Nervous

howie777

OK, now I'm a bit nervous. I am awaiting the arrival of my 2 MM12 subs. I will be running them off of 2 C300.2 amps. My question is, can I damage my alternator/battery with this set up? It was suggested I get a 1 farad cap (or 2) to store the extra energy for when the subs needed it. Then I read that caps can cause damage the alternator somewhere. So what should I do? I have a GM car which I was told basically doesn't come with a great altanator to start with. A second battery/altanator is out of the question.

1) 1 amp + 1 sub
2) 2 amps + 2 subs (already paid for 2 and 2)
3) 2 amps + 1 cap + 2 subs (already paid for 1 cap, rec. 500 RMS per cap which is 1 amp in my case)
4) 2 amps + 2 cap + 2 subs

Thanks

Howie

exalted512

caps only damage the alt. if they put too much of a load on the battery/alternator
hence if you have a 25 Farad cap, that might do more harm than good
what kind of battery do you have?
is it stock?
if so, get a better battery, energizer batteries are really cheap and seem to work pretty damn well...i have one in my truck, Vince has 2 in his, or at least did, im not sure what his current set up is like
and the biggest one they have is only like $90
so id grab one of those
also, upgrade the big 3
after thats done, add a cap or 2 and i think you should be fine
-Cody

neomagus00

well, the damage also depends upon what you do with the cap - if you drain it completely with every bass hit (not gonna happen with your setup), it may damage the alt. but, if you only use like 0.1 farads of that 25 F cap, it won't hurt a thing. it's all in usage.

pOP

what do you mean by big 3?

exalted512

all you ever need to know on upgrading your electrical system
-Cody

AustinKP

Dang Jerry, that's an excellent explanation. Very well put together, and you explained it in layman's terms. Nearly perfect. :Thumbs Up:

exalted512

actually, I didn't write it, its written by Chris(Geolemon)
he has articles that explain pretty much everything you need to know about car audio, and all explained in terms everyone can understand
-Cody

AustinKP

Oh, that's right. I saw geolemon in the address for the site, but for some reason my brain processed Jerry's Lil car w/ 12's...so...great job Chris!

bknauss

Originally posted by pOP
what do you mean by big 3?

I wouldn't follow this site. The guy seems to have some knowledge, but its not exactly correct.

1. His "tests" or whatever you want to call it for caps isn't real world. Richard Clark, who is mentioned in the article, has many articles about caps, has done real world tests. I would definitely follow what Mr. Clark says since he is one of the foremost researchers in the car audio field and has real world experience with car audio

2. The big 3 isn't really all that great of an improvement. I just listened to a friends competition car this weekend. He has a stock alt with some a new Optima battery and proper wiring, but none of this big 3 upgrade crap. According to the fuses on this amps, he's got the potential of drawing over 200A. With his proper wiring (power wires, fuses, etc), there was no dimming of headlights. Scott Buwalda is using everything stock under the engine in his Altima, and he's drawing probably over 200A, but again, he doesn't have to worry about dimming lights.

3. His order of upgrades is a BIT off. Proper wiring is definitely the top thing to worry about. Second would be a new alternator since that's the thing that actually provides the power. Battery upgrades are generally next.

The guy definitely has good knowledge, but he's not applying it correctly.

As for caps, here's a good discussion from carsound.com with numbers provided by "Rob M". This is more for SPL guys
http://www.carsound.com/cgi-bin/UBB_CGI/ultimatebb.cgi?ubb=get_topic;f=1;t=017187

And if you need to do something on your lunch break, here's a 7 page "discussion". Lots of good info here
http://www.carsound.com/cgi-bin/UBB_CGI/ultimatebb.cgi?ubb=get_topic;f=1;t=020321;p=1

howie777

So will it be happy days for all car audio people when the OEMs switch to the 42 V systems with the 36 volt batteries? Sounds like it to me, although there will be that transition period to deal with...

I think I'm going cap less for now. I do not want to kill my alternator! Maybe get a new batter as well.

Thanks for all the help/advice everyone. All I'm waiting on now is the subs to come in, its all pre-wired to the truck now. Although I should have measured the truck BEFORE ordering two MM12s and 2 C300.2 amps.

Howie

exalted512

some people have other priorities besides car audio in mind
the last thing i would do is an aftermarket alternator unless you KNOW youre going to be drawing more current than you alt. can handle
its a $350-400 upgrade
it DECREASES performance
my truck has 255 HP stock, not at the rear wheels
this may sound like a lot to some of the guys with small cars on here...but this is a 3/4 ton truck thats used to haul and it needs power
if i got an after market alternator i would have to do other mods to increase my torque and horsepower to make up for it
i would much rather get 2 batteries...its only about $180 if you get 2 new energizers(900CCA)
he has listed the stuff in order of what the normal person should do
most people who have a "system" have a 4 channel and a 300 watt sub
he has them in order of the most cost effective way to upgrade
i mean the big 3 costs all of $10 max if you get ripped on wire cost
caps are like 60 bucks
you cannot tell someone they need an alternator unless you know the amps their current one is rated at
thats being a 'tard
a lot of "high output" alternators are rips anyway
they put out really high amps when your engine is running at 4k rpms
my truck does 70 at 2krpms
idles around 1200
so if you do plan on getting an aftermarket alternator, make sure it puts out a lot of amps at around 1200 rpms because thats where it matters
-Cody

exalted512

oo, and btw, 2 Farads will NOT put so much of a load on your alt. to damage it, i doubt the alt. will even "know" theyre there
i like to have at least 1 cap to "even out" the flow of power
-Cody

AustinKP

Wow! Those are seven l.o.n.g. p.a.g.e.s... Read through them all though. Definitely above my level!
-edit- dang, there were 3 or 4 new posts by the time I read that. Cody, your truck idles at 1200? Isn't that a little high? Mine idles around 750.

exalted512

actually yeah, it is a little high
1250 is idle in neutral with the a/c on
900 in park
-Cody

LittleCar_w/12s

Well, cody, all I can say is that an alt. will only draw HP if you are drawing tha amps from it. If your elec system uses 0amps, the alternator will only have bearing friction

However, if you crank up your system, turn on the high beams, and the fogs... not only do things dim a bit, the alternator will pull a lot of HP. My engine is small enough that it actually slows down from idle when this happens :eek:

-Jerry

neomagus00

hehe - i have a friend that has to turn off the a/c to make it up a hill at an appropriate speed; the compressor draws too much power for him to stay at 65-70 on an incline...

i wouldn't call 1250 idle high (at least from what i know) - mine's like 1100.

cap - unless you're a crazy spl competitor, it won't damage your alt; think about what you have now - you're drawing current straight from the battery and alt at a rapidly varying rate (make sense?). you put a cap in, the amp uses the stored energy of the cap (which can be accessed faster than that of a battery, btw, better transient response). all the battery/alt system sees is a cap that needs to be filled at the other end of the line, so it sends a continuous supply down the line until the bass note has ended and the cap is recharged.