Capacitors and Batteries Needed?

[Databyter 10+ year member]

I'm going to be running an A/B 4 channel Amp (80 RMS) per @ 4 Ohms, also a D Class @ (300 RMS mono @ 4 Ohms). I'm thinking that I'll have alot of headroom with this setup and will not be running it near max power. ( Oh yea, and the 4 channel running 4 6 1/2" Alpine SPS 600's (80 watt RMS to 250 Peak), and a JL Woofer 300 Watt 10").

I'd like to run the system somewhat when the vehicle isn't running so I'm thinking maybe I'll need a deep cycle battery isolated from my Start batt?

Also would I need a Capacitor for this setup? How big?

I'm not going to be bumping Rap at high volume, but maybe rock, Reggae and Jazz at medium high volume. I want to be able to crank it up now and then when appropriate (time and place), but most of the time I just want it at a moderate volume but with a rich full range sound. I'm going to attempt to lower road noise and vibration so I don't have to compete with it..

Also If I get a deep cycle is it safe to have it in my passenger compartment, I don't have much room under the hood but alot more in my Subaru wagons passenger compartment or cargo area..

Someone mentioned an alternator as well, but I'm not looking to shake the street or anything, is that really necesary for a moderate SQ system, even with a deep cycle addon. It will only charge what I use, so I'm thinking I'm not going to be stressing it more for an extra batt.

Thoughts?

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[Twista89 10+ year member]

with that much power you wouldnt need to upgrade anything....

 

[n2audio 5,000+ posts]

Not a lot of power at all by today's standards. Don't bother with a cap.

At full volume with the engine off you're looking at a rough estimate of 23A of average current draw.

A quality starting battery should have a reserve capacity of around 100 min at 25A, some are closer to 150 min.

However, at the end of that time your battery would be near, possibly below 11v which 1) may or may not continue to operate your amps, and 2) may not be enough to crank the engine.

I would say with your unmodified electrical system you should get at least an hour of parking lot time at high volume. If it's not cranked - 1.5-2 hrs.

The 2nd battery would be a nice bit of insurance.

With the engine running you should be able to crank it indefinitely w/o any significant effect on the electrical system (unless you're driving with an unusually small electrical system).

 

[thericanballer 10+ year member]

dont get caps

 

[Databyter 10+ year member]

Thanks you guys. I wasn't thinking so (except for the extra batt which can't hurt on a Sunday afternoon at the island).

It's good to ask people who know stuff as opposed to those who think they know or are salespeople who may or may not know.

Your answers are very helpful and appreciated, thanks for taking the time.