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Bronze Member Username: Bruhneedluv2Post Number: 91 Registered: May-04 | I went to this website http://www.a1bigaudio.com/electrical.htm and read this: Most alternators have about a 40 percent reserve capability. Order to determine how many in ampere of current you will have for your system; you will need to find out what your alternator is rated at. If you're not sure of the total amperage of your alternator, a good place to look is on the alternator itself. Most alternators have a metal tag stating the total average available. If you can't find the tag, check with the manufacture to find out the rated amperage. Once rated current of the alternator is determined, you need to multiply this number by .40 in order to determine the reserve current available for use with your power amplifier. For Example: Alternator = 80 Amps 80 x .40 = 32 Amps Please keep in mind this is an estimate only not exact science. It is best to get your electrical system tested by a professional to determine electrical systems true capabilities. Calculating Amplifier Current Demands By using the fuse value of the car amplifier you can get a rough idea of the amount of current draw the will be used under full output power. Although the full output rating is good to determine the total amperage draw in the system, it does not represent the true continuous or averaged amperage draw in the system. Listed below is a simple way in order to determine the approximate continuous current draw of your amplifier. 1.) Determine fuse value of the amplifier. 2.) Divide the RMS power Rating by the Peak power rating. Example: 50Watts RMS Divided by 100 Watts Peak Power = .50 (50%) Once you figure the percentage of RMS vs. Peak power, you multiply the fuse value of the amplifier by the RMS percentage. Example: If the amplifiers fuse value was 30A, then 30A multiplied by 50% would be 15A of continuous current draw. Upgrading your Electrical System Depending on systems current requirements vs. your electrical systems capabilities, you may need to upgrade your electrical system. For example, if you find that you headlights dim when you have your system cranked up when you are driving at night, this is a sign you should upgrade your electrical system. There is several different ways order to accomplish this; one way is to upgrade the alternator so that it has higher amperage output. Another way is to purchase a Capacitor. We recommend to consult your Car Audio Retailer to determine what is best for your system. IF this is true, then my stock alternator may be okay for the job and I may just need to get a cap. It only dims on the quick hits, but not on the continuous bass drops. Wierd to me I guess. Im just sharing what I found. the only thing that I did not see from the answers that the pros gave in here is the Calculating Amplifier Current Demands section. Anyone may have, but I searched for about an hour and did not find it in here. |
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Silver Member Username: JayjLouisiana USA Post Number: 330 Registered: May-04 | Get you a DMM and check your currents when you play the system. Then see what you come up with. If it only dims the lights when it hits really hard then a cap will help you. You should need about 1 Farad per 1000watts. Good Luck |
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Gold Member Username: GlasswolfNorthWest, Michigan USA Post Number: 4045 Registered: Dec-03 | actually that 40% reserve isn't always accurate. a lot of cars, especially imports and cars with heavy electrical use for things like power everything tend to use very close to the stock alternator's full output. I've seen a 200 watt amp cause a car with stock alternator to stall out at lights. Scary thing was he didn't even have subs.. just a 4 channel amp for his mids/highs. I disagree with some of what that guy was saying, but I wrote my own info on charging systems. this is my view: http://www.wickedcases.com/caraudio/charging.html |
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Gold Member Username: GlasswolfNorthWest, Michigan USA Post Number: 4046 Registered: Dec-03 | oh, please also note that this fuse rating nonsense is useless because firstly, there's no guarantee that the fuse rating for the amp is accurate, and secondly, even if it is accurate, it's based on the full peak output of the amplifier (in most cases two ohms) and if you're running the amp at 4 or 8 ohms, you'll only be drawing half or a quarter of the current respectively. These things need to be considered. The best way to find current draw is check the amp's manual or website to see what's listed for peak current draw. figure that's based on full output and if you use the amp at a higher load, then divide appropriately to compensate. |