let it rip- Batt vs Cap discussion/debate...:hmmm:

Post by **mhyde71** » Tue Sep 21, 2010 8:10 pm

is this 100% or only in parts?
IDK for sure so i ask?

[youtube]http://www.youtube.com/watch?v=5Ckuc2df ... r_embedded[/youtube]

[youtube]http://www.youtube.com/watch?v=Yagui6O3 ... r_embedded[/youtube]

Post by **ttocs** » Tue Sep 21, 2010 8:37 pm

who is this asshat?

He is talking about a cap being a current storing device, is that a flux capacitor?

I can't go anymore past 6 mins....

Post by **mhyde71** » Tue Sep 21, 2010 8:39 pm

i couldnt watch much more either.

I heard and felt some shaky things being said and wondering..."W-w-w-wait what was that??"

Post by **ttocs** » Tue Sep 21, 2010 9:15 pm

besides the fact his stick figures have arms comming out of their heads it seems like he is just making it up as he goes.

brenzbmr@sb · Post by **brenzbmr@sb** » Tue Sep 21, 2010 10:27 pm

this guys is full of shit. the alternator is gonna stay at 14volts and battery is gonna stay at 12 volts

LOL......

ass hat it is

Post by **stipud** » Wed Sep 22, 2010 6:31 am

Well I watched the whole thing... he's got the gist of it at least. A lot of his specific examples weren't totally bang on, but it could be worse. I certainly wouldn't call him an asshat... it was definitely well intentioned.

shaheen · Post by **shaheen** » Wed Sep 22, 2010 6:32 am

Watched the first one and thought , WTF is he smoking......a cap ALWAYS discharges with bass notes, not only when the Alty cannot supply the current, does he not understand that the Alty's first job is to top up the battery and NOT support the electrical system of the car.

Post by **Eric D** » Wed Sep 22, 2010 6:42 am

I did not watch the clips (at work), but I will say this, based on what you guys are posting.

Current flows from higher voltage to lower voltage. So during normal usage of a stereo (at low output), the current being used by the amplifier is coming directly from the alternator (the highest source of voltage). Only when the current is great enough from the alternator to start dropping the voltage at the amplifier (due to the resistance of the wire) will the cap do anything. Up to this point the cap is just sitting there full of charge and doing nothing useful.

gbody805 · Post by **gbody805** » Wed Sep 22, 2010 7:05 am

shaheen wrote: does he not understand that the Alty's first job is to top up the battery and NOT support the electrical system of the car.

Your half right there.
The Altys job is to keep the battery at a state of ready but it then is called to support the entire electrical system so the battery is always at a state of ready.

Think of it this way.

You have a sealed glass with two straws. One straw goes to the water tap (Alt ) one straw to your mouth ( cars electrical draw )

As you turn on the tap (alt ) the water first fills the glass.
Once the glass is full does the water stop?
No. the water continuies to flow thru the full glass and out the second straw.

The battery it toped off and the car's system feeds off the over flow of current.

The Alt. has the ability to adjust it current to supply what it needed.
Driving in the day time to driving at night with lights on.
Driving in the morning and late afternon with A/C off then on.

As long as the Alt. Has the capacity to, one keep the battery topped off and still supply enough over flow to power the car.

Post by **stipud** » Wed Sep 22, 2010 7:12 am

Eric D wrote:Only when the current is great enough from the alternator to start dropping the voltage at the amplifier (due to the resistance of the wire) will the cap do anything. Up to this point the cap is just sitting there full of charge and doing nothing useful.

Nothing useful!? A/C ripple filter! That is the most important use for a capacitor if you ask me.

Post by **ttocs** » Wed Sep 22, 2010 7:17 am

and what does an ac ripple filter buy ya? I keep hearing it can help the SQ but never seen an a-b comparison where someone says it helps the sq.

This guy has no idea what the difference between voltage and current are. How can he explain how a cap works? He has a VERY general understanding if it, I would not be suprised if he learned it from reading wiki one er two times and thinking he got it.

Post by **Eric D** » Wed Sep 22, 2010 7:31 am

I agree with ttocs, what does the A/C ripple filter do to benefit anything? The battery already does a good job of that.

Plus, if an amplifier has a quality power supply, any benefit in filtration from an external cap will probably not be noticed. Car audio amps take the input current and chop it up thousands of times a second to then feed their transformer. The amp's own power supply filtration on the output of the power supply will probably all by eliminate the ripple at the power terminals.

Post by **ttocs** » Wed Sep 22, 2010 8:07 am

I am just not a fan of caps no matter big or small. Even the big ones seem to have their problems that would just not make it worth it to me.

Post by **stipud** » Wed Sep 22, 2010 8:24 am

I saw a visible difference in the ripple when measuring with my oscilloscope at the amps power terminals. Only about .1-.2v of ripple before, which became ruler flat afterwards. Of course the amp's internal capacitance is probably more than enough to reject this, but my system was all about having an absolutely overkill power distribution setup. I have a 200 amp externally regulated alternator, Optima BlueTop, 0 gauge and 1F capacitor only for a Ti500.4

Did I notice an audible difference when I added the cap? NOPE. Do I care? NOPE. It was all about having the best theoretical and measurable power distribution.

