I was out last week in Big Bend NP and was in Terlingua when the temp dropped into the low 40s and we rode most all day in that temp and my heated grips were just barely warm, not enough to help with my gloves on. When I use them around here in Florida and the temps in the 60s they seem to work fine but anything below 50 and it doesn't help keep my fingers warm enough. Has anyone had the same problem and if so does the YES warranty cover it?