dual batteries or use a cap?

[punch]

will have 1400watts at some point in time, should i go with dual batteries, or just cheap out and use a cap?

[BailOut]

Using a capacitor isn't about "cheaping out", but eliminating the weight and space requirements of extra batteries. Once powered up they also deliver high loads much faster than you can draw it from a deep cycle battery, and trickle charge in between spikes.

Your 12V system and equipment will thank you for it.

[Black Yaris]

as BailOut said caps are the far superior way to go... with only 1400 watts a small caps should do a 1 farad capacitor should do ya... 1400 watts will not push it too much at all

[punch]

thanks, I was reading on the audio forums, caps suck.... you get more power from a 9volt battery etc.... a cap is by far an easier route to go, and I may try just that, and if I need more can upgrade later...

[Razr]

1. Are you talking RMS power?

2. Do you listen to music that contains continuous, or near-continuous bass?

If you answered yes to #1 and #2, here's a basic rundown of how much juice it'll need:

Class B: 1400W @ ~60% effeciency = 1960W draw / 12.5v = 156.8 Amps.

Class D: 1400W @ ~90% effeciency = 1540W draw / 12.5v = 123 Amps.

The best/biggest battery you could fit under the hood in a Yaris will at best do 80A continuous, most typical batteries will do 40-60A continous. Forget about the CCA (Cold Cranking Amps) rating, that has nothing to do with continuous power delivery - the spec you need to look into is: Ah (Amp Hours).

So if your going to be ground-pounding with this amp, I'd seriously suggest a 2nd battery rated at 80Ah or more. There's no way a cap will cut it.

[jdium]

Caps are a band-aid, only cover up a problem. Fix the problem. Dual batteries are worthless unless you can keep them charged. It comes down to the alternator and your wiring being up to snuff...if you are really trying to do it right, custom alt and wire is the only way, cap just covers up the fact that your alt isn't keeping up...

My .02

[punch]

yeah, the wiring will be done right, but who makes an aftermarket alternator for our tiny cars?????

[jdium]

Originally Posted by punch

yeah, the wiring will be done right, but who makes an aftermarket alternator for our tiny cars?????

Nobody that I know of

There might be the possibility of finding someone with the ability to do a custom re-wind to increase the output...

[Razr]

Originally Posted by punch

yeah, the wiring will be done right, but who makes an aftermarket alternator for our tiny cars?????

There's a buch of aftermarket alternators out there with various fitments so I'm sure there has to be at least one that'll fit Yarii. Try looking at the usual accessory suspsects like Stinger/AAMP, Streetwires, Monster etc or just google for car audio alternators - plenty of hits.

That said, whether or not you'll need a beefy alternator all comes down to the way you use the system - if your pounding it from ignition to stop then yeah, you'll need a big alternator. But if you're system gets anough of a break between sessions the stock alternator might be able to recharge both batteries sufficiently. Of course the cheaper route if you're not driving the car all the time is to use a mains battery charger to top the batteries up while parked.

While on the subject, I'd like to put my $.02 in on caps - IMHO they're not at all useless nor a even band-aid. The fact is that due to the higher internal resistance in a battery, they just can't deliver big, instantaneous peaks of current like a cap can. Even with fully charged dual batteries (which effectively lowers the resistance) you can still get voltage drops on the big bass hits, which means less power output from your system.

Caps do help in these situations, but their importance shouldn't be overstated either, as they can *only* help in these situations. A good rule of thumb is when you see disco lights (i.e. your lights start dimming on bass hits) a cap is probably a good idea.

[jdium]

Caps are great if you can fill them quick enough. What happens when that first bass 'hit' comes, empties your cap, then comes again before it's full? Then you are drawing directly off the battery, which as stated, has a lot slower dispersion rate. From there, until your music slows, it's a game of duck duck goose, chasing the weakest link in a circle...

If you listen to music that barely draws on your sub, caps are a good thing. If you are out for that one big SPL hit, a monster farad cap is the solution, but for daily drive deep rolling music, a cap is only good for the 1st big hit, then just becomes another draw on the alternator...the alternator is usually the goose if you think you need a cap...

[punch]

ok guys, i've decided to go with a kinetic battery in the trunk ( I have a sedan) to help with the amps...

I'm still looking for an HO alternator...

[bigsky2]

Originally Posted by jdium

Caps are a band-aid, only cover up a problem. Fix the problem. Dual batteries are worthless unless you can keep them charged. It comes down to the alternator and your wiring being up to snuff...if you are really trying to do it right, custom alt and wire is the only way, cap just covers up the fact that your alt isn't keeping up...

My .02

QFT

[jdium]

Originally Posted by bigsky2

QFT

HUH

[bigsky2]

Originally Posted by jdium

HUH

QFT = Quoted for Truth



Your post is bang on; a cap is only a short term solution. As an extra electrical component, it draws additional power from an already limited alternator.

[jdium]

Originally Posted by bigsky2

QFT = Quoted for Truth



Your post is bang on; a cap is only a short term solution. As an extra electrical component, it draws additional power from an already limited alternator.

AGY

Ahh, Got Ya