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Old 7th April 2009, 00:35   #1
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Default Battery consumption and installing LCDs

Guys, I am quite new to this forum and this is my first post.

I am doing a research project on the car battery and consumption of the various units found in a car.

I want to understand some basics about the car batteries of a car (lets take a Maruti Esteem as an example)

1. What is the capacity of the battery (I believe this is measured in AmpHours?)?
2. What is the consumption of the various units inside a car:
a. Air conditioner
b. Cigarette charger
c. Headlights
d. Interior lights
e. Wipers
f. Radio
3. What would be the total power used by an LCD screen installed on the rooftop or the headrest, which draws 12V power from the battery at ~7 W?
4. Would this require a higher capacity battery to be installed?
5. Is there a chance that the LCD screen can drain the battery if a higher capacity battery is not installed?
6. Can an additional accessory like this reduce the lifetime of the battery? Is there any scientific way to test this?

Does anyone know anyone or anywhere, where I could attempt installing such a screen and testing something like this out, or to whom I could goto to get such information? Any relevant references/contacts would be appreciated.

Thanks a lot.

Regards,
Varun
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Old 7th April 2009, 13:23   #2
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Hi Varun,

Welcome.

I'm sure you will get all your answers here. Why dont you start off by reading some of the existing discussions on very similar topics

(read a few pages past this point)
http://www.team-bhp.com/forum/4x4-of...ar-jeep-8.html

http://www.team-bhp.com/forum/techni...r-battery.html (Car battery!)

http://www.team-bhp.com/forum/techni...att-lamps.html (Why relay for high watt lamps)

+++ search for more

cya
R
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Old 7th April 2009, 13:28   #3
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>> Is there a chance that the LCD screen can drain the battery
>> if a higher capacity battery is not installed?

As long as you operate the electrics when the engine is running, no problems at all, since the battery is not discharging, but charging. A power amp or headlamp or any such 'heavy' consumers of power can drain the car battery over time if engine is not running. As simple as that.

I dont' think you should change your battery to a higher capacity one just because you installed an LCD display. IMO, it doesn't consume much power. If a laptop display can be kept alive for 3 huors by its smaller Li-Ion battery, why not the car battery?

Last edited by clevermax : 7th April 2009 at 13:33.
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Old 7th April 2009, 13:43   #4
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Thanks for the replies guys.

Rehaan I looked at the articles, but didn't really find the information I was looking for.

Basically, what I am looking for is a breakdown of use. For example,

A Maruti Esteem usually has a 35 AH battery. Assuming the car is not on, the AC would take x Amps, Lights would take y amps, Radio will take z amps, and in comparison the LCD will take q amps.

Also, if a normal battery lasts for 3 years (assumption), how long would it last with this additional accessory.

Also, does anyone know if there is someone in South Bombay who can help me mod my car, and can give me exact technical details???

Thanks
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Old 7th April 2009, 14:23   #5
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Quote:
Originally Posted by varunj View Post

A Maruti Esteem usually has a 35 AH battery. Assuming the car is not on, the AC would take x Amps, Lights would take y amps, Radio will take z amps, and in comparison the LCD will take q amps.

Also, if a normal battery lasts for 3 years (assumption), how long would it last with this additional accessory.
I have a PowerAmp in my car and I play it often when the engine is off. It's been 3 years and my battery never complained. Just do not let the local service guys pour water or acid or anything into a maintenece free battery, in the name of preventive maintenence.

And, AC won't work when the engine is off... its onl the blower (fan). I hope that's what you meant. (Unless you have some non OEM ac system that operates directly from battery)
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Old 7th April 2009, 15:30   #6
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Answers in line

Quote:
Originally Posted by varunj View Post
Guys, I am quite new to this forum and this is my first post.

I am doing a research project on the car battery and consumption of the various units found in a car.

I want to understand some basics about the car batteries of a car (lets take a Maruti Esteem as an example)

1. What is the capacity of the battery (I believe this is measured in AmpHours?)? 35AH
2. What is the consumption of the various units inside a car:
a. Air conditioner Blower would consume say 4A
b. Cigarette charger - negligible
c. Headlights - 60W*2=120/12=10A
d. Interior lights - 2A max
e. Wipers - Not Sure
f. Radio - 8A max.
3. What would be the total power used by an LCD screen installed on the rooftop or the headrest, which draws 12V power from the battery at ~7 W? Not Sure
4. Would this require a higher capacity battery to be installed?No
5. Is there a chance that the LCD screen can drain the battery if a higher capacity battery is not installed? Not really
6. Can an additional accessory like this reduce the lifetime of the battery? Is there any scientific way to test this?

Does anyone know anyone or anywhere, where I could attempt installing such a screen and testing something like this out, or to whom I could goto to get such information? Any relevant references/contacts would be appreciated.

Thanks a lot.

Regards,
Varun
Please look into the Esteem's Manual and go to the page which gives details of the Fuse Box.

