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Thread: Alternator Questions |
    
Silver Member Username: Adelphia83
Colorado Springs,
CO
USA
Post Number: 107
Registered: May-05
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| Posted on Saturday, October 18, 2008 - 11:37 pm: |
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Why does one need an upgraded alternator when going high power (> 1000rms)? Isn't the vehicle battery able to deliver the additional current?
I understand that battery voltage is ~12v vs the 14.4v supplied by the alternator. Sure, this decreases power output on amps w/ unregulated supplies. But if you factor that in (buy your amp with +20% power), wouldn't the battery suffice? The battery is more than capable of supplying huge amounts of power upon demand (e.g vehicle starter).
The amp is never going to run 100% duty cycle, unless you've got a sine wave at the input. So it's likely that the battery will be charged intermittently when power demand for the amps is low.
Is any of this making sense? I could be barking up the wrong tree, just wanted to get more info on the subject. TIA! |
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Bronze Member Username: Wickedbass
Nashville,
Tn
Post Number: 17
Registered: Jan-08
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| Posted on Sunday, October 19, 2008 - 12:04 am: |
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It takes power to make power.
Maybe this will help...
http://www.termpro.com/articles/electsys.html |
Gold Member Username: Nd4spd18
Philadelphia,
PA
Post Number: 8581
Registered: Jul-06
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| Posted on Sunday, October 19, 2008 - 12:25 am: |
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Problem is with bass heavy music there is not enough time for the alternator to recharge the battery in between current draw spikes when the bass hits.
The HO alternator charges the battery 2x-3x as fast, makes a big difference. Of course you also need a good high capacity battery to store that current.
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Silver Member Username: Adelphia83
Colorado Springs,
CO
USA
Post Number: 111
Registered: May-05
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| Posted on Sunday, October 19, 2008 - 12:48 am: |
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A lead acid battery at full discharge under load should still produce near 11v-- Therefore I see no need in upgrading electrical components unless you find the battery being dead (or close) after extended periods of operation. Am I correct? |
Gold Member Username: Nd4spd18
Philadelphia,
PA
Post Number: 8590
Registered: Jul-06
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| Posted on Sunday, October 19, 2008 - 02:11 am: |
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Look at it like this.
Amplifier is drawing more current than alternator can supply (on average).
Battery has to pick up the slack and discharge current. The more current taken from the battery the more the voltage drops.
And since you're taking out more than you're putting in, well it shouldn't be hard to understand. BTW drops to 11v and under is pretty bad.
Think about it, if high capacity batteries and HO alternators were'nt needed would people buy them?
Edit: That may be a bad analogy now that I think about it, since capacitors don't do jack, and people buy those. But thats another issue. |
Gold Member Username: N2audio
Lawrence,
Ks
USA
Post Number: 1641
Registered: Mar-04
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| Posted on Monday, October 20, 2008 - 12:29 am: |
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a lot of bad things start to happen when the alt is barely big enough to keep the battery charged, as the voltage falls everything demands more current. It's just a bad situation to get into.
1000 on most stock systems will work ok. You start to get 1500+ and you're probably going to find the limit of a lot stock charging systems -- assuming you like to blast it now and then. |
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