hello John MI,
i am using exactly the same dump controler. my battery bank is 60 volt, but tapped off 1 single 12 volt batt to operate (not the best idea but it does work and will have to do until i make mods for 60 volt)
over night we have had a major snow storm ans winds are severe. my controler is almost staying on constantly as i am often surging past 40 amp into the bank.
mine does operate the same way, shifting to dump when there is a large surge in amps and drives the batt voltage high. currently set at 12.6 and 14.6. i use my bank for a heating coil arrangement.
been on this dump controler for a little over a month now. batterys do seem to be happy.
personally, i think the unit is doing quite well what it was intended for. but thats my opinion.
zubbly