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Old 20th February 2009, 11:49   #166
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@bblost, from what the experts mentioned here, I guess the answer to your query is that, when you switch on extra lights, the alternator is working to provide power for that and thus its "battery charging" task goes on low priority, leading to draining the battery.
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Old 20th February 2009, 11:49   #167
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Originally Posted by bblost View Post
So why does running extra lights like 90/100 drain the battery.
If the battery is only sitting there and waiting for taking over when the engine is off.
To start the engine, ice or lights.
If engine rpm is low and the electrical load to be fed is high, the voltage from the alternator drops to a level equal to/below that of the battery. That is when the battery will also start getting drained. If the total load is well within the capacity of the alternator there will never be need for the battery to supply any part of it at normal speeds. In fact the battery will be getting charged too.
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Old 20th February 2009, 11:59   #168
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ok. so building on that.
Watts = amps * volts.

So if overall usage in watts is more than what the alternator is giving via amps then the battery steps in.

So the battery is loosing charge and not getting charged as well.
Hence the drain on its charge.

very basic look but I guess I get the picture or am I hopelessly lost?
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Old 20th February 2009, 12:04   #169
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Originally Posted by bblost View Post
...
very basic look but I guess I get the picture or am I hopelessly lost?
LOL, you're not at all lost! You've practically got it!

If large loads need to be run, an alternator of higher rating would need to be fitted. This, of course, will be increased load for the engine and a commensurate drop in FE is also to be expected!
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Old 20th February 2009, 12:15   #170
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Sir, why does a battery drain?
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Old 20th February 2009, 12:20   #171
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Originally Posted by headers View Post
Sir, why does a battery drain?

Headers. I don't understand why you would ask this.

But just to shoot off.
A battery is a bucket of energy. It keeps getting filled by the alternator.
It supplies energy to lights, starter, ice etc when the engine is off.
It also supplies energy when the alternator is unable to meet the load.

When the alternator is not already overworked its filling the battery's bucket.

But under highload conditions its not able to do that.
So the battery is giving out its energy and not getting refilled. It hence drains.

For some systems a cutout is used.
With a cutout the energy is taken from the battery directly. The alternator is charging the batter and the battery is feeding the lights. If its giving more than its getting then it drains.
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Old 20th February 2009, 12:43   #172
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Originally Posted by bblost View Post
For some systems a cutout is used.
With a cutout the energy is taken from the battery directly. The alternator is charging the batter and the battery is feeding the lights. If its giving more than its getting then it drains.
bblost, that was very nicely explained! Thanks.

Could you please elaborate a bit on the cut-out that you have mentioned?
I am not aware of this being used in cars. That all loads are fed from the battery and the battery is getting charged? How would this work out, simply in terms of voltages and current flows?
AFAIK, the cut-out is there to cut-off the charging to the battery when the battery has become fully charged.
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Old 20th February 2009, 12:47   #173
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Quote:
Originally Posted by anupmathur View Post
bblost, that was very nicely explained! Thanks.

Could you please elaborate a bit on the cut-out that you have mentioned?
I am not aware of this being used in cars. That all loads are fed from the battery and the battery is getting charged? How would this work out, simply in terms of voltages and current flows?
AFAIK, the cut-out is there to cut-off the charging to the battery when the battery has become fully charged.


I am not very strong on the cutout concept but what I understand is this.
A cutout allows you to take current directly from the battery and run the extra lights/ horns installed on a motorcycle.
My bike has a cutout installed for the Roots Vibrosonics.
No extra light fixtures on my bike.

I think the carb M800 has a cutout. Cos one biker I know had installed the M800 cutout on his bike. He had a lot of lights on his bike.
That is how I got to know that cars have cutouts as well.
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Old 20th February 2009, 13:16   #174
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bblost, as posted earlier, the alternator and the battery are wired up in parallel.
There is no way for loads to choose where they want to take power from. They will get supplied by whichever of the two has the higher voltage at that moment.
To charge a battery, a minimum voltage of 13.8 volts is required, so all alternators will produce anywhere from 14.2 to 14.6 volts. If the load is too much and the alternator is unable to meet the demand, the battery will start supplying as well, but it will certainly not be getting charged during this time. It will be getting DIScharged.

All cars have to have some means of cutting off battery-charging when the battery has attained full charge. This function is performed by a cut-out in most cars. Cutouts can be electro-mechanical relays with a small voltage sensing circuit or they can be fully solid state.

