Has anyone else experienced very high battery drain in these devices? We sold few SP20s and all of them complain of high battery drain. One customer claims the 6800 mAh battery drains in 2 hrs! I have noticed with our demo unit also that battery takes extremely long to charge and discharges very quickly. I think these batteries are poor quality. Are the batteries same on TDC150 as SP20? Is there a plan to release better batteries for these models?