Capacitor - Battery
- Thread starter shootermain
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93 saturn sl2
10+ year member
CarAudio.com Veteran
you dont need a cap.
05AztecRed
10+ year member
Senior VIP Member
The three of them are the idiots... A cap. is essentially a battery... The only thing you would need is a high-output alternator to keep all your batteries charged...
jmanpc
5,000+ posts
CA.com Nostalgist.
a cap is unnecessary, because feeding a 2500D the energy from a cap is like feeding a lion a mouse.
- Thread Starter
- #6
Thats what I thought. I knew a cap is just a battery. I always used a cap for smaller systems. nothing like what i'm running. I was putting up a fight with him until the other 2 came in a butted in our conversation and it was like I didn't have the edge anymore. I don't run the system until i'm tuning or running it at a sound off. so i never knew if it was dimming my lights or not. But my voltage only went from 14 to about 13.5. didn't drop much. I was showing it off to him and he asked where my caps were. Thats what started it all.
helotaxi
5,000+ posts
Kilroy was Here
No one ever NEEDS a cap. Not EVER. There are actual solutions to voltage problems, and they don't include caps.
No one ever NEEDS a cap. Not EVER. There are actual solutions to voltage problems, and they don't include caps.
Not ever how can you say that. I think It would make sense if you would reword your thread That there are actually several different solutions to solving voltage problems, 1 could be upgrading your wire, or installing another Battery or a Capacitor. Because not everybody needs another battery or 2. or spending $400 on a H.O. Alternator.
Some only need a small or medium cap to keep there stereo sounding good.
Even though caps are just as expensive as batteries, but not everyone wants to put another Batt. in the trunk.
Not ever how can you say that. I think It would make sense if you would reword your thread That there are actually several different solutions to solving voltage problems, 1 could be upgrading your wire, or installing another Battery or a Capacitor. Because not everybody needs another battery or 2. or spending $400 on a H.O. Alternator.
Some only need a small or medium cap to keep there stereo sounding good.
Even though caps are just as expensive as batteries, but not everyone wants to put another Batt. in the trunk.
spoonraker
10+ year member
CarAudio.com Elite
No...you never need a cap...ever.
Here's a real quick explanation...
First of all lets reiterate some basic electrical theory. You need to know that current always flows from the highest electrical potential to the lowest. In other words, the source of power with the highest voltage will be what your system draws from.
Your alternator is the main source of power. It has the highest voltage, and it maintains that voltage until the load placed on the alternator is more than it can provide, in which case the voltage drops, very very very quickly.
A capacitor is not at all similar to a battery. A capacitor simply stores electricity, that is all. It will charge to the highest voltage on your system, whatever voltage your alternator puts out, and then do nothing until that electricity is drawn from the capacitor. A battery on the other hand actually creates electricity from chemical reactions. Both a battery and a capacitor have a limited life. A capacitor will drop volts VERY quickly, in less than a second a medium powered audio system will drop a capacitors voltage below that of the battery, which then stops any electricity from being drawn from the cap, since, again, voltage always flows from the highest electrical potential to the lowest. The battery, unlike the capacitor, can maintain it's voltage for a sustained period of time. Eventually it will drop volts too, but it lasts 1000x longer than a capacitor does.
So to put it very simply. Once your alternator is pushed too far, the current will be drawn from the capacitor since it was charged to the highest voltage, in about 1 second the capacitor will have dropped enough voltage that the load will then be placed on the battery.
So if you'd rather spend money on a capacitor to power your system for one second, go ahead, but just getting a better alternator will be a much better solution to your voltage problems.
My suggestion to you is to get a better alternator first. Upgrade your wiring to make sure it's being fully utilized. Then get a deep cycle battery to replace your red top, that way if you do slowly drain your battery, it won't be damaged at all since deep cycle batteries are designed to be completely discharged and recharged many many times.
Here's a real quick explanation...
First of all lets reiterate some basic electrical theory. You need to know that current always flows from the highest electrical potential to the lowest. In other words, the source of power with the highest voltage will be what your system draws from.
Your alternator is the main source of power. It has the highest voltage, and it maintains that voltage until the load placed on the alternator is more than it can provide, in which case the voltage drops, very very very quickly.
A capacitor is not at all similar to a battery. A capacitor simply stores electricity, that is all. It will charge to the highest voltage on your system, whatever voltage your alternator puts out, and then do nothing until that electricity is drawn from the capacitor. A battery on the other hand actually creates electricity from chemical reactions. Both a battery and a capacitor have a limited life. A capacitor will drop volts VERY quickly, in less than a second a medium powered audio system will drop a capacitors voltage below that of the battery, which then stops any electricity from being drawn from the cap, since, again, voltage always flows from the highest electrical potential to the lowest. The battery, unlike the capacitor, can maintain it's voltage for a sustained period of time. Eventually it will drop volts too, but it lasts 1000x longer than a capacitor does.
So to put it very simply. Once your alternator is pushed too far, the current will be drawn from the capacitor since it was charged to the highest voltage, in about 1 second the capacitor will have dropped enough voltage that the load will then be placed on the battery.
