i need help with capacitors

[Grinder1989 5,000+ posts]

At the moment I'm running a 140 amp alt, a decent battery and the big 3 and power and ground wire in 4 gauge. I have a sundown 1500 and at full volume i have little drop. $200 for an alt and a battery. If a person who knows nothing about car audio is told they have to buy a capacitor for $150 by some moron at circuit city, they'll buy it. Caps make companies money but don't do much for the people that don't know.

 

[SQChevy 10+ year member]

A capacitor lessens the load on an alternator. It keeps from pulling big surges when the sub hits hard. It would be better to upgrade your alternator so a cap isn't needed. It is better for the overall system. It will work and keep lights from dimming and such, but even when there is a big draw it still will stress the alternator.

 

[mrogowski 5,000+ posts]

A capacitor lessens the load on an alternator. It keeps from pulling big surges when the sub hits hard. It would be better to upgrade your alternator so a cap isn't needed. It is better for the overall system. It will work and keep lights from dimming and such, but even when there is a big draw it still will stress the alternator.

This is not correct. Having a capacitor inline is just like having another load. The alternator will not only have to provide power to the amplifier but will also have to charge the capacitor, which will demand the same if not more current than the amplifier itself.

An alternator is designed to supply current to the electrical system. It is no different than the breaker box in your home. You will not see electricians placing power storage devices to provide more power to a home. You will however, see them replace the breaker box (and main wiring) with a larger unit capable of supplying a higher current rating.

Best,

Mark

 

[Tiiimay 10+ year member]

This is not correct. Having a capacitor inline is just like having another load. The alternator will not only have to provide power to the amplifier but will also have to charge the capacitor, which will demand the same if not more current than the amplifier itself.
An alternator is designed to supply current to the electrical system. It is no different than the breaker box in your home. You will not see electricians placing power storage devices to provide more power to a home. You will however, see them replace the breaker box (and main wiring) with a larger unit capable of supplying a higher current rating.

Best,

Mark

thats because in a home you dont suddenly turn on 50 more apliances than you normaly do, for a half second burst. and in a home you have for all practical purposes a limitless supply of energy.

a capacitor will not act as a load, it will charge when extra energy is available. otherwise current will run right through it, yet when energy is in high demand it will deliver it at a extremely rapid rate to an extent your alternator will never do. you can get a big enough alternator that your sub can never demand too much, but that doesnt make a capacitor not a usefull item. There's a reason they exist...

 

[PSturmer 10+ year member]

those hc600's are good little things. just installed one in a friends car. i have used caps before and this hc does the job a thousand times better.

 

[Qbenjamin 10+ year member]

a capacitor will not act as a load, it will charge when extra energy is available. otherwise current will run right through it, yet when energy is in high demand it will deliver it at a extremely rapid rate to an extent your alternator will never do. you can get a big enough alternator that your sub can never demand too much, but that doesnt make a capacitor not a usefull item. There's a reason they exist...

X2. Well put.

 

[Grinder1989 5,000+ posts]

a capacitor will not act as a load, it will charge when extra energy is available. otherwise current will run right through it, yet when energy is in high demand it will deliver it at a extremely rapid rate to an extent your alternator will never do. you can get a big enough alternator that your sub can never demand too much, but that doesnt make a capacitor not a usefull item. There's a reason they exist...

Not well put. If a capacitor will not act as a load then what will it be? non existant? Everything connected to an electrical system that has current ran through it will act as a load. On top of that if your blasting away at full volume how would the cap recharge fast enough to keep up with the energy demand? They're useless to 90% of the people that have subs.

 

[donpisto 5,000+ posts]

I definitely agree with you on that 1. I laugh at people who try to run 1K plus watts off of their stock electrical system plus a CAP......

I sorta have done that. I was running a Treo SSX 1500.1 off an hc 1400 and the big 3 with a 90A stock alt...didnt have that much dimming at full tilt....then i dropped in a soundstream xxx 6500 and thats when i had problems, with the car off that is. i had quite a bit of dimming with the car on, but it help up somewhat decently at full tilt.

