Welcome to City-Data.com Forum!
U.S. CitiesCity-Data Forum Index
Go Back   City-Data Forum > General Forums > Automotive
 [Register]
Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
View detailed profile (Advanced) or search
site with Google Custom Search

Search Forums  (Advanced)
Reply Start New Thread
 
Old 05-15-2011, 07:59 AM
 
Location: Victoria TX
42,618 posts, read 86,571,713 times
Reputation: 36637

Advertisements

Does your car consume more fuel when you are driving at night with the headlights on? If not, why not? Is that "free energy", which could be collected and stored as potential energy, during hours when lighting is not needed?

Perhaps a related thought. Would it make sense for a car to have three entirely separate electrical systems, each with it's own alternator.
#1 to keep a battery charged only to power the starter, which can never be run down by any other power usage, and is always fresh and fully charged, and can be easily removed and plugged into an AC outlet for quick recharge.
#2 only provides spark to the engine.
#3 drives all other accessories in the car, and can be easily upgraded for a car with intended heavy accessory use, like AC, driving lights or big audio amps.

Last edited by jtur88; 05-15-2011 at 08:15 AM..
Reply With Quote Quick reply to this message

 
Old 05-15-2011, 08:34 AM
 
Location: Northern MN
3,869 posts, read 15,119,482 times
Reputation: 3614
Yes,
When you turn on any accessory it puts a load/drag on the engine.
as do the lights.
The lights draw energy. This puts a load on the ALT. resulting in more fuel being used.
Reply With Quote Quick reply to this message
 
Old 05-15-2011, 08:35 AM
 
Location: U.S.A.
3,306 posts, read 12,150,127 times
Reputation: 2966
The law of conservation of energy.

Yes they do, but marginally... any electrical load requires energy and all of a car's energy comes from it's fuel. In a car the energy starts out as raw fuel (this is potential energy stored within the fuel molecules), it is then converted into mechanical energy through the internal combustion process it is then converted again through the alternator to electrical energy.

Through each conversion process energy is lost mainly in the form of heat from friction, so the conversions are not perfect. In the ideal world two 55W light bulbs would consume ~0.15 horsepower of engine output. With energy loss through conversion and depending on the efficiency of the engine that number is a bit higher. Even with no conversions from the root energy source (such as in an EV) they still consume.

Multiple electrical systems as you suggest would not help matters. To maximize efficiency it is best to consolidate your energy sources and eliminate as many conversions as possible. Also in this case it would also add mass to the entire system which is also not beneficial.
Reply With Quote Quick reply to this message
 
Old 05-15-2011, 08:40 AM
 
Location: Vermont
11,754 posts, read 14,561,248 times
Reputation: 18492
When considering this question, one way to think of it is to ask yourself where the energy to operate the lights would come from if not from burning gasoline.

In an internal combustion engine, everything the car does, except for the charge they gave your battery when you bought it, comes from burning gasoline.

Given the minuscule amount of energy things like the headlights use, it's almost a certainty that making your extra electric systems, putting them in the car, and carrying them around would use more energy than the electrical accessories consume.
Reply With Quote Quick reply to this message
 
Old 05-15-2011, 08:48 AM
 
Location: Victoria TX
42,618 posts, read 86,571,713 times
Reputation: 36637
I didn't mean to imply that the trifurcated electrical system would be more energy efficient. Of course, it would not be, if for no other reason than the triplication of costly hardware. The advantage would be the guarantee of an adequate power supply at all times for each of the three separate usage demands, without their parasitizing each other. This advantage would come at some cost, but a cost that would quickly be paid by anyone standing out on the side of a road in a below-zero windchill holding a set of jumper cables because he left his door ajar with the dome light on overnight.
Reply With Quote Quick reply to this message
 
Old 05-15-2011, 09:29 AM
 
Location: U.S.A.
3,306 posts, read 12,150,127 times
Reputation: 2966
Quote:
Originally Posted by jtur88 View Post
I didn't mean to imply that the trifurcated electrical system would be more energy efficient. Of course, it would not be, if for no other reason than the triplication of costly hardware. The advantage would be the guarantee of an adequate power supply at all times for each of the three separate usage demands, without their parasitizing each other. This advantage would come at some cost, but a cost that would quickly be paid by anyone standing out on the side of a road in a below-zero windchill holding a set of jumper cables because he left his door ajar with the dome light on overnight.
Capacities of typical alternators FAR exceed how much the vehicle can actually consume. I am still confused as to why you think multiple systems would work better if just one is already much more than enough.

