Greg...have you never disconnected a battery while an engine is running? Try it! As long as the alternator is working properly nothing will happen...it'll keep running just dandy. Granted there may be a slight voltage fluctuation as the load of the battery on the alternator is disconnected so something with lots of sensitive electronics is probably not a good idea...but the fact remains that current only flows INTO the battery while the engine is running, not out of it.

 

[92BlackVette]

I got a ticket in my 76 Vette when I was 16, for going to slow of all things when he pulled behind me; the cop thought I was DUI. I told him I just started driving a week ago and I was intimated by police. The ticket was for driving with expired inspection. A little foreshadowing I guess, I average about 2 a year since then.

 

[m14mike]

Those guys just got lucky...most cops are doooshbags. The last three times I tried the honest polite route all I got was "thanks for being so polite" as the a-holes handed me my tickets!

 

[John Robinson]

Those guys just got lucky...most cops are doooshbags. The last three times I tried the honest polite route all I got was "thanks for being so polite" as the a-holes handed me my tickets!

Age has it's advantages

 

[LT4man]

Patrick...hey no better time than the present!

Greg...have you never disconnected a battery while an engine is running? Try it! As long as the alternator is working properly nothing will happen...it'll keep running just dandy. Granted there may be a slight voltage fluctuation as the load of the battery on the alternator is disconnected so something with lots of sensitive electronics is probably not a good idea...but the fact remains that current only flows INTO the battery while the engine is running, not out of it.

Bill, I am so disappointed. Of course, I have disconnected batteries while engines have been running. I have not made a practice of this.

I was so looking forward to a very in-depth explanation. otfl

I beg to differ with you about the direction of current flow. Current flows out of the battery and back into the battery. Whilst the engine is running.

The battery energizes the alternator. And keeps all the electricals being electrical. The alternator continuously replenishes the charge in the battery. The process is cyclical. And everybody is happy!

SAVE THE

 

[geekinavette]

Bill, I am so disappointed. Of course, I have disconnected batteries while engines have been running. I have not made a practice of this.

Ahah so we've established that an engine CAN run without a battery! Granted you can't START it...but it will RUN!

I was so looking forward to a very in-depth explanation. otfl

I know I know! It will come...I am just quite time limited right now...but I'm working on it!

I beg to differ with you about the direction of current flow. Current flows out of the battery and back into the battery. Whilst the engine is running.

Sorry to say my friend...this is simply not true (under normal operating conditions). More detail to come...

The battery energizes the alternator. And keeps all the electricals being electrical. The alternator continuously replenishes the charge in the battery. The process is cyclical. And everybody is happy!

Partly correct...again more detail to come (when I have time to finish it)...

 

[LT4man]

Ahah so we've established that an engine CAN run without a battery! Granted you can't START it...but it will RUN!

I have spent most of my adult life causing engines to run well. I highly advise against running an engine without a battery. Just because you can do that does NOT mean that should be done! otfl

And I have not even addressed where the ignition coil receives its initial voltage. If you can run an ignition without that voltage, you can make you and me very rich!

And this is all I will have to say about this subject. I would recommend anyone disagreeing with my opinions to work on engines for almost forty (40) years and then get back to me!

AND WHILE YOU ARE AT IT, PLEASE SAVE THE !

 

[82ColEd]

Uh Oh, didnt mean to stir the pot

:L

My confusion is just that i watch race cars without battery (i assume here, weight issue and all) and a guy with a starter in his hand to start them, so the battery cant have too much to do with "running" the engine, right ?

I for one, am patiently hnoes awaiting Bill's document.

And i'll tell

to be nice to you two.



-Stefan

 

[geekinavette]

Ohh I am not done with it! There will be a writeup (eventually)...not based on experience or opinions, but laws of physics!

 

[geekinavette]

Uh Oh, didnt mean to stir the pot

:L

My confusion is just that i watch race cars without battery (i assume here, weight issue and all) and a guy with a starter in his hand to start them, so the battery cant have too much to do with "running" the engine, right ?

I for one, am patiently hnoes awaiting Bill's document.

And i'll tell

to be nice to you two.



