I just now caught the part about you using this on a triple xp-g2. 
That makes more sense then, thought you where using a single led. 
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You could still use a amc7135 for modes but it wouldn’t really be doing anything besides modes if its set high enough. I would think if you used a amc7135 driver set to above 5 amps and used thick guage short wire every where and maybe spring resistance mods that 5 amps would be feasible. I’m pretty sure the PD will handle the load. In Djozz graph you would need 3.4v to make 2 amps to each emitter but the battery would see a 6 amp load which it looks like it could handle.
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Didn’t know if you had seen this or not.