Your example is also not entirely accurate, charging systems are for generation of energy, not storage. Having multiple alternators will not do someone any good if they leave a light on with the engine off. It's up to the battery to store the energy. Multiple batteries do make sense... and that has already been implemented, nothing new.
Reply With Quote Quick reply to this message
 
Old 05-15-2011, 11:13 AM
 
19,023 posts, read 25,864,073 times
Reputation: 7365
I agree with Lux and others. 1 Alternator is plenty, and would do no good if any and all batterys were discharged do to a oversight like leaving a light on.

The way around that is to set up a spare battery that can be switched manually to be 'The' battery to start and run a vehical. Once there was a 'A-B Switch' which was fully manual to run Battery A, Battery B or both at the same time.

Today there are other means where 2 batterys can charge anytime the Alt is running, but only one is used to start and run the engine, and the other is for acc items.

3 alts is just more weight to move around, and more than 2 batterys is too.

Also a good battery has a recover rate. You can drain a good battery past it's abilty to run a start motor, but given x time that battery if it's any good, will recover much of the charge and in a time be able to run the start motor and run the engine.

This depends on the state of charge, the abilty for the battery to hold a load and so on.

I have had this exact thing happen. My wife had a Saab, and I have a Volvo. One day we switched cars so I could do some maint on the Saab. She drove off 50 miles for a interview and later called me to say she left the head lights on Hi beam when she parked. That wasn't possible on the Saab.

I told her to turn off the lights and everything else, to make sure everything was OFF. I headed out in my truck with cables, but when I got there and she handed me the keys I just simply started the car.. That recovery occured in around 45 minutes.

That was before 2002 when I painted that car. I still have that same battery today, the one with blue over spray. I think I bought that battery around 1998.....
Reply With Quote Quick reply to this message
 
Old 05-15-2011, 11:29 AM
PDD
 
Location: The Sand Hills of NC
8,773 posts, read 18,294,212 times
Reputation: 12001
Quote:
Originally Posted by jtur88 View Post
Does your car consume more fuel when you are driving at night with the headlights on?
Yes of course it does but your car also uses more fuel when driving at 65-70- MPH then it does at 55.The experts say you can save 10-15% by driving at 55 MPH.

But who is going to do that? Certainly not me.
Reply With Quote Quick reply to this message
 
Old 05-15-2011, 02:44 PM
 
3,128 posts, read 6,496,339 times
Reputation: 1599
Which is why automakers are moving to LEDs, they have quite a few advantages.
1. They consume less energy
2. They are small so designers can be more creative.
3. They are brighter so safer
4. They last longer

Audi and Lexus offer LED headlights and the Germans and Lexus offer LED daytime running lights (and probably some others).
Reply With Quote Quick reply to this message
 
Old 05-15-2011, 02:53 PM
 
19,023 posts, read 25,864,073 times
Reputation: 7365
LED's are not the end all though since the viewer needs to be in line directly in many cases to see the light. The arrays are a tad costly still as well and many must use a resistor for the system to function. Normaly this is built into the array.

Nothing bugs me more than one led in a series going out, that nothing can be done to fix.
Reply With Quote Quick reply to this message
Please register to post and access all features of our very popular forum. It is free and quick. Over $68,000 in prizes has already been given out to active posters on our forum. Additional giveaways are planned.

Detailed information about all U.S. cities, counties, and zip codes on our site: City-data.com.


Reply
Please update this thread with any new information or opinions. This open thread is still read by thousands of people, so we encourage all additional points of view.

Quick Reply
Message:


Over $104,000 in prizes was already given out to active posters on our forum and additional giveaways are planned!

Go Back   City-Data Forum > General Forums > Automotive
Similar Threads

All times are GMT -6.

© 2005-2024, Advameg, Inc. · Please obey Forum Rules · Terms of Use and Privacy Policy · Bug Bounty

City-Data.com - Contact Us - Archive 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37 - Top