LG HG2 (chocolate brown, 20amp CDR, 3000mah) or Samsung 30Q (lavender, 20amp CDR, 3000mah)
Being the iStick100watt is a parallel battery setup (both positives up, both negatives down), voltage is the same as a single battery, but load is balanced on both batteries, to Mah and Amps appear to be double, so in this instance 6000mah run time, and 40amps CDR.
Ohm's Law for Regulated mods (Watts/lowest voltage/90% chip efficiency=final amps, with a parallel mod we divide final amps by 2 gives the load each battery is pulling sepperately)
100watts/3.2v (low battery shutoff)/31.25/0.9 or 90%=34.72222_ final amps. 34.722222/2=17.361111_amps each battery has to supply, plenty safe
+1 for asking