Wow Greg, sounds like you have a SAWEET setup! You've probably got a sweet range. 48 cells would be what...178 volts fresh off the charger? Probably very little sag too with that many ahs. I feel a little more comfortable with my 168 volts fully charge now
. I've been using the light bulb method too, coupled with a voltmeter just to be sure, but mines a 25w 110 bulb, probably similar resistance, I can't believe it hasn't burned up yet.
Also, I'm using two computer heatsinks from a G5 mac (they're huge because apple doesn't like their fans to run). I think you'll be pleasantly surprised at the difference the sinks will make.