recently on a very hot day(103F), our astro van shut down. any ideas.

started engine, started to drive. first radio shut down, then noticed all gauges had shut down, van continued to drive but with minimum power..no acceleration when gas pedal was pressed. shifted into neutral and back to drive, momentary conditions to normal, then once again no radio, gauges etc. van continued to drive but with minimal power,for about one mile, then finally engine shut down, pulled over to side of road. while there, power to radio, roof cosole readouts, and power windows operational. tried to start, starter clicked due to low battery power... i assume.