Interesting. I have been having similar problems. Using a single YellowTop for both cranking and stereo.
With all of the stuff recently put into the car (including the constantly running twin fans) and my voltage is WAY low (11.9 - 12.5 with ANYTHING turned on in the car, if everything is turned off; 13.2) as indicated by the Navigator Pro.
after having some problem with fuel supply and heavy hitting stereo, I am having a beefed up alternator made for me by Ohio Generator.
It should be installed in a week or so, and I can tell you if it has fixed my problems.

 

I forgot to add, I have the stage II AAM fuel system with the big ol Bosch fuel pump, another draw on the battery.

 

Yea, I have the Stage II fuel system + the whole HKS EMS suite; EDFC; Turbo Timer; Methanol controller; GPS Navigation; 2 flat screen monitors and a 1000 watt+ stereo w/ 4 amps, 4 subs, 4 component speakers and 2 mids.

Definitely pushing a lot of electronics. But I did not have a noticeable problem until we started upping the boost and adding the new fans/Meth kit.

 

sounds like you're forcing the alt to charge constantly,they fry in a hurry like that.

 

just swapped in a different battery, brand new one, to test, same issue, so, ruled out, not the battery!!!
will have a new alternator here in a few days, then i can test some more...

 

You can take apart the alternator and replace the regulater but i called nissan today while i was at work and the rebuild kit cost,s more the a reman alternator.They also said it would take about 2 week,s to get it so i would just replace the alternator and some how sheild it against the heat from the turbo,s.

 

have an alternator coming in real soon, will do...was planning on wrapping it with heat shielding as well

 

get that new alternator yet?

 

If you swapped in a new battery and the issue was there off the bat how are you sure its the alternator.

I would have charged the battery on a trickle. Disconnected the ALT then tried cranking. Alternator can't over volt the battery and you'd know 100%.

 

Cranking is fine, it is at high load, high rpm spikes, the alternator can't keep up, and the voltage drops

I checked a normal, stock 350z, alternator; disconnected line from alt to battery, checked volts, saw as high as 15.9V, so my previous check was insignificant, under NO LOAD, not connected to the battery, our stock alternator will show up to 16v under high revving.

New alternator will be here today, installed a second battery for my stereo system to reduce draw on the battery/alternator. Wish me luck

 

ohh ok.. I see what your saying. Keep us posted once you get it in there.

I spent the ENTIRE last summer with electrical issues in my Skyline. I know first hand how much of a ***** they can be. Mainly cause there often so hard to pin point.

So untill your on your 4th alternator, 2nd battery and about 50hrs under the hood you've still got it good..

EDIT: Not to mention being on a first name bases with the local tow truck drivers...

 

Sorry to drag up an old thread, but I just installed a higher amp alternator, from these guys and it seems to be working out great for me.

They offer a 200 amp alternator which is a direct fit for the stock 110 amp alternator.

Dave