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How to calculate (predict) voltage drop? Can somebody check my math?
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Join Date: Oct 2011
Re: How to calculate (predict) voltage drop? Can somebody check my math?
I've done a bit of thinking about this and I think I have it semi figured out.
We can treat the battery and the alternator as both a voltage source, and a current source, which is shown in the pic above.
Basically, we have two scenarios. When load is less than the alternators production, and when the load is greater than it.
When load is less than the alternators production, the alternators voltage dominates the circuit since it is higher. The current will flow from the alternator up and and right. It will then split to meet the load requirement(the resistor in this circuit, or the sub in real life). Excess current will flow through the battery charging it. The battery here can actually be assumed to be a load.
When the alternator cannot supply enough current, the battery will also become a current source. Since there is a general rule that voltage cannot be different at a single point, I assume the alternator's voltage must drop. This will allow both the alt and battery to produce the current being sent to the load, in picture 2. In this scenario, we can treat both sources as having the voltage of the battery.
I'm not too knowledgeable in alternator voltage-output behavior, but I have to assume output voltage starts to suffer as current really starts to increase. Maybe somebody will be able to toss a few words in on that topic, and I can revise what I've written
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