Jan
Ok,I have a couple of questions.Ok,Im a High voltage Electrician and In my line of work one way to find amperage (when giving at least 2 factors of the equation)is dividing the Total wattage by the volts…So I assume its the same in DC voltage….Then given these factors in my vehicle.I have a total of 1500watts im using(maybe less,Im doing worst scenario).Dividing that with 14.4Volts gives me a total of 104.2AMPS.
Is this the correct way to figure the amperage?
If so…..then will my factory (Dodge truck)136amp alternator be enough (I have the basic truck with no extras)to Supply my needs So long as I upgrade the big 3(wire size,Deep cycle battery maybe caps)….I think it will ,but are there other factors I should be aware of?
Answer:
First, is the 1500w max or rms power? You should use the rms power of the amp and not the max.
That is correct except you want to include the efficiency of the amp in the equation. Depending on the class of your amp will depend on how efficient it is, as well as other factors. Just to be general I will say 65% efficiency. So you would take the 1500w/0.65 = 2308w. That means you would need to give the amp 2308w in order to have enough power for the amp. Now doing ohm's law 2308watt / 14.4V = 160A.
If you are not using rms values then it will be less. Also if you have a more efficient amp, class d has about 80% effficiency, the number will be lower.
You also are going to have to add the fact that you still need to run the rest of your electronics on your car. You could do with the alternator you have now but in order to get the full power out of your amp you will need a 200A alternator.
Big 3 and battery upgrades are good idea along with an alternator upgrade. Alternator is the most important though. Don't waste your money on a cap.
Good Luck!!!
Edit: koyaanisqats1, adding a second battery is not a good idea. That will put more strain on the alternator because now it has to charge two batteries and not just one.
Answer:
Power = voltage x current or Watt = volts x amps or P = V I
Answer:
Yes, all your volt/amp/watt/resistance formulas are the same in HV as they are in automotive DC. Also, work your calculations at 14.4v, 12v and 10v so you have the full range of possible scenarios.
The 1500w (assuming that's the correct value) will be your peak draw. Honestly, you will never pull that much power for any major length of time. But it may get close during a hard bass hit. Your alternator will most likely be sufficient for normal listening. But if you really crank the volume, you could starve your amp if the alternator maxes out. (the car draws a good 10-50A from the alternator while it's running. and if you run the in-glass defrosters, add another 30A easily) Depending on the amp, it could be damaged if the voltage drops too far.
The best way to go if you think there isn't enough current is to either upgrade the alternator or add a second battery and be sure the car is running when playing the stereo loud. Also add a 1 farad or more capacitor to the power leads of the amp as close to the amp as you can. This will improve the transient response required to produce clean bass notes at high volumes
Answer:
it should be enough since normally your battery will power accesories and the alternator just mainly powers the engine requirements until its required to divert some energy back to the battery for things like lights stereo and such
Answer:
Most Amps are sort of fradulent, they say 1500Watts on the box, and usually that means maximum (peak for a split second) which means diddily squat in the real world. You would need to look for the RMS rating of the amp, this RMS rating will coincide with the impedance of your amp. eg.) 400 Watts RMS into 4 ohms or 800 watts RMS into 2 Ohms
Check the RMS. Take the watts and divide by 12 (this will allow for some margin for error compared to dividing by 14.4 volts)
Then you need to think of all your trucks electronic systems, EG.) fan, radio, headlights, fuel pump, etc.
Also upgrade your "big 3" this will improve current flow.
the big 3 is: negative battery to chassis; negative chassis to engine; positive alternator charge wire to battery.
Use 1/0 copper welding cable for the big 3.
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