S-10 Forum banner
Cancel

Capacitors: What You Need To Know Before Buying.

24591 Views 59 Replies 24 Participants Last post by  Christianbazin, 
old_skool_noma
So, you just installed your new stereo, but you notice your lights dim when the bass hits?

Or

You're buying parts to build a system and youre worried that your lights will dim because (insert name here) said that you need one?

If you answered yes to either of these questions, a capacitor is not the answer to your problems.

A capacitor acts like a small battery to filter small ripples in your electrical system, it discharges when the input voltage drops below the charged level of the capacitor to keep a constant voltage.

Now you're probably wondering why they wont fix your problem if they do what I just said, right?

Well, here is your answer, a capacitor simply will not support any electrical components placing that much demand on your electrical system. Sure you could get a huge capacitor. The price of one of a capacitor large enough to adequately support that substantial of an electrical system just isn't worth the difference, and you're still not fixing your underlying problem, an inadequate charging system. Once the capacitor is discharged from being over extended from being used improperly, it becomes even more of a strain on your already limping electrical system by trying to recharge.

Now you ask, if a capacitor wont fix my problem, then what will?

Well, there are three steps that you can do to combat your inadequate charging system. Steps 2 and 3 are interchangeable, I would recommend them in the listed order, but it isn't as important as the first.


Step one: upgrade your big three wiring, these wires are:
1. Alternator to Battery (+)
2. Frame to Battery(-)
3. Engine to Frame or Battery (-)

See the following link for more detail.
Big Three Upgrade: How To


Step Two: Higher Output Alternator.
Simply replace your factory alternator with an alternator that put out more amperage. The most common and cost effective is the AD244 from the newer full size trucks.

See the following link for more information about the swap.
AD244 Upgrade: How To


Step Three: Add Another Battery
Just like it says, add another battery, you should use at least the same size wire that you used for your big three, if you have any considerable length of wire to reach the new battery, you need to fuse the wire at each end to help prevent any electrical fires if the insulation should become compromised.

If you are dealing with batteries of different types and or ages, an isolator should also be used to prevent premature battery failure, but this will also cause a half volt drop across the isolator.


This should fix your problems for up to a moderately high powered system (2000-4000 RMS Watts) if it doesn't repeat steps 2 and 3 and necessary.

Now that you've read why you don't need a capacitor, now you can see what they are useful for.
You already know that capacitors filter ripples in your electrical current from the beginning of this tutorial.
There are sound quality benefits to using capacitors as a filter before your amps. The first benefit is if there is an immediate need for a high current draw such as a bass note with a very fast attack, the capacitor can discharge faster to supply the required current, in addition to the current that is already there from your battery and alternator to keep your amplifiers response as fast as it can be.
Secondly it helps keep voltage spikes from reaching your amplifiers.

In conclusion, unless you have extremely fine tuned hearing chances are, you will never miss a capacitor in your system, but, I will not discourage you from getting one, so long as you are using it for the right reasons, if you are trying to fix a voltage problem with it, you are simply trying to put a band aid on a bullet wound, but if you have a strong electrical system and are looking for something to smooth peaks and provide an additional kick if its needed, chances are a capacitor is what you are looking for.


Happy Building,
Brandon
See less See more
Reply
Save
Like
1 - 20 of 60 Posts
eriley
Sticky...

This is perfect, you should only ever use a capacitor to smooth out your bass response, for everything else its just a band-aid.
Reply
Save
Like
Speedy2222
they said on xtreme 4x4 yesterday that they're used to stop headlights from dimming =-o i sent them an email setting them straight...
Reply
Save
Like
old_skool_noma
T hate it when TV shows especially give wrong information like that, its mainly just a marketing tool to sell something cheap to manufacture, I would think that the sales stated out using them as I described that they should be, then someone used it for a band aid and it made their dimming less noticeable so they thought it was the cure, so the lower end companies caught wind of this and exploited a lot of sales from people that didn't know any better
Reply
Save
Like
B_Rich
Very well written old skool noma. I think you'll really reach out to people who are debating this very topic, without sounding like an asshole and making them feel like shit. I hate doing that to people.