So if you'd rather spend money on a capacitor to power your system for one second, go ahead, but just getting a better alternator will be a much better solution to your voltage problems.
My suggestion to you is to get a better alternator first. Upgrade your wiring to make sure it's being fully utilized. Then get a deep cycle battery to replace your red top, that way if you do slowly drain your battery, it won't be damaged at all since deep cycle batteries are designed to be completely discharged and recharged many many times.
joetama
5,000+ posts
The British Ear
You are all right and you are all wrong... //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif
I agree 99.9% of the time people use Capacitors for the wrong reasons and don't really need them...
They are meant for 'stiffening' ie for short (VERY SHORT) impulse voltage drop issues.
Also, a battery only produces its own charge for a very short period. If batteries generated their own power by under going a great chemical reaction then we wouldn't need to charge them. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif
Go to this link...
http://falstad.com/circuit/
Import this data in the import menu under file.
$ 13 5.0E-6 30.96768661252054 30 5.0 50
v 64 320 64 192 0 0 40.0 14.0 0.0
r 144 144 144 224 0 5.1228
d 144 224 144 288 0
d 144 288 144 352 0
w 64 192 64 112 0
w 64 112 144 112 0
w 144 112 144 144 0
w 64 320 64 368 0
w 64 368 144 368 0
w 144 368 144 352 0
t 144 224 192 224 0 1 0.7888489281771617 0.7891001865734992
r 192 240 192 368 0 7.0E-4
w 144 368 192 368 0
p 192 112 192 208 0
w 192 208 224 208 0
w 224 208 224 368 0
w 224 368 256 368 0
c 336 144 336 272 0 100.0 13.993927120418611
c 480 144 480 272 0 1.0 13.997831899442744
r 560 144 560 272 0 0.05
r 336 272 336 288 0 0.0010
r 384 272 384 288 0 0.0010
r 480 272 480 288 0 1.0E-4
w 560 112 560 144 0
w 336 288 336 368 0
w 384 368 336 368 0
w 480 288 480 368 0
w 480 368 384 368 0
w 560 272 560 368 0
w 560 368 480 368 0
s 384 112 480 112 0 false false
s 336 112 384 112 0 false false
s 256 112 336 112 0 false false
s 336 144 336 112 0 true false
s 384 144 384 112 0 true false
s 480 144 480 112 0 true false
p 256 112 256 368 0
w 256 368 336 368 0
w 384 368 384 288 0
w 144 112 192 112 0
S 192 112 192 64 0 true false 0
r 208 64 256 64 0 0.0025
w 256 64 256 112 0
c 384 144 384 272 0 100.0 13.994026263554805
s 480 112 560 112 0 true true
o 0 64 0 2 20.0 1.6 0
o 17 64 0 2 20.0 9.765625E-5 1
o 17 64 0 1 10.0 9.765625E-5 1
o 43 64 0 2 20.0 9.765625E-5 2
o 43 64 0 1 10.0 9.765625E-5 2
o 18 64 0 2 20.0 9.765625E-5 3
o 18 64 0 1 10.0 9.765625E-5 3
o 32 64 0 1 7.62939453125E-5 9.765625E-5 4
o 19 64 0 2 7.62939453125E-5 9.765625E-5 5
o 19 64 0 1 7.62939453125E-5 9.765625E-5 5
o 36 64 0 2 20.0 9.765625E-5 6
Play with it a little bit. Especially with short impulses on the loads. (CLICK ON THE SWITCH TO CONNECT/DISCONNECT)
(BTW, these numbers are just set up to show my point and that is it.)
Basically... The current limiter circuit simulates a 250 Ampere alternator. The 100F Capacitors with the 1m Ohm resistors act like batteries (so to speak). The small capacitor acts like a normal capacitor with a much lower resistance and a quicker load reaction time than the battery.
Here are the steps to figuring out this stupid question.
1) Disconnect all the caps and batteries so you can only run on the alt. Click the load on and off several times and watch what happens to the voltage and the current.
-What you find is a instant voltage drop because of the load change and a pull of 250 ampere on the alt.
2)Connect only the capacitor. Test under load.
-What you will find is a slight 'stiffening' for short impulse loads. If you do this step correctly you will find that during short impulses the capacitor reacts to the change in load and the alt will not pull 250 amperes. However, if you leave it on long enough the capacitor will no longer be of no extra help.
3) Connect the one of the batteries. And test under load.
-You will find a much increased stability in the voltage. But, if you disconnect the capacitor you will find an increase in the current sent form the alternator.
4) Connect the other battery. Test.
I am not trying to say that all you need in your system is a capacitor. BUT, what I am trying to show here is that there is some benefit in some applications where an amplifier requires high current for quick impulse signals.
BTW... I totally agree that the best way to fix a voltage problem is an alt...
But capacitors still serve a purpose in a very few applications...
I agree 99.9% of the time people use Capacitors for the wrong reasons and don't really need them...
