thanks for the ideas. unfortunately, at this time, everything is in a remote (100' from the house) enclosure. if i had a good way to get the heaters in the house, i'd probably have all my other control electronics in here too! i built a 2 compartment box, fully insulated. one holds the batteries and the other the charge controller, battery distribution blocks, turbine rectifier, turnigy meter, thermostat/relay and my heat source (a pair of 35w mower headlights). as of now, all of that power will just be used to keep the controller side of the box warm, which shouldn't take much.
on thinking further, i think i really only need to dump the turbine power if i was to get too much during the windy winter. i only need to monitor 'full output' on a handful of days...like a dark overcast rainy day, a full sun day, partially cloudy day, etc....i just want to know what production would be under these conditions...so next year when i have the system on its permanent load, i would know that on the overcast day...i will only have 500wh of production that day. i have access to a cheapo 24v inverter, so i think i could even use this on those specific days to provide a decent load to the system and get the output near its capability.
i'll do some messing around w/ the dump function and see what happens. i believe in dump mode, the xantrex has: voltage on, a programmable time delay (be at xx voltage for xx secs before activating), the voltage off, and another time delay setting (might be same as the on setting, don't recall offhand).