Alternator Upgrade & 2nd Battery

I need to upgrade my alternator since I installe dmy new amps. The amps I have are in my sig. They output about 800w RMS combined and 2200w Peak combined (if the birthsheets are right). What would be the amprage that I am looking at drawing? A=W/V?

I was thinking about going from the 90 Mustang stock 80 amp to a 130 amp unit and I want to make sure it is going to be good enough. It outputs 80 amps at idle and 130 amps at 3000 rpm.

Also, should I look into placing a second battery in my trunk with the setup that I am running? And could the second battery just be a matched Ultmia Red Top like I have in the engine bay?

Sorry I forgot to show my sig!

I have a RF P4004 @ 400w RMS and a RF P3001 @ 350w RMS

Actually, I'd be surprised if you needed to upgrade anything.  Hook it up and see.  It can never hurt to upgrade your alternator, but a second battery would be completely unnecessary in your case. 

The exception would be if you were to play your system on the secondary battery with the car off for long periods of time.  Then I'd recommend a deep cycle (yellow top) and battery isolator.

Good luck.

Well something must be wrong with the alt or something, since you are the second on eto tell me that the setup should be fine. I have a Red Top in the car now btw. After hooking up the stereo and testing things out, I get the voltage gauge dramiticly dropping! I am thinking, after reading a couple great forms, about doing a couple of the big 3s. I more than likely am not going to be doing what looks to be one of the more critical one though. The power from the alt to the battery I am not sure I can do because of the way the alt hooks into the elec. system. It is through two plugged connections, so I have small guage wires running to a plug harness and then into the alt. If I upgrade the alt, I can use a 4ga wire witha ring terminal going to the battery.

lqdfx.. ur going about this the right way... upgrade the big 3.. and put a 4ga wire from ur alt. to ur battery with a simple ring terminal will work fine..  u still may need to upgrade the alternator.. as people neglect the amps that ur car needs to run before u added the stereo system..  and with ur wattage u need about 80 just for the system and ur car needs 20-30 amps.. so if ur alt. will put out around a 100 amps ur fine but if not u may need to upgrade..

You could take the alternator out and have some shop bench test if first.  Then make your chioce of replacing it.  Just a thought

John........

steezs:  voltage drop is measured at the battery and at the amplifier.  Resistance reading is from the ground of the unit you're testing to the car battery negative.  Usually an extension of heavy wire is necessary to reach both places with the meter probes, so you measure resistance of that wire and figure it in your calculation.  Any two ground points can be measured for resistance.  Read the grounding stickies at the top...it's covered there.

arrrow:  I don't think you do but it sure is a good idea to fuse all power wires.