A cap could be used to help hold the system voltage higher, but only for insanely brief dips, and only a few amps of current. If you are seeing voltage drops of .5v or less, then it might work for you. Most people's setups with grossly overpowered bass amps and tiny stock alternators will not benefit from a capacitor, since it will be discharged in a few milliseconds and then become a draw as well. As a current storage device, batteries are a million times better.

So in general I would agree... caps aren't all that useful.

Post by **Eric D** » Wed Sep 22, 2010 10:46 am

A cap is not a draw. It only goes to what voltage potential it is fed, and only when there is "spare" charge to fill it.

If it were a draw, your battery would go dead in time and you would not be able to start the car (like leaving the car overnight for example).

gfunk_nz · Post by **gfunk_nz** » Wed Sep 22, 2010 11:48 am

wow I got to 2.30 and couldn't watch anymore, already he's proven himself to be quite a muppet, I'm betting it doesn't get any better . I suspect if I watched all of it I would feel a whole lot dumber

Post by **stipud** » Wed Sep 22, 2010 11:52 am

Eric D wrote:A cap is not a draw. It only goes to what voltage potential it is fed, and only when there is "spare" charge to fill it.

If it were a draw, your battery would go dead in time and you would not be able to start the car (like leaving the car overnight for example).

Take a discharged cap, hook it up to a battery and measure the current draw. While it's not a constant draw, it will draw power until it reaches balance with the system it is in. So we are just arguing semantics, since it only becomes a draw when the system voltage increases (which would mean you are no longer drawing too much amperage from your amplifier).

Post by **Eric D** » Wed Sep 22, 2010 2:48 pm

I guess my point is that the cap only stays at the voltage it is presented with. As you have stated, it reaches balance. If your alternator is at 14.4V, your amp is at 13V, and is drawing 50A of current, the cap wired near the amp will be at 13V as well, and will be drawing 0A of current.

I often see people post ideas that once the cap is drained, it then "robs" your amp of power it could be getting, and that is simply not true.

Post by **fuzzysnuggleduck** » Wed Sep 22, 2010 3:03 pm

Eric D wrote:I often see people post ideas that once the cap is drained, it then "robs" your amp of power it could be getting, and that is simply not true.

So if you've got the bass boost knob cranked and some phat bass hammering the crap out of your charging system due to the massive amount of current your bass amp is pulling, the cap discharges nearly immediately but then remains discharged until your amp is no longer drawing ALL the available current out of the alt/battery?

Is that correct or am I misunderstanding?

Post by **Eric D** » Wed Sep 22, 2010 3:06 pm

OK, I just watched both videos. The first video is somewhat reasonable, the second is mostly BS.

Overall, his analogy is pretty lame.

Post by **Eric D** » Wed Sep 22, 2010 3:13 pm

fuzzysnuggleduck wrote:
Eric D wrote:I often see people post ideas that once the cap is drained, it then "robs" your amp of power it could be getting, and that is simply not true.
So if you've got the bass boost knob cranked and some phat bass hammering the crap out of your charging system due to the massive amount of current your bass amp is pulling, the cap discharges nearly immediately but then remains discharged until your amp is no longer drawing ALL the available current out of the alt/battery?

Is that correct or am I misunderstanding?

That sounds 100% correct to me.

The whole reason a cap does anything at all is because our power wire has resistance. If we ran a 0ga wire, which was frozen to become a superconductor, the cap would become totally useless as any voltage at the alternator would be presented with no loss to the amp.

In my example above where the amp was getting 13V while drawing 50A of current, the system would be "steady state" at that point. If you removed the cap while it was playing, the cap would stay at 13V outside of the system. Then if you put it back there would be no spark, as it would be at the same voltage that point in the wiring is at. Now, if you removed the cap, then discharged it fully back down to 0V, and put it back in the system, it would draw a ton of current very fast to fill it back up to 13V. Once at 13V it would cease to draw any current.

Post by **Eric D** » Wed Sep 22, 2010 3:30 pm

Here is my half assed attempt at an analogy for this...

Imagine a river. The river starts at a spring coming from the ground. The river then flows into a lake. The river flows out of the lake, and then to the ocean.

The spring would be an alternator.
The lake a capacitor.
The ocean is your amplifier.

If the ocean somehow demands more water (maybe sea level goes down from evaporation for example), the lake starts to drain. It still has water flowing into it, but more is going out, so the lake is slowly depleted. When the lake is empty, water just flows right on through it, and the ocean looses the additional flow the lake was adding. If the ocean still demands more, the flow ahead of and behind the lake is reduced even more. The lake is not trying to fill up, the water just flows into it, and back out of it, with little to no resistance. Only when the ocean no longer demands as much flow will the water start to back up into the lake again and fill it. Depending on when the ocean needs water again, the lake may never fill.

Now, what is a battery? It would be a big ass lake, like Lake Michigan, or Lake Superior for example. The same things are happening to it, but it is just much less noticeable.

Now, obviously there are some holes in my example, but it is the best I can do off the top of my head.

Post by **ttocs** » Wed Sep 22, 2010 3:43 pm

oh man the 2nd was worse then the first?

Post by **Eric D** » Wed Sep 22, 2010 3:55 pm

Far worse...

Post by **ttocs** » Wed Sep 22, 2010 4:08 pm

jesus I felt 2 iq points dumber and had a head ache from the first.

I often wonder at what point these people that decide to do this crap. At what point does he deciede that he knows enough that he should be making instructional videos to help others? I mean he has done some reading but is still not quite to the point that he should be teaching....