-Stefan

heheh Stefan....naw man nothing wrong with a good technical discussion! Not the first time Greg and I have had a lil disagreement, and won't be the last i'm sure! As long as we all learn somethin' then the goal is achieved!

'sides poor Patrick has been going through "tech article" withdrawls for months now...it's about time!

 

[LT4man]

My confusion is just that i watch race cars without battery (i assume here, weight issue and all) and a guy with a starter in his hand to start them, so the battery cant have too much to do with "running" the engine, right ? -Stefan

Stehan,

I made an exclusion of 1/4 mile dragsters & funny cars earlier.

The reason those vehicles do not use a battery to ignite (pun intended!:L) their ignition is because those engines use magnetos.

For your every day motor vehicle (except diesel engines which derive their ignition from the heat of their very high [22:1 for example] compression) batteries are their only original source of energy.

I am trying to keep this exchange simple so that even folks without engineering degrees can follow and understand these principles.

Going back to sleep, now! Everyone have a very Holy & Merry Christmas!

I AM GOING TO SAVE THE GOSH DARN !

 

[TODD L GRIFFITH]

That is also the oldest test in the book to find out if you have a bad alternator or not. Start the car and remove both of the battery cables. If the car keeps running, the alternator is good. If it dies, it's a bad alternator.

 

[G Winter]

OK I can't let this go with out my two cents worth.
A car WILL run just fine without a battery once it is started and the alt. is working the way it should. If it depended on the battery then would the battery not eventually lose all it's charge? The exception to this is accessories. If you have some of those running that take intermittent surges of current then the alt. may not be able to supply enough for both the accessory and the ignition. In this case current has to come from the battery to help.

Glenn

 

[LT4man]

OK I can't let this go with out my two cents worth.
A car WILL run just fine without a battery once it is started and the alt. is working the way it should. If it depended on the battery then would the battery not eventually lose all it's charge? The exception to this is accessories. If you have some of those running that take intermittent surges of current then the alt. may not be able to supply enough for both the accessory and the ignition. In this case current has to come from the battery to help.

Glenn

Glenn, see post #22 above.

I will reiterate what I said earlier. A bad battery will cause a vehicle's ignition to be poor and the engine will NOT run as well.

I did not learn this from a book. Although, I have learned many things from books, both mechanical and non-mechanical.

Today's electronic ignition systems and electronic fuel injection systems have caused batteries and their state of charge to be much more critical to the running of our engines.

Talk to c4c5 specialist regarding the C5 and the C6 and battery performance. Or to any C5 and/or C6 owner!

Now, let me go back to sleep. I have lots of things to do in the Spring after I wake up. Lots of Vette things on my to-do list!

WHILE I AM SLEEPING, WOULD SOMEONE PLEASE SAVE THE ?

 

[geekinavette]

OK I can't let this go with out my two cents worth.
A car WILL run just fine without a battery once it is started and the alt. is working the way it should. If it depended on the battery then would the battery not eventually lose all it's charge?

Yep it sure would.

The exception to this is accessories. If you have some of those running that take intermittent surges of current then the alt. may not be able to supply enough for both the accessory and the ignition. In this case current has to come from the battery to help.

Glenn

The battery is an electrical "load" on the alternator...as it charges up its internal resistance increases, taking less and less current away from the alternator. When a battery goes "bad" and takes more and more current to keep it charged up, that current of course has to come from the alternator. If it gets to a point where it needs more than the alternator can provide, the alternator's output voltage can fluctuate, even drop, to the point where electrical system performance starts to suffer...as Greg points out. Ignition voltage suffers (and as a result weaker spark), injector flow rates can be affected...so on and so on.

Likewise as you mention when accessories are added that exceed the alternator's ability to provide current, again the output voltage drops or fluctuates, there isn't enough current to keep the battery charged and electrical systems suffer in performance. And yes when/if the alternator voltage drops to a point below that of the battery, then current will flow from the battery. Basic Ohm's Law!

Steady voltage from the alternator is VERY critical...absolutely agree with that! We just can't have alternator/battery voltages jumping around all over the place with these sensitive electronic systems.

I'm trying to work out a write up that's easy to understand...just saying something "is what it is" without explaining why has never been good enough for me!