I was just wondering how much strain a system puts on your battery and alternator. I am planning on putting two 10's with 300w (probably actually 150w) and two 12's which I don't have an amp for yet (some where around 1000w). I also plan to run either 1agw or 4agw from the battery and then use a distrobution block to run 4agw or 8agw to the amps. Do you think this will wear out my alternator and whatnot? It's a 94 Bronco.

 

I could not give details and numbers, but I can give you the bottom line. We put one in my Sons Blazer, and if he listened for even 10 minutes without the vehicle running, the battery would be dead. This is a new battery with 960 cold cranking amps, and also a 75 watt Alternator. When the vehicle was running, if it was at 1500 RPM or lower, the Headlights would bright and dim in time to the Music. To answer the main question, yes, it puts a very high demand on your electrical system. Heavy wire, separate battery, heavy fuses will be required for anything above a normal system.

We installed a Second Battery just for his Stereo system, with an isolator. A stock 35 amp alternator just can not keep up with the system, and will toast it's self very quickly.

Also I do not know the real name for it, but they make a Capacitor that is the size of a flashlight to go in the positive feed for the Amp. This helps to store a charge, and keeps the Amp from burning it's self out, and puts less demand on the battery and charging system.

 

Aha! yes, a capacitor. I forgot to put one of those down on my shopping list. but, anyway...

Did the second battery do the trick? And, how and where, did you hook it up, if I might ask? And how does it recharge? Just by being in the system? I have always thought of doing that, but I didn't know it was actually done. I thought maybe those six pack-looking gell batteries would do nicely. Thanks.

Oh yeah... "isolator"... what is that?

 

Unless you cherish the idea of someday getting stuck with a dead battery, I highly suggest a second battery. My Son had to learn the hard way a couple times before he done it.

They make a batter isolator just for a second battery. You can find them at any parts store. The higher the amps/charge the better, but the higher the cost.

An isolator is like a Voltage Inverter. Instead of converting it to 110 volts, it senses the voltage in the second battery and keeps it charged. This is where the High amp alternator comes in. You need a high output alternator to keep it from toasting it's self by over working it when the stereo system is on.

Look at it this way. If you take a piece of tape, and place it over your mouth, then poke a small hole in it. You can breath, but not very good. Now picture trying to run with that tape on your mouth. Your going to black out very quickly. By trying to use a single battery with a low output alternator, this is what your doing to your system. You will fry amps, wires, alternators, batteries etc.

 

Thanks a lot. One more question and I'm on my way...

Are you suggesting I also get a different alternator?

 

i would suggest a damn good battery and and alt before a cap. all a cap does is help with those deep hits (its like a small baterry right near your amp)

Matt

 

FYI for general knowledge. Capacitors store a charge which is discharged when the amp is calling for current faster and in greater quanity than the battery can deliver it for those "deep hits". Electricity travels at the speed of light for all practical purposes. Caps can discharge quicker than a battery can thereby helping to eliminate the drain on the system that can happen to powerful stereos. An amps current draw is dynamic and is greatest when reproducing bass notes.

I know there is alot of confusion concerning caps and thought I would try to help some understand what they do.

 

A capacitator doesn't store the energy that is required. The idea is great but it is not executed. A cap will do a little bit, but I wouldn't go as far as to say it's like a little battery by the amp, it's not. It would be better to build up everything and spend money that way rather then wasting it on a cap. The only reason you see a difference when installing a cap is for a split-second, if that, the cap is drained.. if you upgrade your wires accordingly then you won't even see a difference with a cap.

The best way to start would be doing the Big 3 upgrade, which is upgrading the wire from battery negative to chassis, alternator to battery positive, and chassis to engine. Here's how to do it.

But to start off I would do the Big 3. After that, upgrade your battery to a Yellow-top Optima, then upgrade your alternator. You can spend $100 on a cap and still have a problem, or spend $150 on wiring and battery and fix that problem, then spend however much for the alternator you want.


For info on why you don't need a cap, click here.

 

I agree with the Big 3, they are critical, and you just can not have a quality system without them.

The Capacitor is just as vital. Like scafes explains, it is just as critical to have a good capacitor. I have 3 boys, all of which have put thousands of dollars into their systems. Like I mentioned before, I can not quote you the Tech Specs and model numbers unless it is the $$$$ to replace the Alternators and Batteries, and fryed wires. Look at it this way. With out the Capacitor to take the surge in power demand when you have those deep hits, then the Alternator/Regulator is taking the hits. Imagine your Alternator going from charge to no/charge in time to the music. How long will it last under those conditions.