To recap, you cannot choose to supply ONE system from the battery and another from the alternator. All circuits will be supplied by one or the other or both. After all, they are in parallel!

If something has to be fed only from the battery, it will mean having to fix a switch to de-link the battery from the alternator. Also vice versa.

Hope this helps.
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Old 20th February 2009, 13:39   #175
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of course.

Quote:
Originally Posted by anupmathur View Post

To recap, you cannot choose to supply ONE system from the battery and another from the alternator. All circuits will be supplied by one or the other or both. After all, they are in parallel!

another point:
volts is just one part of the equation.
Can you provide an insight into the others as well.

thanks.
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Old 20th February 2009, 13:44   #176
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Quote:
Originally Posted by bblost View Post
A cutout allows you to take current directly from the battery and run the extra lights/ horns installed on a motorcycle.
My bike has a cutout installed for the Roots Vibrosonics.
No extra light fixtures on my bike.
Sir, you are RIGHT. A cutout is a relay used inbetween the electrical device and the battery to prevent the electrical device from drawing sudden load from the battery. One can also fix the electrical device without the cutout or relay but it is not advised as the battery fails faster!

Quote:
Originally Posted by anupmathur View Post
bblost, that was very nicely explained! Thanks.

Could you please elaborate a bit on the cut-out that you have mentioned?
I am not aware of this being used in cars. That all loads are fed from the battery and the battery is getting charged? How would this work out, simply in terms of voltages and current flows?
AFAIK, the cut-out is there to cut-off the charging to the battery when the battery has become fully charged.
Sir, you are getting it mixed up. All modern cars have a relays [or cutout in local parlance]. The relays are needed for smooth and steady supply of current from your battery to the electrical device..

But..please dont start again on your theories. I seem to have a different POV and hence the question, how does the battery drain.

Going by your logic, if the battery is only supplementing the alternator, then a battery should last much longer than the traditional 2 to 4 years!


Quote:
Originally Posted by bblost View Post

With a cutout the energy is taken from the battery directly. The alternator is charging the batter and the battery is feeding the lights. If its giving more than its getting then it drains.
A relay in used for HL, horns, ICE, fog lamps, additional horns etc.

Quote:
Originally Posted by anupmathur View Post
All cars have to have some means of cutting off battery-charging when the battery has attained full charge. This function is performed by a cut-out in most cars. Cutouts can be electro-mechanical relays with a small voltage sensing circuit or they can be fully solid state.
Sir, this cutout you are talking about is the regulator! it is in the alternator!

Cheers
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Old 20th February 2009, 13:50   #177
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Great Info...

I have a question here. I have noticed in some cars that the ICE setup(amps) is directly connected to the battery. In such a case -

1. What will be the source for supply? Battery right?
2. If its the battery then what would be the impact of this kind of a setup on the health of the battery?
3. If it is the battery and if it is not healthy for it then - is there a better way of powering the ICE?

Quote:
Originally Posted by anupmathur View Post
bblost, as posted earlier, the alternator and the battery are wired up in parallel.
There is no way for loads to choose where they want to take power from. They will get supplied by whichever of the two has the higher voltage at that moment.
To charge a battery, a minimum voltage of 13.8 volts is required, so all alternators will produce anywhere from 14.2 to 14.6 volts. If the load is too much and the alternator is unable to meet the demand, the battery will start supplying as well, but it will certainly not be getting charged during this time. It will be getting DIScharged.

All cars have to have some means of cutting off battery-charging when the battery has attained full charge. This function is performed by a cut-out in most cars. Cutouts can be electro-mechanical relays with a small voltage sensing circuit or they can be fully solid state.

To recap, you cannot choose to supply ONE system from the battery and another from the alternator. All circuits will be supplied by one or the other or both. After all, they are in parallel!

If something has to be fed only from the battery, it will mean having to fix a switch to de-link the battery from the alternator. Also vice versa.

Hope this helps.
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Old 20th February 2009, 14:34   #178
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Originally Posted by bblost View Post
So why does running extra lights like 90/100 drain the battery.If the battery is only sitting there and waiting for taking over when the engine is off.
To start the engine, ice or lights.
Please read post #107 on this thread for precise explanation.
A high peak current for a short time when the total load is high causes voltage drop below 14 Volts ( or whatever is alternator rating) once load is high enough so that alternator voltage drops below battery voltage of 12V the charge will flow from battery
Remember charge flows (current) from higer voltage to lower always.