I like the "repeat steps 2 and 3 as necessary" part :haha:
Reply
Save
Like
Deja_Vu969
Wow...that goes pretty in depth. I don't have anything big enough to drain my system...yet. But that explains a lot more than most threads on here. (that I've read). Thanks
Reply
Save
Like
bubbagt57
STICKY perfectly done thanks
Reply
Save
Like
T
Very good write-up :)

I wish someone would do one on making a bracket for 2-3 alts retaining a/c. There is one good thread on here about it, but he didnt show a very good shot of the bracket, and Im scared Id mess it up.
Reply
Save
Like
beandip
Great write up, should be a sticky.
Reply
Save
Like
B_Rich
therule546 said:
Im scared Id mess it up.
Click to expand...
Don't take this the wrong way, but you'll never get anything accomplished in life if you have that attitude toward life.

Just take it slow, think things through, ask yourself what could go wrong, then despite whatever you're thinking now, just go for it.

/thread hijack.
Reply
Save
Like
M
A capacitor is like a battery in that it stores a charge, but (for the size) charge and discharge much faster, and stores less. A large capacitor near amp may help with short current surges (thumping bass) with under sized or improper wiring, but common sizes for capacitors would not help much for more sustained current surges (long bass note).

The longer the wire and smaller the conductor within, the more resistance to the current flow. With heavy current draw the voltage from the battery at the other end of the wire drops. If your connecting a heavy load to fuse block/alternator and the cab/frame, it's at the wrong end of the stock wiring that already has it's load to deal with.

Wire up directly (with fuse) to the battery, or at least to the where the heavy cables end at the starter solenoid and engine block. Wiring up to a second battery does essentially the same thing (directly to the battery), but it is also similar to having a super sized capacitor (and more wire) in between the amplifier and the rest of your electrical system. For moderate power a second battery not really needed. Then if your lights slowly dim down while your running down the road with the stereo cranked, you need higher output alternator, and heavier wiring between it and the battery (or starter solenoid) and well grounded (the case/mounting). For better performance of sound system use a heavier gauge wire. Second battery is sometime also used so you don't discharge the main battery (for starting) while parked by having the second switched out of the electrical system when the engine is not running.

Since audio system draws a surging high current instead of constant, you can actually get away with much smaller then ideal conductor sizes without burning up the wires. That's the same reason (and cost) that battery and jumper cables are not commonly 1/2 inch thick or more of copper conductor.

For reference here is some common constant current ratings (rubber insulation), wire conductor gauge/amps:
14g/15a, 12g/20a, 10g/25a, 8g/35a, 6g/50a, 4g/70a, 2g/90a, 1g/100a, 0g/125a, 00g/150, 000g/175a, 0000g/225a
Yes wire gauge number decreases for larger conductor, more amperage, and less resistance. 1gauge is just over 1/4 inch diameter conductor and 0000 gauge is almost 1/2 inch.
See less See more
Reply
Save
Like
old_skool_noma
Thank you to whoever stickied this
Reply
Save
Like
M
Forgot to mention using relay for switching power if you connect stuff that don't shut off by it self. Most large amps have a relay built in hence the 2 positive wires, 1 gets connected to low current switched circuit. Also over fusing risks burning/melting wires if they get shorted, lower slow blow fuse or circuit breaker is better.
Reply
Save
Like
B_Rich
max1million said:
Forgot to mention using relay for switching power if you connect stuff that don't shut off by it self. Most large amps have a relay built in hence the 2 positive wires, 1 gets connected to low current switched circuit. Also over fusing risks burning/melting wires if they get shorted, lower slow blow fuse or circuit breaker is better.
Click to expand...
I hate to burst your bubble, but those are 2 things that 99.99% of car audio installs consist of. A remote wire on the amp and a fused power wire.