If you do not think a capacitor will hold a charge, then charge one up on a ignition coil sometime, then throw it to someone to catch, then you better run like hell cause he is going to chase you down. Remember the old shop trick from High School.

 

It holds a charge but releases that charge within 1/1000 of a second. Read the post over why you don't need a cap (last link). I'm not trying to start a way here, and if you spend a lot of money on your system and have already upgraded alternator, batteries, wires, and everything, then a cap is properly used. But for most people it's a waste of money.

 

I agree. For most it could be a waste. Then again, for $100 you could look at it as insurance that your amp is going to get the current it wants and needs. The cap is constantly charging and discharging. It should be the last thing purchased.

I read over some of that long post. I don't think that guy understands that his alternator is just that, alternating. An alternator produces alternating current that is rectified to direct current. However, that DC is not pure and level like a battery. It is properly referred to as pulsing DC. The second half of the sine wave is "flipped over" and is travelling in the same direction as the first half. If filtering and other techniques are used, you could level this out. But I don't think autos do this.

Its been too long since I did much with the calculations. I don't see a cap having .017 ohms. That seems a little high to me, even figuring in reactance. The physical size of the cap doesn't really matter and to a lesser degree the Farad rating doesn't either. A 1MF cap could hold less charge, measured in coulombs, then a 1F cap if the 1F cap is larger.

But then again, I don't really care one way or the other and I am also not interested in starting anything. I am already way past my bedtime reading and writing this.

One final thought. My original reason for posting the first time. Caps discharge sooooo much faster then a battery can produce current. Electricity travels at the speed of light. Batteries are just a little slower than that. It is only needed at that split second when the amp needs it.

Good night.

 

To get back to the original question at hand:

A better alternator would be wise, and try and find one that puts out enough current (1 amp per 10 watts, plus the electronics/fan/lights).

I have, more than once, run 1500 watts on just an upgraded alternator and wires, for very long periods, with no problems what-so-ever (no light dimming). That doesn't mean that's what I would recommend, or that it would ever work again.

Whatever you decide to do, make sure you get input from every angle, and decide what best fits your wallet, abilities, and needs.

 

General idea but not exactly true. The reason for a capacitor is that it responds better to brief peak surges in current draw than a lead acid battery does because as load increases, battery efficency is lost due to internal resistance cause more of the power to be lost to heat and gassing. The best cure here would bea second battery and a cpapacitor bank of at least a few farads because it will actually extend battery life. Not best it make power (the capacitors) but because it greatly lowers the average draw on battery for amp (when capacitors are sized correctly for load) and improves its discharge efficency a lot. A capactor by design has very little internal power loss at high discharge rates. If you placed a old analog style amp meter on battery output and compared draw without caps and wwith them, you would see a big difference as the peaks draws would be much lows and the average drain would be a lot more steady.

 

[QUOTE=scafes]I agree. For most it could be a waste. Then again, for $100 you could look at it as insurance that your amp is going to get the current it wants and needs. The cap is constantly charging and discharging. It should be the last thing purchased.

QUOTE]
[QUOTE=scafes]FYI for general knowledge. Capacitors store a charge which is discharged when the amp is calling for current faster and in greater quanity than the battery can deliver it for those "deep hits". Electricity travels at the speed of light for all practical purposes. Caps can discharge quicker than a battery can thereby helping to eliminate the drain on the system that can happen to powerful stereos. An amps current draw is dynamic and is greatest when reproducing bass notes.QUOTE]

I get a kick out of seeing people paying $100 or more for these caps. Any idea what they cost the distributor?

Anyway, electricity does not travel at the speed of light - wish it did. Would make my life easier. The main purpose of the capacitor is to help reduce the "inductance" of the cables connecting the amp to the battery, and the "lag: or drop in battery voltage when hit with a near instantaneous heavy current demand. The capacitor acts as a "spring if you will, storing a small amount of current when the amp demand is low and returning it to the circuit as the voltage drops during the high current moment. It will only help during the "heavy instant" of a peak demand on the battery. The lighter the wire to the amp, the more "help" it gives. But the cap, the heavier wire, etc, are all only aids to reduce the main problem - voltage droop during high current demands. If you want the ultimate system, go with a 24v main system, and a 12 v 500 amp feed forward regulator at point of use. (Put it in the box of the truck). If you doubt the above, hook an oscilloscope on the +DC input terminal of the amp, connect the ground at the battery neg. terminal, and play some heavy metal at max volume. You might be surprised.....

 

All capacitors have what's called a ESR, Effective Series Resistance, and will vary depending on the materials used in the capacitor, as well as the manufacturer of the capacitor.