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Old 4th June 2011, 21:01   #16
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Default Re: Car Battery/alternator capacity query

@jinu joseph
First step should be to actually measure (not just calculate) amperes drawn by your ICE setup when fully cranked up.

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Sutripta
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Old 6th June 2011, 01:44   #17
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Default Re: Car Battery/alternator capacity query

100 amps I had no idea these ICE setups consumes so much power. In my car while idling and both the hedlights on high beam (2x130w) I measured the battery voltage it was close to 14.7 v so not even close to any charging problem. But this is only like 22 amps and I was worried I might be overloading the alternator.
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Old 6th June 2011, 21:29   #18
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Default Re: Car Battery/alternator capacity query

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100 amps I had no idea these ICE setups consumes so much power.
Something I'd like confirmed too.

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Old 6th June 2011, 21:46   #19
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Default Re: Car Battery/alternator capacity query

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100 amps I had no idea these ICE setups consumes so much power. In my car while idling and both the hedlights on high beam (2x130w) I measured the battery voltage it was close to 14.7 v so not even close to any charging problem. But this is only like 22 amps and I was worried I might be overloading the alternator.
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Originally Posted by Sutripta View Post
Something I'd like confirmed too.

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Sutripta
100A would be about 1200W assuming nominal voltage of 12V.

The 1000 watt (approx 83.3 A @ 12V) rating can be RMS, continuous or peak power and into single, dual or quad channels depending on the amp.

Reliable ratings are RMS or continuous power i.e. without the circuit clipping. Peak power output is, well, peak which can be 3-4 times RMS output.

This amp pumps 1008W RMS into 2 ohms - probably for a sub woofer: Bazooka MGA11000H Mono subwoofer amplifier — 1008 watts RMS x 1 at 2 ohms at Crutchfield.com It is protected by a minimum 120A fuse which is the size of the main alternator fuse in my car.

Now THIS is the kinda amp that would mandate an alternator and wiring upgrade. Remember, you add DSPs, 4 channel amp and the source you are crossing another 50A. Our sub 2 litre Indian car engines will probably die if fixed with alternators powerful enough to run this set up PLUS run the car's ignition and other loads.
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Old 6th June 2011, 22:05   #20
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Default Re: Car Battery/alternator capacity query

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Reliable ratings are RMS or continuous power i.e. without the circuit clipping. Peak power output is, well, peak which can be 3-4 times RMS output.
RMS and continuous, I would think.

What is the rail voltage of these systems? How is it achieved?

It would be educative if someone would actually measure the power drawn by these all singing all dancing setup. jinu_joseph?

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Sutripta
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Old 6th June 2011, 22:18   #21
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Default Re: Car Battery/alternator capacity query

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Originally Posted by Sutripta View Post
RMS and continuous, I would think.

What is the rail voltage of these systems? How is it achieved?

It would be educative if someone would actually measure the power drawn by these all singing all dancing setup. jinu_joseph?

Regards
Sutripta
Yes both are reliable measures. The reason I put an 'or' is amp makers generally specify one of them. For e.g. Infinity - Car Audio

This is the amp I have in my car - a 300w RMS (75w x 4 channels) x 4 Ohms set up. And this is a decent run-of-the-mill 4 channel amp.

They haven't mentioned Continuous power or, heavens forbid, PMPO.
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Old 7th June 2011, 15:09   #22
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Default Re: Car Battery/alternator capacity query

There is one more thing in this discussion - the average current consumption of ICE is not a constant. In other words, the manufacturer of an ICE tells you the maximum current it will draw under full load into the specified load with a constant tone 1 - 2.5 kHZ. But our music is not constant and so the load is never the maximum current unlike other lighting/AC loads.

You could do with high powered amps without overloading the supply - as long as you don't listen always in high volume.
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Old 7th June 2011, 20:44   #23
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Default Re: Car Battery/alternator capacity query

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Originally Posted by R2D2 View Post
Yes both are reliable measures. The reason I put an 'or' is amp makers generally specify one of them. For e.g. Infinity - Car Audio

This is the amp I have in my car - a 300w RMS (75w x 4 channels) x 4 Ohms set up. And this is a decent run-of-the-mill 4 channel amp.
Hi,
Still don't get RMS or continuous.

What current will your system draw when playing normal source at full volume?

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Sutripta
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Old 7th June 2011, 21:05   #24
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Default Re: Car Battery/alternator capacity query

Quote:
Originally Posted by Prowler View Post
There is one more thing in this discussion - the average current consumption of ICE is not a constant. In other words, the manufacturer of an ICE tells you the maximum current it will draw under full load into the specified load with a constant tone 1 - 2.5 kHZ. But our music is not constant and so the load is never the maximum current unlike other lighting/AC loads.

