Go Back   Team-BHP > Under the Hood > Technical Stuff


Reply
 
Thread Tools Search this Thread
Old 19th February 2009, 13:11   #136
Senior - BHPian
 
headers's Avatar
 
Join Date: May 2006
Location: Greater Chennai
Posts: 4,589
Thanked: 454 Times
Default

Quote:
Originally Posted by suman View Post
Vikram, give it up man. Anup will not try it for 20 minutes or a day because he knows it will run that long. So he doesn't want to waste his time.
Oh Yeah!!

Quote:
Originally Posted by sujaylahiri View Post
I believe that none of the modern cars can run without a battery or alternator disconnected.

The alternator only supplies so much voltage to charge the battery, however, your car's electricals might have different voltage and current requirements and hence won't run. Also I don't think there's a circuit which goes straight from the alternator to the main circuit of the car, unless you hard wire it physically.
+1 to that.

Quote:
Originally Posted by anupmathur View Post
Sujay, you are defeating the very purpose of this thread!
Not quite Sir, he is educating us the right way, just that it does not coincide with your views.

Maybe the thread title should be changed to "Will removing the battery and running your petrol car screw it up or not?" What say friend.


Quote:
Originally Posted by anupmathur View Post
That it will run is of no consequence to me other than having the confidence that, if needed, it could be done. Academic!
My reason for not wanting to try any of this is simpler: As I said before, I do not intend to plan/make any trip without all stock components of the car being in good order!
Sir, I guess your academic interest needs to be verified! Many of us at TBHP are eager to witness the results. I for one, dont think its possible cos I know its not!

If you are so sure about your concepts, then please prove it and I'll stand corrected. Please note that e-learning is not as great as practical hands on experience!


Quote:
Originally Posted by anupmathur View Post
Hahaha, headers, is that supposed to be a joke?
Please bear in mind that these might just get taken seriously by some people!
Thanks for laughing at my joke, am glad it made you laugh. Test your statements and we all can join you in the laughter!

Quote:
Originally Posted by anupmathur View Post
The purpose of the thread was rather different!
Those who wish to gain some knowledge from it are welcome to do so,
Whats the use of incorrect knowledge if one cant use it at times of need

Quote:
Originally Posted by suman View Post
I would not continue this experiment long term, not sure if there's anything else that's getting screwed up in the process
Come on Suman, you cant give up after reading this thread. There's only 1 person who says the car WILL NOT run for more than 10 or 20 kms without bursting something, so why dont you try? Please..

Last edited by Rehaan : 19th February 2009 at 20:57. Reason: Rephrasing. Please be polite.
headers is offline   Reply With Quote
Old 19th February 2009, 13:39   #137
Distinguished - BHPian
 
supremeBaleno's Avatar
 
Join Date: Dec 2005
Location: Weekdays@Chennai, Weekends@Kerala
Posts: 5,164
Thanked: 1,638 Times
Default

Quote:
Originally Posted by headers
There's only 1 nut who says the car WILL NOT run for more than 10 or 20 kms without bursting something
Vikram, what are you saying will burst in the car if run without battery connected for 10-20kms ?
supremeBaleno is offline   Reply With Quote
Old 19th February 2009, 13:51   #138
BHPian
 
Samir Taheer's Avatar
 
Join Date: Sep 2008
Location: London & Pune
Posts: 392
Thanked: 60 Times
Default

I think what headers is trying to say is - That the battery works as sort of a capacitor, and if you run the car without it, the surge/fluctuation in voltage may affect your ECU or other electronic components.... Yes?

I've said earlier in this thread - I spoke to a few engineers that work at Delphi and they all seem to think that the alternator is the primary source of charge, the battery is only there for starts to and ease the load of the alternator if required. They thought the engine should run without the battery, but like alot of people here have said there may be consequences. They also sid the only reason the engine would not run, is if the alternator is weak or with modern cars there is a sensor to gauge if a battery is there or not.

Guys i am not saying anyones right/wrong or anything - just stating what i think a reliable source has said.
Samir Taheer is offline   Reply With Quote
Old 19th February 2009, 14:43   #139
Senior - BHPian
 
headers's Avatar
 
Join Date: May 2006
Location: Greater Chennai
Posts: 4,589
Thanked: 454 Times
Default

Quote:
Originally Posted by supremeBaleno View Post
Vikram, what are you saying will burst in the car if run without battery connected for 10-20kms ?
Biju, try it man, you got a BALENO afterall...

