Trojan says to use 10-13% of C20 to recharge Gels
C20 is the AH capacity using the 20 hr rate (which is a discharge rate of 5% of capacity, C/20--capacity divided by 20 )
So the OP's two 100s would be recharged at 20-26 amps, max. If they were AGMs that would be 20% of C20 or 40 amps.
AFAIK, discharge and recharge limits are the same to allow time for the chemical reaction in the battery, but not sure on that. If so, then max inverter draw on the two Gels would be with a 260w 120v appliance, or 520w with four of those 100AH Gels
However we usually say you need about 440AH to run a microwave which is say 140 amps, so that is 140/440 = 32%, and recharging AGM or Flooded batts at 32% is allowed. My AGMs do say 27-30% though.
https://www.trojanbattery.com/pdf/TrojanBattery_UsersGuide.pdf
