[RICK LAKE]

Tony Radford Couple of questions and a couple of answers
How many wire Alt are you running to regulator in housing??
Who's pulleys are you running and is the crank undersized?
What is the ampage of the Alt?
Size of battery, CCA rating??
If your fans are running at idle, this is the reason for the 11.5 voltage check. Your alt is not charging the system from idle because of alt speed and possible small output.
Tony said here's what I have gone through. I have added curcuits to my car that started with a 70 amp system. I have ther under sie march pulleys. It doesn't spin the Alt fast enought at idle to charge system. Ouput is 35-38 amps at idle. I have 3 fans, fuel pump, Msd ignition system, high voltage coil and ECU. At race speed the Alt is ok but not charging enough to the battery. Forget at Idle the - reading on the amp meter. The battery is being drained. I ran a 880cca and it would kill it over a 3 day event. Had to charge battery at night.
Fix to problem, Have to start with the ampage gauge in the dash. Spikes in ampage can be in the 120 amp range depending on what load comes on like 3 coolant fans, starter, or secondary systems. The pastic that insolates the 2 posts on the back of the dash could melt and burn the WHOLE system depending on how this gauge is installed in the the car and if it's the MAIN power feed. 10-12 gauge wire, IMO is not enought for supplying all the ampage at times. Replacement of the amp gauge with a voltage gauge to start. Connect the 2 main feeds togeather and add a small power feed to the voltage gauge and a ground. This will give you an correct reading of the charging system. You are looking for 13.7-14.2 volts for good charging of system. I am using the orginial wiring system from ERA. I added a 125amp maxi fuse in the charging cable from the ALT ouput terminal. #4 gauge wire to battery post on starter soleniod. The Alt regulator from the old system is external with 4 wires. PAperformance sell a kit for cobra with an 100 amp alt, kit for the external regulator to swap over to enternal one. A 1 wire mode is needed for the new system. The wire is a wakeup for ther charging system. I start my car and the volt meter goes to 14.2 volts and charges both the battery and handles the loads of the car without any problem. Battery stay fully charged. Life time warrantty on the kit. You can run under size pulleys and have a good charging system. Good luck with your car. Rick L.