TWENTY-EIGHT AMPS!!!!! Holy Bejeesus! That's ridiculously huge. You should be down around 15amps max. I run an excellent engine fan, same as PJ, and a separate auto tranny cooler fan on the same controller and fuse and I only use 15amps.
I use a GM SI-style one-wire 105amp alternator. It doesn't begin the charging cycle until 1500rpm. I was running undersized crank and oversized water pump/fan pulleys to increase cooling efficiency, but that makes your alternator run slow and yet I still only needed to rev the engine to 1500 to start the charging and then I can ease off on the pedal and it would continue to charge at the 1000rpm my side draft required. I have an auto tranny that squashes the rpms down to 800rpm when in Drive no matter what you set the idle at and I would still have some charging, albeit a little lower. My FI mod has forced me to go back to the stock pulley sizes, so I should have a faster spinning alt and even better charging. I retain the use of the engine fan and my electrics only kick on at 180*. Under normal circumstances cruising around my engine only gets up to 160*, so my fans seldom kick on. Only when I'm stuck in traffic, a fairly common occurance, does the temp start to spike and kick on the fans. My funny pulley sizes made the water pump turn slower for better cooling efficiency at higher rpms, but at idle this would cause the engine fan and alternator to turn slower than oem. Going back to the oem pulley sizes should make my fan spin a little faster and provide better radiator cooling, plus improve charging at idle.
When I had a Combo cam I also disliked how the lope would mess with my charging at idle. Very annoying. Every time it lopes you're on the verge of stalling.
If I were you I would get a fan that doesn't gobble so much power. I'll see if I can find the fan that me and PJ use....