wiring options for dual 4ohm sub

Hi there. I have a lightning audio S4.15.VC2, dual 4ohm 15inch subwoofer in a sealed enclosure. The power handling of the sub is rated at 500watt rms. I want to run it off an Audiobank 4 channel amp with a rated output of 150 watts rms x 4 @ 4 0hm and 240 watts rms x 4 @ 2 Ohm. I need some suggestions on wiring options and would like to know what effect it will have if the channels on the amp are bridged.

Wiring the 2VCs in parallel gives you 2R (Ohm) hence 240W.

If 2 outputs can be bridged it should give 480W. (No good using 2 outputs otherwise - they must be out of phase with each other.)

Whether that amp is suitable however is another thing. IE - I presume it's not a 4-ch SUB amp (since subs or only 1-ch) and sub amps (should?) have filters to limit sub speaker bandwidth (to prevent sub overheating).
However, I am relatively amp & sub ignorant - the 2R for 240W & (appropriately) bridged 480W possibility is based on basic theory - and others should answer or confirm my last paragraph.   

I have wired the sub in parallel and bridged two channels of the amp. The amp is not a sub amp but a class AB amp rated at 2 Ohms. The amp performs fine and does not overheat but my battery runs down very quickly if music is played while the motor is off. Is there a way to prevent this through wiring the sub differently?

Yes, wire as 4 Ohms or unbridge your amp. That means half the output power and hence (over) double the battery drain time.

If you are presently running 480W output, that's an input of ~50A which would discharge a fully charged ~60AH cranking battery to its recommended lower limit of 80% SOC (20% discharge) in about 5-6 minutes.
Likewise if 240W, ~12-15 minutes.

Thanks. I will try that. I hope the sub still sound as sweet.