Everyone has opinions on caps. This is mine I say go for a cap because the cap is capable of charging and releasing energy much faster than the battery can.
The cap will keep up with the demands of the amps better once the car is started.
One farad of capacitance for each 1000 watts.

The two extra batterys are only gonna help for engine off listening time. Any other time they are just gonna be an extra load on the alternator. Electricity takes the path of least resistance. Why make any thing work harder than it has too.

I would most definatly upgrade the alternator, and most important make sure to use the biggest size cable you can. That much power I would go with 1/0 gauge cable. And make sure you have good chassis grounds.

I may get flamed for this but it is my .02

Tim

Charging a dual battery setup will have no ill effects on the alternator, so long as an isolator is installed as well.

I straddle the fence on the cap issue. It doesn't hurt having it in there, and it does help when the low-notes hit to an extent. I ran one when I ran a HiFonics Samson X and some sub that totally escapes my mind (it was American made though), and I noticed some improvement.

Hope this helps:

http://www.caraudiocentral.net/forum...ead.php?t=1888

Make the bass hit harder. No

Help keep the votage up. Yes
That is what a capacitor does, it stores and releases energy really quickly when your amps need it most.

Tim

I couldn't find this the other day when I was searching, but this was a test done by a an audio tech.



This is a real world test that was measured by Richard Clark on a Audio Precision unit to portray what happens with a typical capacitor install.
The main point for those who point out the obvious differences between the Red (cap installed) and yellow (cap not installed)…how much of a dB difference is .1-.4 volts in terms of music? And do you feel you are going to hear this within a car? On with the explaination:

Dark Blue curve---
For our first test we played the system with the engine off and no cap. The result was the purple trace at the bottom. We played the system as loud as we could get it that seemed to produce no audible distortion. This was track 30 of the IASCA disc. It starts off with fairly low level sounds for the first 34 seconds. In order to insure the electrical system was stable we did not start the measurement until we were 20 seconds into the song. This means that our 0 starting point is :20 on the CD counter.
The battery was able to maintain it'* voltage just below 12.5 until the loud bass hits at 34 seconds (14 seconds into our chart) At this time it dropped to about 11.5 and had a few large variations due to the music. According to the computer calculations (third chart) the average voltage for this test was 11.7volts. This test was done as a baseline for the following tests.

Yellow curve—no cap
For this test the volume was left as it was for the baseline test. The engine was started. Notice that at low volume the alternator was able to maintain about 14 volts. When the loud music hit the voltage dropped to about 12.5 where it remained
except for a few short moments where it actually climbed back to over 13.5 volts. The computer averaged calculations for the average voltage during the 100 seconds of this test was 12.973 volts.

Red curve—cap added
This test was identical to the previous test except the cap (15 farad type) was added 6 inches from the amp with 4 gauge wire—no relays or fuses. The red curve seems to overlay the yellow except that the actual peaks don’t rise as fast or as high during the brief quiet moments. I feel this would be due to the alternator having to recharge the cap. The voltage on loud passages hovered around 12.5 volts. The computer averaged calculations for this test show the average voltage to be 12.878 volts. I see no meaningful differences with or without the cap. I certainly don’t see the voltage sitting solid at 14 volts. One note I might add is that this was a two thousand watt system driven right to clipping and the average voltage stayed above 12.8 with a stock 80 amp alternator. Under these conditions the battery would never discharge! The green and light blue curves were done just for kicks while we had the system set up. In both these tests we turned the volume up until the system was very distorted. This placed a severe load on the alternator and caused the voltage to dip as low as 12 volts. The curves seem to follow each other so closely that unless you have a good monitor it is doubtful you can tell there are two curves. The average voltage for these two curves were both 12.277 and 12.295 volts. If this volume were sustained for very long periods of time this battery would discharge

15 farad is an excessive amount of capacitance for that system, im suprised to see little to no difference.

but speaking from experiance, and also stated before. with my 2000 watts rms system, i noticed no difference in the voltage drops (lights dimming) when i added a cap, then a battery in the trunk, and then another cap. this totals 3 farads of capacitance and a yellow top in the trunk. and the voltage on the cap displayed about the same results as that test. mid 12v on hard bass.

i did however notice a difference in the light dimming with the upgrade of an alternater. i only went from the 105 to a 140, (which is still not enough amps) but the cap would be at low 13v and sometimes high 12v (12.9ish).

Such low amount of a capacitor, for example 1 farad, will not be enough to properly keep a systems voltage up.

If anything, a capacitor is a crutch, or a bandaid, for an electrical system in need of an upgrade.

If you want to do yourself some good, do as did and upgrade the alternator and battery. While your at it, BE SURE to upgrade your alternator and battery cables as well (all grounds and power cable'*).

literally LOL, ha ha ha,


yeah, what he said

I would use dual alts if possible and go for a charging capacity of 280+ amps my .02
a lot bigger difference than a cap.