They are meant for 'stiffening' ie for short (VERY SHORT) impulse voltage drop issues.
Also, a battery only produces its own charge for a very short period. If batteries generated their own power by under going a great chemical reaction then we wouldn't need to charge them. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif
Go to this link...
http://falstad.com/circuit/
Import this data in the import menu under file.
$ 13 5.0E-6 30.96768661252054 30 5.0 50
v 64 320 64 192 0 0 40.0 14.0 0.0
r 144 144 144 224 0 5.1228
d 144 224 144 288 0
d 144 288 144 352 0
w 64 192 64 112 0
w 64 112 144 112 0
w 144 112 144 144 0
w 64 320 64 368 0
w 64 368 144 368 0
w 144 368 144 352 0
t 144 224 192 224 0 1 0.7888489281771617 0.7891001865734992
r 192 240 192 368 0 7.0E-4
w 144 368 192 368 0
p 192 112 192 208 0
w 192 208 224 208 0
w 224 208 224 368 0
w 224 368 256 368 0
c 336 144 336 272 0 100.0 13.993927120418611
c 480 144 480 272 0 1.0 13.997831899442744
r 560 144 560 272 0 0.05
r 336 272 336 288 0 0.0010
r 384 272 384 288 0 0.0010
r 480 272 480 288 0 1.0E-4
w 560 112 560 144 0
w 336 288 336 368 0
w 384 368 336 368 0
w 480 288 480 368 0
w 480 368 384 368 0
w 560 272 560 368 0
w 560 368 480 368 0
s 384 112 480 112 0 false false
s 336 112 384 112 0 false false
s 256 112 336 112 0 false false
s 336 144 336 112 0 true false
s 384 144 384 112 0 true false
s 480 144 480 112 0 true false
p 256 112 256 368 0
w 256 368 336 368 0
w 384 368 384 288 0
w 144 112 192 112 0
S 192 112 192 64 0 true false 0
r 208 64 256 64 0 0.0025
w 256 64 256 112 0
c 384 144 384 272 0 100.0 13.994026263554805
s 480 112 560 112 0 true true
o 0 64 0 2 20.0 1.6 0
o 17 64 0 2 20.0 9.765625E-5 1
o 17 64 0 1 10.0 9.765625E-5 1
o 43 64 0 2 20.0 9.765625E-5 2
o 43 64 0 1 10.0 9.765625E-5 2
o 18 64 0 2 20.0 9.765625E-5 3
o 18 64 0 1 10.0 9.765625E-5 3
o 32 64 0 1 7.62939453125E-5 9.765625E-5 4
o 19 64 0 2 7.62939453125E-5 9.765625E-5 5
o 19 64 0 1 7.62939453125E-5 9.765625E-5 5
o 36 64 0 2 20.0 9.765625E-5 6
Play with it a little bit. Especially with short impulses on the loads. (CLICK ON THE SWITCH TO CONNECT/DISCONNECT)
(BTW, these numbers are just set up to show my point and that is it.)
Basically... The current limiter circuit simulates a 250 Ampere alternator. The 100F Capacitors with the 1m Ohm resistors act like batteries (so to speak). The small capacitor acts like a normal capacitor with a much lower resistance and a quicker load reaction time than the battery.
Here are the steps to figuring out this stupid question.
1) Disconnect all the caps and batteries so you can only run on the alt. Click the load on and off several times and watch what happens to the voltage and the current.
-What you find is a instant voltage drop because of the load change and a pull of 250 ampere on the alt.
2)Connect only the capacitor. Test under load.
-What you will find is a slight 'stiffening' for short impulse loads. If you do this step correctly you will find that during short impulses the capacitor reacts to the change in load and the alt will not pull 250 amperes. However, if you leave it on long enough the capacitor will no longer be of no extra help.
3) Connect the one of the batteries. And test under load.
-You will find a much increased stability in the voltage. But, if you disconnect the capacitor you will find an increase in the current sent form the alternator.
4) Connect the other battery. Test.
I am not trying to say that all you need in your system is a capacitor. BUT, what I am trying to show here is that there is some benefit in some applications where an amplifier requires high current for quick impulse signals.
BTW... I totally agree that the best way to fix a voltage problem is an alt...
But capacitors still serve a purpose in a very few applications...
bdawson72
5,000+ posts
Finally Has Bass Again
**** I thought you were noah for a sec.
joetama
5,000+ posts
The British Ear
Oh no... That is my foot kicking NG... //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif
so ppl dont need 2 batteries so get a kinetik battery and be done with it close this thread LOL
helotaxi
5,000+ posts
Kilroy was Here
Problem with the above is that the ESR of most caps marketed for car audio use is way too high. The high ESR keeps the cap from delivering any substantial amount of current for any duration. The higher the current demand, the less voltage the cap delivers. Also, most batteries marketed for car audio use have very low ESRs. Actually low in the neighborhood of what the car audio caps have.
You should know as well as anyone that the battery doesn't make current but does store it in chemical form.
You should know as well as anyone that the battery doesn't make current but does store it in chemical form.
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