I have the stock alternator that comes with an 08' F150 XLT. I think it's somewhere around 140 amps ?
I plan to get an aftermarket 250 amp alternator as soon as possible..... but hope to be able to get by with my stock alternator for a little while anyway.

My amplifier uses a 250 amp fuse.... So I'm guessing that it might draw like 150 amps continuous, and maybe 200 amps peak ? Haven't found that in my amp manual, but anyway.

Also, I'm going to be running an extra, big, fat group 29 or 31 deep cycle battery, with a battery isolator.

So yes, I will be putting quite a beating on my stock alternator.....

What do you give it ? A month ? 6 months ? A year ?

Thanks,
Fish

 

what is the power rating of the amp?
P/V=I or V x I = P
14.4 x 150 = 2160 watts
14.4 x 200 = 2880 watts

you running 2000 watts continuous, daily? if so your alt and batt are gonna give you the finger and jump out of your truck

 

well I could tell you the "wattage ratings"...... but the amp is so "underated" that it would probably be much more accurate if I just told you that my specific amp was bench tested at 111 wts x 4 channels into 4 ohms + 705 wts x 1 into 2 ohms for the sub channel (its a 5 channel, class BD amp) So to answer your question, no. Only a mere 1150 wts, and of course that wouldn't be all day, every day.

I guess RF uses a substantially larger fuse than they would really have to, as well.

So anyway, now that you know some of the specifics of my amp, back to the original question;

Running this amp, and a second large deep cycle battery, how well, and for how long do you think my stock alternator should be able to handle it ?

Thanks,
Fish

 

I am running stock alternator with just regular battery up front with a kinetik 2000 battery in the back. I am running a Sundown saz-1500d at 1 ohm which is 1500 rms x 1 at 1 ohm and a sundown 100.4 4 channel with all 1/0 gauge power wire. My lights dont dim and I have had no problems with it yet. I am not sure what size alt is has stock. But, a guy i have know for about 10 years that works at local stereo shop has always told me to just run 1 or 2 extra batteries in the back and I have never had a problem with stock alternators. I ran a 70 amp alt in a 95 civic hatchback with 2 kicker zx1500.1's and a kicker 850.4 for over 2 years without a single problem. I just ran a small kinetik up front and a kinetik 2000 in back.

 

If you use a fuse that is grossly over sized it is worthless...it won't trip when you need it to.

You aren't drawing "200 amps" considering total peak output of your stock alternator is in the 140 range, and you have to factor for other draws from the truck itself.

Then factor in that you likely don't EVER come close to needing/using max rated output on the amp, you aren't even close.

Do your lights dim when you crank it up? If not, you're well under 140 amps draw...

 

even at it full rms power, your amp should only be drawing about 80 amps (with the car running). and if you aren't running it that loud very often, you really should be fine with your stock electrical system. unless you want to run it with your car off, then you just need a couple batteries

so to answer your question: your stock alt should last forever, or as long as it normally would

 

That sounds great ! An upgraded alternator is not something I really wanted to mess with / pay for, if I didn't have to.

Hey Lumador I hear you about this, and this thought definately crossed my mind. But then, I'd think that Rockford Fosgate must know what they are doing.
I think I'll ask about that HUGE fuse on the RF forum.

Oh, but yes, I do often play my stereo with the truck off, which is my primary reason for an extra battery, and isolator.

Peace,
Fish

 

Fish, make sure to do the Big 3 upgrade. You will be fine with the stock Alt.

 

upgrade the body to chassis ground behind the front passenger tire.

 

x2 i did that with 0 awg. Overkill LOL.

 

4 awg here

my amps are already grounded to the frame

 

Yea' I copied and printed the Big 3 upgrade for my mechanic. I'll tell him about the body to chassic ground upgrade as well.

Peace,
Fish