Different fuses are linked to different units - the power consumption in amps could be closely related to the fuse rating - if the fuse says 10A,80% of that would be the max current drawn

My Versa's battery is still going strong after five and a half years - that too with power guzzlers(90/100 halogens,Power amplifier) on tap . The battery life has a lot to do with how good the wiring is(old is not good),the roads(bad isn't good),the alternator,etc.

Last edited by vigsom : 7th April 2009 at 15:33. Reason: incomplete post
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Old 7th April 2009, 18:32   #7
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7W of additional load is pittance. Probably the cabin-light would consume equivalent amount of power.

So, fear not, add the screen and enjoy the movies on the move.
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Old 7th April 2009, 19:56   #8
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Quote:
Originally Posted by clevermax View Post
I have a PowerAmp in my car and I play it often when the engine is off. It's been 3 years and my battery never complained. Just do not let the local service guys pour water or acid or anything into a maintenece free battery, in the name of preventive maintenence.

And, AC won't work when the engine is off... its onl the blower (fan). I hope that's what you meant. (Unless you have some non OEM ac system that operates directly from battery)
If the electrolyte level does go down , you have to fill it up , even if it is maintenance free . Maintenance free in reality for batteries = low maintenance .
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Old 7th April 2009, 20:02   #9
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Quote:
Originally Posted by varunj View Post
Guys, I am quite new to this forum and this is my first post.

I am doing a research project on the car battery and consumption of the various units found in a car.

I want to understand some basics about the car batteries of a car (lets take a Maruti Esteem as an example)

1. What is the capacity of the battery (I believe this is measured in AmpHours?)?
2. What is the consumption of the various units inside a car:
a. Air conditioner
b. Cigarette charger
c. Headlights
d. Interior lights
e. Wipers
f. Radio
3. What would be the total power used by an LCD screen installed on the rooftop or the headrest, which draws 12V power from the battery at ~7 W?
4. Would this require a higher capacity battery to be installed?
5. Is there a chance that the LCD screen can drain the battery if a higher capacity battery is not installed?
6. Can an additional accessory like this reduce the lifetime of the battery? Is there any scientific way to test this?

Does anyone know anyone or anywhere, where I could attempt installing such a screen and testing something like this out, or to whom I could goto to get such information? Any relevant references/contacts would be appreciated.

Thanks a lot.

Regards,
Varun

Are you researching about how to minimise your power bills ? LOL .

On a serious note the 35 AH mentioned is for a new battery . In reality you might end up getting only 30 or 25 AH .

For a car battery the most important is CCA or cranking amps . That is typically a minimum of 150-300 AMPS for the starter motor to start the engine . All the other loads are not so important for a car battery unless and until you plan to stay in the car for extended periods when the car isnt started or running .
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Old 11th April 2009, 13:30   #10
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greatmana2000, su-47, vigsom, clevermax, thanks a lot for your answers. Extremely helpful.

I am doing a bit of research myself to understand what sort of effect the equipment inside a car has on its battery and on fuel consumption, when it is on.

What I understand from all your answers is that there is no effect on the battery (neither drain nor reduction of long-term life) if equipment is used while the car is switched on, since the power drawn for the equipment is from the alternator.

Now, what I understand of an alternator is that it is a simple device that converts mechanical energy (by connecting to the crankshaft) to electrical energy, and has two purposes: 1. To recharge the battery, 2. To power the devices with a constant voltage

So, I suspect that the alternator has the ability to produce a certain amount of energy, part going to the battery and the other part going to the devices. I want to know what this maximum amount of current is, and subsequently what a radio, AC, wipers, headlights, LCD screen use.

I assume that if you plug in enough devices into an alternator, it will use all the energy that the alternator produces, and then if it requires more, it will start drawing from the battery. I would really like to know how this can be determined as well. I understand this is not something I will probably reach, but really would like to get this info.

Would it be measured in Amps, Watts, CCA?

Let me know if I have got this completely wrong, because as you may have realised I'm a complete novice when it comes to this stuff

All the help is greatly appreciated.

V.
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Old 14th April 2009, 18:17   #11
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Varun,
Since you are trying to run the LCD when the engine is on, you need to look at the alternator capacity rather than the battery capacity. The alternator capacity is denoted in Amps.

Calculate the overall accessory loads (LCD, head lights etc...) and check if the alternator can support these loads. If not you might need to go for a higher alternator.

Good luck
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Old 15th April 2009, 14:28   #12
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Quote:
Originally Posted by varunj View Post
....Rehaan I looked at the articles, but didn't really find the information I was looking for....

...Basically, what I am looking for is a breakdown of use...
Varun,

Take a look at this link, specifically post #122 by me. It gives you a basic overview, as well as shows you how to calculate load (Amps) if you know the Watts drawn etc.

It also explains the balancing act between the alternator and battery, which you had a Q about.

http://www.team-bhp.com/forum/4x4-of...tml#post887688


Quote:
Originally Posted by vigsom View Post
...the power consumption in amps could be closely related to the fuse rating - if the fuse says 10A,80% of that would be the max current drawn....
Thats a good way to know the maximum possible current on those circuits - afterall, if the circuit was pulling more current the fuses would just blow.

