Why does everyone hate capacitors?

[CBFryman2 5,000+ posts]

Hypothetically...jebus. //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

Nothing wrong with walmart batteries. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[prochobo 10+ year member]

You will see more real benefit from doing the Big 3 and you neither want nor need a cap in your situation.
In most cases with a daily driver system, any current shortfall is a transient one. Without some kind of buffer on the alt, adding a bigger alt by itself isn't going to stop transient current shortfalls or the quick voltage dips that go along with them. The battery is that buffer. The power output of the alt is dependant on RPM and demand. The output of the battery is totally dependant on demand. The alt has a short delay in response to an increase in demand the battery doesn't. Also depending on the amp it is quite possible to pull a current transient that the alt has no chance of supporting. Without a good battery to pick up the slack you're in the same boat as when you didn't have an upgraded alt.

THANK YOU for clearing that up! There are SO many people that think the first/second step is an upgraded alt, but in reality, it doesn't matter. Maybe people will stop shooting shit out of their ***** now because I hate seeing false information passed on to the masses. Just to prove you don't need an upgraded alt:

I have a 90 amp alt and a YT under the hood. Big 3 of course and 1/0 wire. Amp is an MA HK4000D being ran at .75ohms. Now, with a daily system playing music, you won't get nearly as much current draw as straight tones. I can drive around and crank the volume high with no problems and I've been doing so for the past 9 months with at least 3kw+ amps. With the YT, I can maintain my steady 12v, but with the stock battery, it can easily turn into a low 10v.

"But since you have a big amp that draws so much amperage and a puny alt, doesn't that mean your battery will eventually die?"

Do you listen to straight tones 24/7? Music is dynamic and between the bass hits, the battery will recharge. Been doing for a long time and never had a problem starting.

Let's turn this to the flipside (say I did what most people say others "should" do). Instead of getting a YT, I decided to get a 200 amp alt keeping my stock battery. 200 amps is no where near enough current to fully power my amp or any of my previous amps. So how does the amp get enough amperage if the alt cannot supply enough current? It draws the rest of the power from the battery as helotaxi said. After the amp draws the full 200 amps from the alt, it's going to draw the additional (150ish) amps from the stock battery, which is probably old and worn out, and will probably not have enough juice to keep up with the added current draw for extended amounts of time or daily driving in general.

Here's another example: snoop d-o-double-jizzle (snoopdan haha). I know he had his stock 90amp (I believe) alt for most of the season and daily drove with his Adassa for sometime. What powered it? The batteries! I'm just trying to show that you can go either way and more than likely, either way would work, it just depends on how much you wanna spend.

Keep in mind, I am talking about BIG amps here. If the OP is talking about some 1.5-2kw amp, do the Big 3, get a battery, and call it a day.

 

[helotaxi 5,000+ posts]

Keep in mind, I am talking about BIG amps here. If the OP is talking about some 1.5-2kw amp, do the Big 3, get a battery, and call it a day.

Far as I'm concerned 1.5-2kW is a BIG amp...but I don't do SPL.

 

[prochobo 10+ year member]

Far as I'm concerned 1.5-2kW is a BIG amp...but I don't do SPL.

Yeah, just different perspectives I guess. I said 1.5-2kw because I've had no problems powering one with a stock alt/upgraded battery and if the OP's got a bigger alt than me, he oughta be just fine.

 

[PV Audio 5,000+ posts]

2kw is a huge amp for daily. If you're doing this for competing, then you would have already known the answer to your own question. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[yischrax 10+ year member]

I look at this like getting dressed I don't walk out of my house with just my boxers and shoes I put all my clothes on to be presentable. If your going to build a system droping a few 1000 into it and spend couple 100 on deadening or so and couple 100 on your remote start and a alrm spend what is needed get new battery and or extra battery bigger alt and upgrade magic 3 do it all to do it right you need all 3 hand in hand to work well. Just like building a engine you can skimp on a few parts replacing them but running a stock fuel pump on a built engine isn't very smart just like stock intake on built engine or stock plugs and wires why not pay the little more and get what you can out of it upgrading to what is needed.

 

[iceteebone 5,000+ posts]

i never knew a constant 12 volt was a good thing since your electrical system should be atleast 13.8 volts

 

[Thnking 10+ year member]

The reasoning for voltage dropping (when the load isn't exceeding the alternator's output) is because of the cycling of the stator's field.

It's not because the alternator isn't "fast" enough to react to changes in load. It's because the current field isn't strong enough at X RPM's. Increase the size of the alternator, reduce the voltage drops.

Capacitors dissipate a lot of energy. 1/2 of the energy is dissipated during charging, 1/2 of the energy is dissipated during the discharge. That alone in itself makes a capacitor not worth owning for helping to "smooth" out the DC.