On a serious note, the alternator's regulator / rectifier will go bust if you run your car with the battery disconnected!


Quote:
Originally Posted by Samir Taheer View Post
I think what headers is trying to say is - That the battery works as sort of a capacitor, and if you run the car without it, the surge/fluctuation in voltage may affect your ECU or other electronic components.... Yes?
More or less sir!

Maybe a reservoir of charge.
headers is offline   Reply With Quote
Old 19th February 2009, 14:58   #140
Senior - BHPian
 
esteem_lover's Avatar
 
Join Date: Jul 2006
Location: Madras/Py
Posts: 7,554
Thanked: 445 Times
Default

So, if I have 3 cars and I am an el cheapo, I can have just one battery fixed in my garage & jump start each of the cars & just keep driving. The alternator would do just fine.
esteem_lover is offline   Reply With Quote
Old 19th February 2009, 15:07   #141
Distinguished - BHPian
 
supremeBaleno's Avatar
 
Join Date: Dec 2005
Location: Weekdays@Chennai, Weekends@Kerala
Posts: 5,164
Thanked: 1,638 Times
Default

Normally just the fact that you own 3 cars would suggest that you are not el cheapo, John.
#Ofcourse, standard exceptions apply.

BTW, your logic won't work because you would not just be keeping on driving. Once you stop somewhere, you would need to start the car again for which you need a battery. But your common battery is far away in your garage.

Vikram, I am not bold enough to try this on the Baleno. But 'might' just try this on our non-ECU M800.

Last edited by supremeBaleno : 19th February 2009 at 15:11.
supremeBaleno is offline   Reply With Quote
Old 19th February 2009, 15:29   #142
Senior - BHPian
 
esteem_lover's Avatar
 
Join Date: Jul 2006
Location: Madras/Py
Posts: 7,554
Thanked: 445 Times
Default

Quote:
Originally Posted by supremeBaleno View Post
BTW, your logic won't work because you would not just be keeping on driving. Once you stop somewhere, you would need to start the car again for which you need a battery. But your common battery is far away in your garage.
There is always enough and more manpower available in our country. Damn, I can even switch off in the signals, there are enough and more beggars/eunuchs/vendors who will give my car a nudge for a very very small consideration.
esteem_lover is offline   Reply With Quote
Old 19th February 2009, 15:35   #143
Senior - BHPian
 
KSM-Vtec's Avatar
 
Join Date: Jun 2008
Location: MH-02-India-Bombay-Bandra
Posts: 1,563
Thanked: 437 Times
Default

That reminds me of an incident that happened last week. I left my car with the headlights on and got back only after a few hrs. The battery was totally drained and was lucky enough to get help from the people around before i could ask them...talk about India and you will find people who are willing o help...

Quote:
Originally Posted by esteem_lover View Post
There is always enough and more manpower available in our country. Damn, I can even switch off in the signals, there are enough and more beggars/eunuchs/vendors who will give my car a nudge for a very very small consideration.
KSM-Vtec is offline   Reply With Quote
Old 19th February 2009, 15:45   #144
Senior - BHPian
 
esteem_lover's Avatar
 
Join Date: Jul 2006
Location: Madras/Py
Posts: 7,554
Thanked: 445 Times
Default

Quote:
Originally Posted by supremeBaleno View Post
Normally just the fact that you own 3 cars would suggest that you are not el cheapo,

Ok, 10 el cheapos living in an apartment complex.
esteem_lover is offline   Reply With Quote
Old 19th February 2009, 16:32   #145
Senior - BHPian
 
Join Date: Jul 2008
Location: Bangalore
Posts: 2,035
Thanked: 384 Times
Default

Quote:
Originally Posted by headers View Post
Biju, try it man, you got a BALENO afterall...

On a serious note, the alternator's regulator / rectifier will go bust if you run your car with the battery disconnected!

Can you please enlighten us why would a rectifier go bust if the battery is not connected ? I could have agreed to some extent if you would have said that ECU or any other gadget will go bust due to spikes but that is also unlikely scenario if you are interested in knowing why please read on
else I rest my case here without engaging in any further discussion.