If over a time period T , Battery drain time t1 is greater then charge time t2 then slowly the battery will start draining out.

if t1 > t2 on constant basis for all T then battery will die .


Cutouts / relays as you have mentioned in previous posts have different purpose to prevent the total current flow above certain maximum and prevent burn out.
Quote:
Originally Posted by KSM-Vtec View Post
Great Info...

I have a question here. I have noticed in some cars that the ICE setup(amps) is directly connected to the battery. In such a case -

1. What will be the source for supply? Battery right?
Battery and Alternator are connected in parallel , So even if physically ICE guy brought 2 thick wires and connected directly to battery terminal the physical location of connection does not change the parallel connection.

Now couple this with statement I provided at top of the post.
Remember charge flows (current) from higher potential to lower always.

ICE wires are connected to battery terminal because putting a cut in wiring elsewhere will void the warranty and if the original wire harness is thin it will burn due to high load.

Quote:
Originally Posted by KSM-Vtec View Post
2. If its the battery then what would be the impact of this kind of a setup on the health of the battery?
Amplifier does not constantly draw the peak current the amp rating is actually the peak rating, but peak current is drawn for small duration , So on an average if load does not cause for alternator voltage to drop below 12V constantly some portion of current will charge battery and it will work , If average amplifier load is more then power out put of alternator for sufficient long time battery will drain and if it does not charge plates will be destroyed and you will have dead battery.
[/quote]

Quote:
Originally Posted by KSM-Vtec View Post
3. If it is the battery and if it is not healthy for it then - is there a better way of powering the ICE?
Put another bigger capacity alternator or avoid putting such huge amplifiers and give some rest to ear drums and brain cells.

Last edited by amitk26 : 20th February 2009 at 14:39.
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Old 20th February 2009, 14:40   #179
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If you put more load on the system than alternator can handle your battery will be drained, else your battery will be charged.
For example.
Lets say I have an alternator in my car capable of giving 100A
If I have so much load on my system that it draws 110A, it will start depleting the battery. Eventually even with car started, battery will be drained completely.
So your average load on the system should be less than the generator, which in this case is the alternator.
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Old 20th February 2009, 14:59   #180
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Which cutout(this slang term actually means a relay or contactor) are all talking about here?
Alternator and battery are connected together through a heavy duty fuse. i have not seen one with "cutout". dose any of the new car have such heavy duty cutout?
Baleno dosen't have any charge control which cuts off battery when fully charged. there is a electrical load sensor for the ECU which outputs more fuel through the injectors when the load increase is sensed by it.battery is never cutoff from alternator.Regulator inside the alternator maintains the voltage. i don't know about latest cars.

ICE wire is taken directly from battery through thick wire to prevent voltage drop at the amplifier. have you seen how those demo cars play music? if it was only from its own alternator and battery it will be a few minutes or lesser of demo. they are powered externally.
The term cutout generally used in market is for headlights. its a thicker wire connected to battery through fuse, goes to a relay or two as per design and then powers the 90/100 and above headlights. The relay is controlled by stock headlight switch.
This is used to prevent the stock wiring of car from getting damaged as it is designed by law to carry only a 50/60w power. there is nothing like smooth flow or other theories. You can use 90/100 directly also but soon the weakest part of the stock car wiring will give way, first thing to go is the bulb holder.
Everything is connected to battery directly since it is technically easy to do than trying to connect directly to alternator. battery have bigger terminal to aid in giving the starting current but alternator has a much smaller one as its peak load capacity is much less than a battery.
For ICE, if you have a real powerful system which has a continuous draw of more than say 50% of alternator capacity, then the alternator has to be upgraded to a higher rating possible. This is limited by availability and space available. If you want to only momentarily deafen your friends then a second battery in parallel to one will do. if you car is monster ice then you will need a truck with a DC generator connected via trailer.
Batteries have a limited life because it is charged and discharged in a very irregular manner as per load on it.
Say, one car1 is started and stopped ten times a day and dose short trips.
car 2 is started few times a day and dose long trips, then battery in car2 will have longer life. hope it is clear.
batteries are not charged completely and then discharged completely in a temperature controlled environment. the temperature in engine bay is not good for battery. IF you can move the battery out of engine bay it will last longer, but where to keep it? Boot is a option but it needs to be ventilated forcefully.

Last edited by gigy : 20th February 2009 at 15:18.
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