Electrical load problem

Hmmm. Having some posting problems here. My apologies if this appears twice.

If you can start your car without boosting the battery, it is very unlikely that the battery will be the cause of the engine dying with electrical loads turned on. Similar thing with the alternator. Your car should run till the battery dies if the alternator is not working. This would take more than a few minutes to happen. Cranking the starter is probably the single biggest load you can put on your battery and the alternator does not kick in until the engine is turning at least a few hundred RPM, how would the car ever start if you relied on alternator output alone to supply ignition?

Much more likely is a voltage drop between the battery and the ignition module. This can be checked by measuring the voltage between the + battery terminal and the common point of the ballast resistor. Red lead of the meter to the battery + post and black lead to the ballast resistor common point. Take note that the common point is NOT the wires going to the coil or to pin 3 of the ignition module. If you see more than a volt, or if the voltage goes up when you turn on the heavy loads, dig out the wiring diagram and start troubleshooting. Make the same check on the negative/ground side of the circuit by checking from the battery - post to the case of the ignition module. You can verify a cure by temporarily running a jumper from battery + to the common point of the ballast resistor. (classic hot wiring). Same for a fault in the - or ground circuit. If you now can turn on the heavy load accessories without killing the engine, you know the problem is in the wiring.