I hope you do know what is a bridge rectifier and how it functions with 4 diodes. Any semi-conductor diode can be destroyed in common language if and only if

(a) The reverse current is more then the break down current.
(b) Or the total forward current is more then it's rating ( burn out will happen)

Either of the two conditions may happen irrespective of battery being in place or not because reverse currents are encountered across diodes due to alternating cycles and not some thing which can not be prevented by battery.

The forward current being more then rating means the whole system is overloaded which is again not some thing which a battery can prevent.


The current spikes in the circuit are results of irregular waveforms ( square waves) and diodes in rectifier do not go bust as long as the current is below the rated capacity.

The sole job of rectifier is to convert alternating current to DC , The output of alternator is not a pure sine wave and there are many harmonics . Ractifier just converts these to DC and makes no attempt to give constant DC that would be a job of regulated power supply usually( with a disclaimer for possible high end cars ) there is no centralized power regulator IC else you would never notice voltage change with engine revving up. Even if there is a regulator IC placed it would contain a capacitor of it's own rather then depending on a variable capacitance device like battery for damping.

For a moment Lets assume that there is a regulated power supply in Car and regulator circuit designers are smart / stupid enough to rely on battery for capacitance , Removal of capacitance wont harm regulator itself but gizmos using the unregulated DC current would malfunction as spikes due to rectification or irregular waves wont be damped.

Even if you believe that battery acts as a capacitor it can not protect diodes of a ractifier , No capacitor of whatever capacitance at the output terminal of a rectifier can protect ractifier from reverse currents. Purpose of capacitor is to provide damping and protect circuits down the line from surge.


Folks this thread is becoming more and more ridicules by the day ,
See some samples

(a) Starting point was an electrical fan would load engine less then mechanical fan of same power consumption rating

(b) then some one said that alternators charge battery for free ( implying no load on engine )

(c) then there was another gem from another gentleman that alternator is not the sole primary source of charge in a car ( what else is there ? a nuclear reactor )

(d) fully knowing that alternator Voltage is approx 14 V and battery is 12 V and they are connected in parallel still people go on arguing that current will be drawn from battery , I hope people do remember that Michael Farady proved couple of centuries ago that charge flows from higher potential to lower.

(e) Battery is a must because it's capacitance is required to protect ractifier.

Last edited by amitk26 : 19th February 2009 at 16:37.
amitk26 is offline   Reply With Quote
Old 19th February 2009, 17:25   #146
Senior - BHPian
 
gigy's Avatar
 
Join Date: Jul 2006
Location: mumbai
Posts: 1,321
Thanked: 41 Times
Default

anupmathur, whats the purpose of this thread?
your thread title is a very generalized question. please mention your car for specific answer. there is old amby on road and also the latest BMW. so the thread has to be car specific.
sujaylahiri, battery dosen't serve as a conduit for the current from the alternator. battery is always connected in parallel.
I have run my car for more than 7kms without battery to check the alternator and it didnt shutdown. AC was not used. May be old baleno electronics are less sensitive.
amitk26, you are very correct.
gigy is offline   Reply With Quote
Old 19th February 2009, 17:36   #147
Senior - BHPian
 
esteem_lover's Avatar
 
Join Date: Jul 2006
Location: Madras/Py
Posts: 7,554
Thanked: 445 Times
Default

Quote:
Originally Posted by gigy View Post
anupmathur, whats the purpose of this thread?
your thread title is a very generalized question. please mention your car for specific answer. .
anup did not start this thread. This was an offshoot created from another thread by a moderator.
esteem_lover is offline   Reply With Quote
Old 19th February 2009, 17:40   #148
Senior - BHPian
 
Join Date: Sep 2007
Location: New Delhi
Posts: 3,083
Thanked: 252 Times
Default

Very well explained, Amit!

I would like to add two things in the context of what you have said.

Quote:
Originally Posted by amitk26 View Post
(a) The reverse current is more then the break down current.
It is not really the current, it is the voltage.
Any diode can withstand only up to a designed reverse voltage. Once this breakdown voltage is exceeded, the diode breaks down and reverse current flows through it, frying it almost instantly. Very small reverse currents can fry a diode. This can result in either a shorted diode or an open circuit.

