install question

blndblu

First, let me say that I am not that familiar with car audio installation. With that being said, I just purchased 2 of the polk mono block amps to push to polk mm12's. I also have the polk 4 channel amp to push my highs. Highs are polk 6'1/2 component and polk 4*6 panels. I was told to run all three amps that I would need an aftermarket alternator and battery. Could someone here verify that for me, and if so possibly direct me in a good direction to receive a good price on these items.

exalted512

number one, you bought the wrong amps
you dont need the monoblock, you need the 2 channel (c300.2)
and if you have a small battery, you will need to get a bigger one
obviously the person you were talking to doesnt know much about car audio, because if he did he would know that no two cars are the same
not even a car thats the same make, model, and year...every single one is different
thats kind of borderline
you wont need a bigger alternator(unless the one you have SUCKS), but you might need to get dual batteries
id install the amps first, then see how much your voltage drops
but def. get a bigger battery if you have a small one now, you can pick up Energizer batteries for like $90 for 900CCA which is a great deal...its what i have in my truck...checn your local auto parts store
-Cody

[Deleted User]

A new alternator will do you more good than a new battery. Extra batteries actually can hurt your electrical system. The batteries main job is to start the car. Once the car is started, the alternator takes over supplying voltage to the car. When running, the alternator produces (on average) 13.6 volts. This is more than the battery which is 12 volts. If the alternator drops below 12 volts from amperage strain, then the car will get its power from the battery. If that happens, you definately need a high output alt. Multiple batteries put unneeded charging strain on the system. The only reason you would need this setup is if you're running the car stereo for long periods of time without the car running. Even then you should have a battery isolator. If you are doing a lot of shows, I would suggest investing in a 12 volt power supply.

LittleCar_w/12s

I guess if you have the room the two block's will be ok. Cody would know this: are those rated for 2ohm or 4? if they are rated for 2 ohm mono, then you are simply wasting money (only using half their power), but if they're matched to your 4ohm subs then you're ok, and will always have at least one running even if one dies.
As for batteries, I'd def go with an energizer for the price, or a yellow-top optima if you have money lying around (you get high CCA, hgh Capacity, and it's a deep-cycle)
As for alt, no need to replace that in most cases. especially if all you're running is regular sound, and not trying for high power SPL systems. Also replace your big three if only to make sure there's good connection (Battery to frame, engine to frame, and alt to battery)
-Jerry

bknauss

Errr, let's do a little math:
- Each 500.1 has 50A worth of fuses total (2 25A fuses)
- Each 300.2 has 60A worth of fuses total (2 30A fuses)

Let's start with the 300.2. Since the speakers you'll be using are 4 ohm, you'll never hit 60A of input current under normal conditions. The 60A of fuses are there for protection for the smaller load, which if you think of ohm's law (V=IR), then you know that sucks up the most current. So at RMS at 14.4V, you'll get an output of 300W total from all channels. Divide by 14.4V, that's 20.8A on the output. Assume that the amp is 60% efficient, that means the amp is sucking up about 35A. Not bad at all.

Now for the 500.1, once again, you won't be sucking up 50A worth of current since you're using a 4 ohm load. 350W RMS comes out assuming the 14.4V input. Using the same procedure for finding the current input (and now assuming an 80% efficiency), you find the current draw to be about 30A.

So now you've got 95A possibly being sucked up... but this is somewhat unrealistic since this is
a) assuming you're getting 14.4V from the battery and
b) RMS wattage is being output constantly. At least from what I've seen, its generally under this (although I could be totally wrong on that)
c) you're definitely not going to be powering the non-components with much less power than 75W. I don't even know if they handle that much at a constant rate.

Anyhoo, to get away from the math... I was running (at one point) the equivalent to 1 C300.2 and one C500.1. I never had a problem with dimming lights or anything, even at ear-bleed levels.


K-Nos

exalted512

if you get a battery isolator it will not put any extra load on your cars electrical system, what it does is charge one battery at a time
i believe your car is in fact a GM truck?
if so, i wouldnt even worry about getting a battery isolator, the alternator is strong enough to handle the load, just wire them in parallel
and lets put this into perspective...
$90 for a battery which will most likely be all you need...
OR
$500+ for a good alternator that WILL solve your problem but put you in a $500 hole and DECREASE performance of your truck(assuming you have a truck)
my vote goes to the battery
-Cody

MacLeod

I say just start out by buying a good strong battery like an Optima or Duralast and leaving it at that. If you dont have any voltage problems then I wouldnt worry about 2 batteries or upgraded alternators.

exalted512

Originally posted by MacLeod
I say just start out by buying a good strong battery like an Optima or Duralast and leaving it at that. If you dont have any voltage problems then I wouldnt worry about 2 batteries or upgraded alternators.

exactly
-Cody

LittleCar_w/12s

I third that