Hi Melanie and mister_e

I tried using a 100 ohm gate resistor. I also tried a 1000 ohm gate resistor with a gate to source reverse biased diode, this also caused the gate to short out. I also tried a separate power supply to bias the gate (grounds tied together) with the same results. The gate spec is +-16 volts.
I am using the IRL2505 and then the IRL3103D1. I looked at the spec's again on the IRL2505. I think I know what's wrong. The continuous current is rated at 105A I am drawing 24A. The unloaded gen output is 11.6v, I need to check the loaded output across the Mosfet, I believe its around 8V, this puts me right at the Power dis. rating. I will try 2 fets in parallel, I hope thats the problem.

Thanks for your responses.

GregK