To those who say caps are useless, well I can say for myself, I think the same. Though they do something as someone said, but not all that much. It takes some time for it to store the energry and then it has to release what it has stored. Every time a bass note hits it has to give off what it stored. Honestly, caps are useless as far as a cost comparison to a battery goes. An HC 600 will be much more sufficicent and doesnt cost all that much more. Big 3 would be the best way to start off, then a battery, then an alternator (of course this is doing it the cost effective way). It would be best to add possibly a second battery if you're putting out quite a bit of power.

 

[Qbenjamin 10+ year member]

I sorta have done that. I was running a Treo SSX 1500.1 off an hc 1400 and the big 3 with a 90A stock alt...didnt have that much dimming at full tilt....then i dropped in a soundstream xxx 6500 and thats when i had problems, with the car off that is. i had quite a bit of dimming with the car on, but it help up somewhat decently at full tilt.
To those who say caps are useless, well I can say for myself, I think the same. Though they do something as someone said, but not all that much. It takes some time for it to store the energry and then it has to release what it has stored. Every time a bass note hits it has to give off what it stored. Honestly, caps are useless as far as a cost comparison to a battery goes. An HC 600 will be much more sufficicent and doesnt cost all that much more. Big 3 would be the best way to start off, then a battery, then an alternator (of course this is doing it the cost effective way). It would be best to add possibly a second battery if you're putting out quite a bit of power.

As with any and everything, their will always be better alternatives. Caps are not useless, if they are used correctly, and in conjunction with a bigger battery or alt.

 

[donpisto 5,000+ posts]

As with any and everything, their will always be better alternatives. Caps are not useless, if they are used correctly, and in conjunction with a bigger battery or alt.

Right, but multiple batteries would do the job much better. I'd look into batcaps as well. I bought a cap once, never used it and probably never will.

 

[mrogowski 5,000+ posts]

a capacitor will not act as a load, it will charge when extra energy is available. otherwise current will run right through it, yet when energy is in high demand it will deliver it at a extremely rapid rate to an extent your alternator will never do. you can get a big enough alternator that your sub can never demand too much, but that doesnt make a capacitor not a usefull item. There's a reason they exist...

I'm sorry, I see no reason. In my car I have a battery and an alternator. Whatever the alternator cannot instantaneously deliver, the battery will. That's what its there for. Oh yeah, and to start the car of course.

Now, lets take your analogy. Your cap is fully charged when all the energy is sucked from it 'at an extremely rapid rate' as you put it. So, your cap went from full energy to zero. Now it has to charge.

Where does it get its energy to charge from?

 

[profundus-sanus 10+ year member]

Not well put. If a capacitor will not act as a load then what will it be? non existant? Everything connected to an electrical system that has current ran through it will act as a load. On top of that if your blasting away at full volume how would the cap recharge fast enough to keep up with the energy demand? They're useless to 90% of the people that have subs.

the capacitors inherent resistance value, which coincidentally is greater than that of a wire, would make it the path of most resistance. So caps only charge when the amp isn't drawing current and only discharge when more current is being drawn than the power wire can supply. Realistically you can use a slightly smaller wire in conjunction with a cap.

Caps have a use when the required current is smaller than the alternators output capacity. If your constantly dropping to battery voltage then a cap is wasted space and money....You need to get an alternator.

I know from experience that caps do work. I ran a pa 4 farad cap and 4 guage to a opti2000d on a a stock 140amp alternator and the cap eliminated a .5 volt drop. Thats with the big three done in hyperflex 1/0. If i'm getting 0-.1 voltage drop on around 1900 watts something must be working.

To the op, whats your amp and other electrical setup? If its a real 4000 watt amp your going to need some serious alternator output.

 

[SQChevy 10+ year member]

If you don't have a capacitor and you are constantly using the sub heavy and hard it will cause your alternator to run at full speed and sometimes your system will try and pull more than it can provide. If you do this long enough your alternator will go out and in rare cases it can cause the alternator to catch fire. (Personal experience from idiots at Best Buy) It is there to keep the amp in power when it sub hits hard. During times when the amps are using a lot of power the capacitor will charge. I have around 2000 watt system and have a 200 amp alternator and I hardly get any drop in voltage in my system. I used to run a cap, but I didn't need it and it causes some noise in the system. Nothing extremely noticeable, but considering it's a competition vehicle it needed to be taken out.

 

[helotaxi 5,000+ posts]

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[Live4SkimLC 10+ year member]

Actually, i dont want to be involved in this.... haha, i'll just keep laughing