You could do with high powered amps without overloading the supply - as long as you don't listen always in high volume.
Quote:
Originally Posted by Sutripta View Post
Hi,
Still don't get RMS or continuous.

What current will your system draw when playing normal source at full volume?

Regards
Sutripta

Assuming a 50% efficiency level for the amp it would draw around 600w or 50A at full blast with peaks lasting only ms going to around 3 times as much. Now before someone asks why doesnt the fuse below - well, it is that millisecond timing of those peaks in the music that does not cause the fuse to blow.

Add the source which AFAIK pulls around 3-4A as I don't use the onboard amp you are looking at around 53-55A at full blast at upto 155A at peak for ms durations. My amp is protected by a humble 40A fuse inline in the power cord from the battery to the amp terminals.

As Prowler correctly points we dont use full volume all the time and thats why the fuse won't blow. I cant bear to turn up the music beyond moderate levels. I'd say my entire ICE pulls around 8-10A MAX (guesstimate again) at my normal listening level.

PS - I am just quoting from theory and guestimating. Have not used an ammeter to measure the current flow.

Last edited by R2D2 : 7th June 2011 at 21:09.
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Old 7th June 2011, 21:31   #25
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Default Re: Car Battery/alternator capacity query

^^^
Hi,
So the fuse (even if SloBlo) will blow if you turn up volume to max for a few seconds? Does it?

Regards
Sutripta

Last edited by Sutripta : 7th June 2011 at 21:35.
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Old 7th June 2011, 21:47   #26
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Default Re: Car Battery/alternator capacity query

They probably use slow blow fuses to prevent frequent blowouts.

Frankly I haven't tried pumping up the volume anywhere over what I think is say around 25-30%, that too when the setup was being tested shortly after install. Full volume - I dare not go that loud in a close environment like a car.
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Old 8th June 2011, 21:48   #27
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Default Re: Car Battery/alternator capacity query

^^^
Hi,
Asking you to sacrifice a fuse for the greater good! (Knowledge for all ...).

SloBlo is normally more for handling inrush current.

Supposing in your environment (ie same car, speaker, choice of source, volume level), you replaced your current amp with one of say double the power. How much would the current consumption increase by?

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Old 8th June 2011, 22:50   #28
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Default Re: Car Battery/alternator capacity query

Quote:
Originally Posted by Sutripta View Post
^^^
Hi,
Asking you to sacrifice a fuse for the greater good! (Knowledge for all ...).

SloBlo is normally more for handling inrush current.

Supposing in your environment (ie same car, speaker, choice of source, volume level), you replaced your current amp with one of say double the power. How much would the current consumption increase by?

Regards
Sutripta
This seems to be a trick question

Now the catch is same environment (speakers, source et al) with same volume level - well, for the same volume level (loudness) I'd say it would be the same power consumption as my current amp all other things, except power capacity of the new amp, being equal including amp power efficiency etc.

As for sacrificing a fuse..I'd have agreed but it would take something incredibly stupid to blow a 40A or the 32A inbuilt 'blade' power fuse when the amp is mounted and operating in the car. Sorry mate, I aint biting.
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Old 9th June 2011, 09:52   #29
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Default Re: Car Battery/alternator capacity query

^^^
Hi,
Don't think the fuse would have blown.

Wasn't a trick question. Wanted to highlight the fact that though it's important and reassuring to know (and actually measuring would be more reassuring than 'calculating') the power drawn by ICE systems, it is not something to get paranoid about.

Maybe this thread should be shifted to the ICE section.

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Sutripta
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Old 10th June 2011, 09:27   #30
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Default Re: Car Battery/alternator capacity query

The terminal voltage of an alternator is proportional to its rotational velocity. I would therefore be afraid, very afraid, to connect this to sensitive electronic equipment. Of course one can build an electronic gadget with its own condenser and regulator to work directly from an alternator; but who would want to do this, and for what purpose? Guys, the battery is like the overhead tank on your building. It supplies the flow irrespective whether the alternator is fast, slow, or stopped. The primary function of the car electrical system is to run the engine. It is therefore not advisable, for your own convenience, to use certain energy guzzling equipment when the battery capacity is restrictive. The job of the alternator is to replenish the battery, period.

If one is inclined to use up a lot of electrical energy, then one can build a set up to to charge the batteries from mains supply, rather than wasting fossil fuels, IMHO.

Most of electrical power in an amplifier is utilized to drive the low-frequency speakers (woofers). But music at 1000W RMS ? Gosh, isn't that too much for normal human ears? Would not one require Teflon coated ear-drums to enjoy that kind of sound output; especially in a small enclosure like a car?
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