Can I get by with stock?

[Wehan]

My car is a 2007 Chevy cobalt, has a 115 alternator and 2ga running from alt to battery. I don't have anything installed yet but I have a Rockford t1000-4ad and a t1500.1bdcp. the 4ch will be running 4 100w rms speakers and the subs are fully loaded FI SSD 12's. I really only plan on having the car another year or 2 so I hate the idea of plunking $4-500 into an alternator but if I must than I must. If I drop in another battery like a juicebox grape and watch my voltage when I'm really cranking it will I be OK or am I just asking for trouble?

[Broke_Audio_Addict]

You're gonna need the alt.

[Wehan]

Do you think a 140A idle 220A peak from Singer will get it done?

[Broke_Audio_Addict]

200 amps or close at idle would be what I'd want with that setup.

[everybodyknowme]

yes 200 amps idle is best but I think you can make it with 140 idle and a back battery.

If you're really going to ditch the car in a year or 2 I just don't think its financially smart to invest in an alt that big just to lose out when you get rid of it. I think you would have trouble trying to sell the alt as there's not too many cobalt's anymore. But if you have the funds go ahead.

Personally I would look at a local rewound. I normally do recommend this but since you said the car will be ditch soon this makes an exception. And I would add that second battery and watch the meter.

[Wehan]

200 amps or close at idle would be what I'd want with that setup.

Considering I pretty much never bump at idle (no stoplight or driveway/parking Lott bumping) My car typically spins 2k+ rpm cruising at 55 and close to 3k rpm at 70 then would that 220 peak singer do the trick?

[Jhunt94]

yeahhh you're going to want an alt. I had around a 110-120 amp alt in my truck stock, installed a T1500 and a T400-4, and the voltage drop was very significant. Almost thought my truck was going to shut off a couple times lol needless to say it was not long before I had a HO alt.

In my opinion, the alt you listed would probably work in your application. As long as you keep the RPMs up it should be fine, if you want to demo with the car parked, you'll probably need to rev it up.

[Broke_Audio_Addict]

200 amps or close at idle would be what I'd want with that setup.

Considering I pretty much never bump at idle (no stoplight or driveway/parking Lott bumping) My car typically spins 2k+ rpm cruising at 55 and close to 3k rpm at 70 then would that 220 peak singer do the trick?

I like to base my electrical needs off of the recommend fusing from the manufacturer even though it's likely that you'll never see that much draw.

For you that's 350 amps worth of fusing.

The reason I said 200 at idle is because you need to factor in all your factory stuff like light's, ac, and other stuff like into you current draw.

If you have a 115 amp alt just assume your factory stuff consumes 80%-90% of its output.

So let's do some basic math, let's assume your stock stuff consumes 80% of your stock alts output so about 90 amps.

Now let's also say your amps will only consume about roughly 50% of their max potential draw on music, that gives them a draw of 175 amps on average while playing music, now add the 90 amps all the other stuff consumes and your at 265 amps of draw.

Now you can see why I'd recommend something that does 200 amps at idle, which usually would put it at around 250 amps at cruising speed.

Could you get by with less?

Yeah.

But really it wouldn't save you much money to get a smaller Alt.

[Wehan]

200 amps or close at idle would be what I'd want with that setup.

Considering I pretty much never bump at idle (no stoplight or driveway/parking Lott bumping) My car typically spins 2k+ rpm cruising at 55 and close to 3k rpm at 70 then would that 220 peak singer do the trick?

I like to base my electrical needs off of the recommend fusing from the manufacturer even though it's likely that you'll never see that much draw.

For you that's 350 amps worth of fusing.

The reason I said 200 at idle is because you need to factor in all your factory stuff like light's, ac, and other stuff like into you current draw.

If you have a 115 amp alt just assume your factory stuff consumes 80%-90% of its output.

So let's do some basic math, let's assume your stock stuff consumes 80% of your stock alts output so about 90 amps.

Now let's also say your amps will only consume about roughly 50% of their max potential draw on music, that gives them a draw of 175 amps on average while playing music, now add the 90 amps all the other stuff consumes and your at 265 amps of draw.

Now you can see why I'd recommend something that does 200 amps at idle, which usually would put it at around 250 amps at cruising speed.

Could you get by with less?

Yeah.

But really it wouldn't save you much money to get a smaller Alt.

Ok now I see what you are laying out, makes sense. I'll check and see what my options are in that particular flavor.

[everybodyknowme]

I was just thinking cost efficient. I know the price difference for my alt was like an extra $125 for 30 more amps. Naw I'll pass if it was me in this scenario. But I'm also cheap:)