Do not hook an LED array up to the battery. I know a guy who did that and things got dark in the woods.
Seriously, the charging ckt. is approx 15W, so anything more that that and your in a constant loss mode. My lights worked perfect at the 24hr race. For a rectifier, you don't need a high electrical capacity, but the smaller bridges are primarily for PC board applications. A 25A -35A part with Stakon terminals, mounting hole, and alloy case is cheap and easy to deal with as far as mounting, and 5 or 6 times the capacity so you will not have a problem. You just have to observe one thing, DO NOT connect the - output of the rectifier to any other gnd on the bike, it goes to the light only. + output to light + of course and the AC input terminals to the AC power of the stator and gnd. You can use the headlight connector as a supply to the bridge. LED arrays have their own internal driver and operate over a wide voltage range so an additional regulator is not
needed. Here is an example of bridge rectifier :
http://www.mouser.com/ProductDetail/Gen ... Fo5g%3d%3d