Dear God, i just ran the numbers I wanted to using DITL.ORG's numbers, and here were my results.....
First, I had to figure out a shield number for an ISD. I used the Accalamator's Shields and Length, figured out meter:gigawatt ratio, and applied that to an ISD's length. This gives an ISD 149 Trillion GW shields.
(I rounded up from 148.9 Trillion GW)
Then I go to DITL, and get the ship info I need from them. Basically ship name, what they think the number of ships are, and shield power. Here's a mini table.
Class Num Shields in Terrajoules (see below for watt conversions)
Sovereign Class 10 4590000
Galaxy Class 30 2700000
Akira Class 100 1876500
Ambassador 40 2025000
Constellation Class 5 418500
Defiant Class 24 2376000
Excelsior 200 1201500
Freedom Class 10 1039500
Interpid 35 729000
Nebula Class 25 2565000
New Orleans 10 958500
Prometheus (MV) 1 3915000
Trident Class 5 742500
Raider Class (Peregrine) 150 229500
For a grand shield total of 812 Billion Gigajoules (which is below the limit of the ISD by quite a bit, like 99% less)
Assuming all the Federation ships hit with there deflector beams (for this arguement, we assume they can still fire torpedoes so they don't think it's suicide, or they think they will blow the Star Detroyer up so it's worth crippling the fleet for a few days for repairs)..
Shields on the ISD: 149,000,000,000,000 pre hit
Shields on the ISD, POST Hit
Assume 1 GJ = 1 GW
(i.e 1 GW per second) 148187786000000 GW
On the Bridge of the ISD:
Bridge Officer: Sir, reading 500 hits, equal to 62 seconds worth of Turbolaser fire. Shields at 99.45%. The enemy ships have lost power. They appear to be firing low yield warheads in the 100 megaton upper ange.
ISD Captain: They must have been in drydock refueling or something.
Either that, or these are ships used in some bizarre alien "21 gun salute" welcoming ceromony. It would explain the weak weapons. Oh well, Just ignore them.
Assume 1 GJ = 15 GW (i.e 15 GW per second, the same rate a Turbolaser cannon): 136816790000000 GW
Bridge Officer: Sir, Reading 500 hits, Shields at 91%. The enemy ships have lost power. They are firing low yield warheads, no threat to the shields
ISD Captain: That was a little Impressive. Disable the ships with Ion cannon fire. We might want to look over those weapons, they seem to be a bit better then Turbolasers. Ignore the warheads if they are not a threat, they just might be escape pods or something.
Assume 1 GJ = 150 GW (i.e 150 GW per second, 10 times that of a Turbolaser): 27167900000000 GW
Bridge Officer: Sir, Shields at 18%, but the enemy fleet has lost shields and primary power. They are however firing low yield warheads at us.
ISD Captain: Impressive. Disable them with Ion Cannon fire, we will want to look over there weapon systems later. As for the Warheads, just shot them down. Why would they bother with such low yield warheads anyway..
I think you would need ALL OF STARFLEET (assuming they have at least 5000 ships) and possible the Klingons, doing the deflector dish trick to stop an ISD.
I hope everyone joyed my Imperial Officer comments.