In the correct conductance direction, the diode will get fried only if current much larger than its rating is allowed to flow, as you have already mentioned.



The other thing is about the battery being needed as a capacitance device for a rectifier/regulator to work successfully. This is not correct.
The rectifier puts out three phase, full wave rectified AC which is close enough to DC for basic electricals. Hence, in cars, a bridge rectifier is not used; just three phase full wave rectification.

Electronic components that require rectified and filtered (pure) DC, like ECUs and other 'control boxes', will have their own filters and regulation built in. The presence of a battery is not of consequence to them, nor is it essential. They will work well enough with the output of an alternator.

Kindly let me know if the above is in order.



Quote:
Originally Posted by gigy View Post
anupmathur, whats the purpose of this thread?
LOL, gigy, I did not actually craete this thread! This has been separated from another thread where this discussion started as an off topic!
My intention was simply to clarify that once a car has been started, the role of the battery is pretty much over as it is the alternator that supplies all the requirements of the car!

I am not the least interested in finding out WHICH cars will run for how long etc..etc...!

Last edited by anupmathur : 19th February 2009 at 17:41.
anupmathur is offline   Reply With Quote
Old 19th February 2009, 17:52   #149
Senior - BHPian
 
Join Date: Jul 2008
Location: Bangalore
Posts: 2,035
Thanked: 384 Times
Default

Quote:
Originally Posted by anupmathur View Post
Very well explained, Amit!

I would like to add two things in the context of what you have said.



It is not really the current, it is the voltage.
Any diode can withstand only up to a designed reverse voltage. Once this breakdown voltage is exceeded, the diode breaks down and reverse current flows through it, frying it almost instantly. Very small reverse currents can fry a diode. This can result in either a shorted diode or an open circuit.
Of course yes Voltage exceeding would result in breakdown current. It was long post so mistake.


Quote:
Originally Posted by anupmathur View Post
The other thing is about the battery being needed as a capacitance device for a rectifier/regulator to work successfully. This is not correct.
The rectifier puts out three phase, full wave rectified AC which is close enough to DC for basic electricals. Hence, in cars, a bridge rectifier is not used; just three phase full wave rectification.
I put the assumption of battery as capacitor to prove the assumption wrong I did not mean it is indeed the case.

Quote:
Originally Posted by anupmathur View Post
Electronic components that require rectified and filtered (pure) DC, like ECUs and other 'control boxes', will have their own filters and regulation built in. The presence of a battery is not of consequence to them, nor is it essential. They will work well enough with the output of an alternator.

Kindly let me know if the above is in order.
Yes that should be the case I see no reason why they cant put a regulated power supply stage costing peanuts in retail in to an ECU costing 30K to 1 Lakh. Probably some hypothetical luxury car would have a centralized regulator to supply pure regulated 12V DC to everything.
amitk26 is offline   Reply With Quote
Old 19th February 2009, 17:53   #150
Senior - BHPian
 
gigy's Avatar
 
Join Date: Jul 2006
Location: mumbai
Posts: 1,321
Thanked: 41 Times
Default

i will post the picture of actual circuit diagram of my baleno. hope it will help in clarifying many of our doubts.
Attached Thumbnails
Alternator Dependency: Will a vehicle run with the battery disconnected?-generator-description.jpg  

Alternator Dependency: Will a vehicle run with the battery disconnected?-power-supply-diagram.jpg  

Attached Images
 
gigy is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Battery / Alternator / Voltage Regulator problem? babe_on_wheels Technical Stuff 108 20th October 2017 10:23
Battery Not charging light on - Alternator giving 14+ !! What is it ? karizma_devil Technical Stuff 90 30th August 2012 21:00
Battery / Alternator problem in Ambassador Diesel adrian Technical Stuff 5 11th December 2009 14:25
M800 - Vaporizer tube disconnected eternalck Technical Stuff 5 14th July 2009 13:39
MP3 Player gets Disconnected navdeep Technical Stuff 11 18th January 2007 16:56


All times are GMT +5.5. The time now is 12:44.

Copyright 2000 - 2017, Team-BHP.com
Proudly powered by E2E Networks