 

[CBFryman2 5,000+ posts]

Double Post.

 

[CBFryman2 5,000+ posts]

The reasoning for voltage dropping (when the load isn't exceeding the alternator's output) is because of the cycling of the stator's field.
It's not because the alternator isn't "fast" enough to react to changes in load. It's because the current field isn't strong enough at X RPM's. Increase the size of the alternator, reduce the voltage drops.

Capacitors dissipate a lot of energy. 1/2 of the energy is dissipated during charging, 1/2 of the energy is dissipated during the discharge. That alone in itself makes a capacitor not worth owning for helping to "smooth" out the DC.

Alternators are load dependant. If you have a 300a alt and you only need 30a to run down the road with a charged battery the alt is only going to produce 30a. If the system hits the alternator has to sence the voltage drop and increase the strength of the electromagnetic feild. This can happen in a very short ammount of time but the delay is still enough to see a small flicker in the head lights. Batterys can only put out at the voltage they are charged to and not as high a voltage as the alternator can put out. A cap will charge to what ever voltage it is given (assumeing you dont exceed it's voltage, then it goes boom like so) this keeps the alternator output voltage at a constant when you have the capacitance to do so.

 

[thylantyr 10+ year member]

The problem with capacitor threads is the answer to the question is a variable.

The three most common symptoms or concerns are;

1. Headlight dimming

2. Amplifier power issues

3. SQ

Capacitor threads fail because;

1. People lump all the symptoms or concerns into one bag and generalize.

2. Every install is different, what works for you may not work for another, visa versa.

3. Many times people don't know how to install the capacitor properly to address a specific concern, so if it didn't work for them, it doesn't work for everyone and visa versa.

4. People don't take measurements or do AB/X testing to see if the improvement exists if the issue is amplifier performance related.

I can argue for and against the use of capacitors, it just depends on what problem needs solving.

 

[CBFryman2 5,000+ posts]

The problem with capacitor threads is the answer to the question is a variable.
The three most common symptoms or concerns are;

1. Headlight dimming

2. Amplifier power issues

3. SQ

Capacitor threads fail because;

1. People lump all the symptoms or concerns into one bag and generalize.

2. Every install is different, what works for you may not work for another, visa versa.

3. Many times people don't know how to install the capacitor properly to address a specific concern, so if it didn't work for them, it doesn't work for everyone and visa versa.

4. People don't take measurements or do AB/X testing to see if the improvement exists if the issue is amplifier performance related.

I can argue for and against the use of capacitors, it just depends on what problem needs solving.

Looks back on page 2...

 

[Thnking 10+ year member]

Alternators are load dependant. If you have a 300a alt and you only need 30a to run down the road with a charged battery the alt is only going to produce 30a. If the system hits the alternator has to sence the voltage drop and increase the strength of the electromagnetic feild. This can happen in a very short ammount of time but the delay is still enough to see a small flicker in the head lights. Batterys can only put out at the voltage they are charged to and not as high a voltage as the alternator can put out. A cap will charge to what ever voltage it is given (assumeing you dont exceed it's voltage, then it goes boom like so) this keeps the alternator output voltage at a constant when you have the capacitance to do so.

You're a little confused on the electromagnetic operation.

It's obvious that the regulator adjusts voltage based on the field. If the alternator is transferring (I) current at (V) voltage and a load changes, the regulator adjusts the field density. There are 4 main sources of a voltage drop;

1. Diode Vdrop

2. Regulator Vlimiting to maintain current.

3. Circuit lumped resistance

4. Mechanical to electrical transference (and associated time)

Voltage drop in the circuit (again assuming load doesn't >= alternator's max output) is mainly caused by the diode Vdrop, and the associated regulators reaction to this Vdrop. This is a RELATIVE change in energy desnity to meet load (based on the circuit's loss design). With a 300A alternator and a 30A load the relative field density is low....ie low Vdrop.

With a 70A alternator and a 30A load, the relative field density is much higher.

 

[Thnking 10+ year member]

A cap will charge to what ever voltage it is given (assumeing you dont exceed it's voltage, then it goes boom like so) this keeps the alternator output voltage at a constant when you have the capacitance to do so.

A capacitor will charge to its capacitance value and while it's doing so, 1/2 of the energy will be dissipated as heat. And while it's discharging, 1/2 of the energy will be dissipated as heat. It's the law on conservation.

And typical caps have very low relative energy storage capacity.

 

[CBFryman2 5,000+ posts]

Still not what I'm talking about but ok.

Guys with huge alternators and big battery banks still have voltage flicker when the amps suddenly draw gobs of current. If the alternator is enough to handle the current the lights will usually return back to normal.