Yes jump a wire from the battery to isolate the rest of the circuit, 11 volts is to low in the real world, check your bulk head connector, the voltage at the positive terminal on the alternator and last but not least the voltage drop across the AMP guage. You should have at min. with engine not running 12.5volts, about 13.8 volts with engine running. I have had to change a few wires and terminals on my Challenger to achieve the desired voltages, and yes I have soldered every terminal that I can.