Default otg cable for charging my Bluetooth headset SBH50

Is it safe to use otg cable for charging my Bluetooth headset SBH50 on the go using my note 3 battery as charging sorce????

By the way, been using SBH50 for more than a month now have no problem recommending this device to anyone looking for a wireless Bluetooth option for cellular or audio listening needs I'm definitely impressed with its functionality and sound quality. However the battery charge do not last more than two days even without use at all (standby only) and less than one day with light use (about one hour calls) although sony says that SBH50 minimum Rated Talk Time: 8 hours, and Minimum Rated Standby Time: 400 hours
I don't know if it is my Headset problem or it is actual battery life for this type of sony headset ??
Dr. Monzer M
Alcatel OT View, siemens S55, siemens c72, Sony Ericsson P910, HTC p3400, Imate jasjar, HTC Touch HD, Zte skate, note 3