Alternatively, and more accurately :

1) Get a multimeter (put it on the 10A max unfused setting. Or if you can get an ammeter which can handle higher amperage that would be better)

2) Be VERY careful not so short circuit anything, the car battery can pump out MAJOR amperage and if shorted it can cause serious injury.

3) Remove the fuse for the circuit you have chosen to test (eg. lighter socket). Make sure the fuse is not rated for more than your multimeter can handle (usually 10A on the unfused port).

4) Use your multimeter (connect in series) in place of the fuse to complete the circuit (ideally, in series with the fuse as well for safety) and run your equipment.

5) This should give you an accurate/real reading. Repeat from step (3) for every other circuit.

You can also do this in-line closer to each device (on its individual circuit) if you want to get specific power draw figures, since sometimes multiple accessories are clubbed on just one fuse in the fusebox in parallel. Though this might involve messing with existing wiring.

** Guys please check if there is something i might have overlooked (safety wise etc) **

Quote:
Originally Posted by varunj View Post
1. What is the capacity of the battery (I believe this is measured in AmpHours?)?
I'm not sure about the OEM battery, but you can get other batteries which have a much higher capacity (AH), which i think are popular with ICE guys having heavy setups.

Quote:
Originally Posted by varunj View Post
2. What is the consumption of the various units inside a car:
a. Air conditioner
b. Cigarette charger
c. Headlights
d. Interior lights
e. Wipers
f. Radio
Discussed 2 ways to figure this out above (in link & w/ ammeter)

Quote:
Originally Posted by varunj View Post
3. What would be the total power used by an LCD screen installed on the rooftop or the headrest, which draws 12V power from the battery at ~7 W?
Once again, do the math from the link posted at the top of my post.
(Car battery voltage can be anywhere from 11-14 volts, so keep this variation in mind for your calculations.)

Quote:
Originally Posted by varunj View Post
4. Would this require a higher capacity battery to be installed?
No. It is not a requirement.
A higher capacity battery might only give you an extra few minutes/hours IF you plan to run the LCD with your car off for a loong time.

Quote:
Originally Posted by varunj View Post
5. Is there a chance that the LCD screen can drain the battery if a higher capacity battery is not installed?
Only if the device is putting so much extra load on the system that it is sucking up all the current from the alternator, and therefore not letting the battery get any charge.

Quote:
Originally Posted by varunj View Post
6. Can an additional accessory like this reduce the lifetime of the battery? Is there any scientific way to test this?
Im unsure.

Usually different chemistries have their own likes and dislikes when it comes to usage.

For eg. If you plan to use the system a lot without the car running, and run the battery down to almost 15-25% regularly, there are "deep cycle" batteries that are better suited to this purpose. (These are used for inverters / solar powered homes etc).

Li-Pos for example hate to be discharged below a certain voltage, as it can damage the battery.

As far as NiCads, i think they love to be discharged at a high rate.

They all have their own personalities - and i'm no expert, so check these two sites out :

Welcome to Battery University
batterydata.com


Quote:
Originally Posted by varunj View Post
Does anyone know anyone or anywhere, where I could attempt installing such a screen and testing something like this out, or to whom I could goto to get such information? Any relevant references/contacts would be appreciated.
Are you interested in buying? Or just testing??

Theres a ton of these shops at opera house, in that lane full of car stuff.
Theres also "Rhyme n rhythm" in colaba, near sasoon dock. (google them)
+++ some more places others can mention...


Quote:
Originally Posted by varunj View Post
...I am doing a bit of research myself to understand what sort of effect the equipment inside a car has on its battery and on fuel consumption, when it is on.
I know there is a thread somewhere regarding the effect of electrical load on Fuel Efficiancy, or something like that. You're gonna have to search because i can't seem to find it. (Maybe it has to do with faster processors in ECU affecting FE?)


Quote:
Originally Posted by varunj View Post
So, I suspect that the alternator has the ability to produce a certain amount of energy, part going to the battery and the other part going to the devices. I want to know what this maximum amount of current is,
Quote:
Originally Posted by varunj View Post
... would really like to know how this can be determined as well. I understand this is not something I will probably reach, but really would like to get this info. Would it be measured in Amps, Watts, CCA?
Amps. Look up CCA to understand how it is different from Amps.

Quote:
Originally Posted by VeeTee
Since you are trying to run the LCD when the engine is on, you need to look at the alternator capacity rather than the battery capacity. The alternator capacity is denoted in Amps.
Also keep in mind that the alternator output rating is not a constant. It will only provide that amperage when it is spinning at the desired RPM (probably not at engine idle).

cya
R

PS - are you kunals brother?

Last edited by Rehaan : 15th April 2009 at 14:30.
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Old 15th April 2009, 15:14   #13
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Varun, if you are basically thinking if the LCD will drain your battery, do not worry. I have a DVD HU, Amp, LCD and have even used the DVD/LCD with the engine off several times. I have never had the battery drain off. My battery is 4 years old & my car still runs fine. Hope that helps.
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