Charge/Brake warning on at high rpms/loss of power

[BadPanda]

I don't know what to think of this problem. I did an sr5 to Gts stock swap into my hatch. It was running good for a few months now. Though I did have to replace the battery and alternator. Had to use a new Supra 7m alternator because of availability issues. It worked fine for a month now.

The other night, however, I was driving to my friend's house, I went from 2nd to 4th making some decently high rpms (6k). I went through 2nd gear fine, then I got halfway through 3rd, the headlights got really bright, then the charge/brake warning lights came on and I lost some power. As soon as I let off the gas, it went back to normal. Now anytime I hit any rpms above 3.5k, it does this. The battery has 12.5v, and the alternator is pumping out 14.5v. Someone said that the wire from the alt to the batt could be going bad, or maybe the regulator?

Any advice guys/gals? I need a solution

**Update**
I forgot to mention, a few days after I changed to the Supra 7m alternator, the ring on the alternator wire (the two white wires connected together with the ring that bolts to the alternator) broke off and the wire arced on the alternator a few times. I had to replace the ring for the wires, using two ring (one on each wire) and bolting them together on the alternator.

I'm available through this post, and text if anyone has any advice. (208)-549-7676 (text only, can't receive calls). Thanks for any advice or tips!

[Red]

" the headlights got really bright,"
That was the regulator failing, or the white sense lead disconnecting, and the alternator voltage going too high.
" then the charge/brake warning lights came on and I lost some power. "
That was the alternator failing, probably as the regulator burned out, which it will do after one of the above.

Those two white wires, on the AE8x alternators, are the output lead, which should be the only wire on the output post of the alternator, and the voltage sense lead, which comes from the pack connector on the alternator. The charging output wire should be a heavier gauge, but Toyota in their infinite wisdom uses the same wire for both.

What is happening to you sounds like the regulator has burned out and when you build enough RPMs the alternator voltage goes too high. Which will burn out the headlights and marker lights first, then the radio, then the electrical system. Unless you are lucky and the only problem is the white sense wire being loose. If that gets disconnected, the alternator voltage goes too high. If that wire is solid, test the alternator voltage at high RPM. If it goes over 14.4 at any time, for any reason, pull the alternator and repair/replace it.

The AE88 engines rev very high, the alternator and pulley have to be built to take the extra speed. I'm not sure a Supra stock alternator would work properly at high rpm.

[BadPanda]

I'm definitely going to get a gts 4age alternator soon as I can. I got the new supra alternator for now (traded it out for a new one) and it's doing fine for now, but I want it to be right for sure. Thanks Red!