On my MAP I use either 2.8 or 3.0 I have no problem @ 5 volt The MAP Tanks seem to run cooler I would guess because of the amount of juice they hold. For 5volt with an atty, standards will run a little hot but if you jump up to a HV it almost becomes like using a LR on a 3.7 volt device. Hope this helps. I really enjoy the MAP @ 5 volt over a atty, currently using a 2.8ohm running on a Tekkeon using either 60/40 or 70/30 mix PG/VG