I've never seen an amp that doesn't have a remote wire input on it....
Reply
Save
Like
M
bubble, you missed the first sentence and misinterpreted the rest

"...stuff that don't shut off by it self..." or include relay as most amps by example do (you missed those that didn't)

and while (going back to other reply) you can run an audio amp on less then ideal wire gauge, by over fusing (or none) a smaller wire the risk of melting it in unintentional short circuit or other over current condition is greater, and a more reasonable slow blow or breaker may be better in that situation.

hope that clears it up for you
Reply
Save
Like
old_skool_noma
max1million said:
Forgot to mention using relay for switching power if you connect stuff that don't shut off by it self. Most large amps have a relay built in hence the 2 positive wires, 1 gets connected to low current switched circuit. Also over fusing risks burning/melting wires if they get shorted, lower slow blow fuse or circuit breaker is better.
Click to expand...
the reason i said 2 fuses is because if you have a battery in the bed, you need to prevent the wire between the batteries fused at both ends to prevent current from entering the wire from both sides if the insulation is comprised, yes a circuit breaker will work in this situation, but they can trip from vibrations where as a fuse will not
Reply
Save
Like
B_Rich
old_skool_noma said:
the reason i said 2 fuses is because if you have a battery in the bed, you need to prevent the wire between the batteries fused at both ends to prevent current from entering the wire from both sides if the insulation is comprised, yes a circuit breaker will work in this situation, but they can trip from vibrations where as a fuse will not
Click to expand...
I should whip out my super-dee-dooper-awersome drawing :haha: :rotf:
Reply
Save
Like
old_skool_noma
VoRtEcZr243 said:
I should whip out my super-dee-dooper-awersome drawing :haha: :rotf:
Click to expand...
be my guest
Reply
Save
Like
M
I apologize for not making abundantly clear in reply #13 that it was a continuation of reply #11, and for the confusion over it's wording. Reply #13 should start:
"I forgot to mention in reply #11 and the following is in reference to it"
I would have preferred being able to edit directly into reply #11 versus a separate reply, while also using the later improved wording.

I suspect that in reply #16 you are refering to "over fusing" as well as the use of a circuit breaker, in reply #13. If so by "over fusing" I refer to using a fuse of higher amperage rating then is recommended. And breakers often slower to react can allow surges while still limiting the average current, thus better then "over fusing" and similar to using a slow blow fuse. I would however agree, reply #16, more protection where needed is better. With that the current ratings in reply #11, for those that would like to know some recommended values, are from a reference which I use.

My only real contradiction of the original post is: There is no need upgrade the stock small wiring when it is just as easy to go to the source (the battery) or at least to the where the heavy gauge wires (cables) that can handle the current end, when either method will generally do.

If however you are upgrading to a 200amp alternator then go ahead and put in 0000 gauge wire or double up on 1 gauge, it should only help. And if you prefer to change "your big three wiring" as per the original post and it's reference, you might also consider same for frame (or engine block or battery - ) to cab body, if intending to use it for a negative connection (grounding point) for everything.

Again I apologize, for any confusion over my input. Would you please point that thing somewhere else.
See less See more
Reply
Save
Like
eriley
max what in the **** are you talking about jesus christ i can't understand a thing you are saying.

The only thing I took out of that is you saying you don't need to upgrade the stock small wiring when you can just go to the source (the battery). Which doesn't make any sense, since the source is the alternator. Therefore by upgrading the stock small wiring you are going straight to the source.
Reply
Save
Like
1 - 20 of 60 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
S-10 Forum
S10forum is the community to discuss the S-Series, Chevrolet Colorado and GMC Canyon. Join to discuss rebuilds, modifications, tech articles and more!
Full Forum Listing
Explore Our Forums
Member Projects 262ci Forum (4.3) Member Rides Exterior / Paint 2.2L - 2nd gen 4-banging
Top