heat + power drain in wifi adhoc?

You could be damaging your battery by getting it too hot. Be very careful, if a battery gets too hot for too long the acid inside will start to evaporate causing the battery to bulge. At that point the battery will never hold a good charge and if continued, the battery can explode. I've done a test with exploding a phone battery and I'll tell you this, if that battery goes while it's in your pocket, good luck walking again.