This is the second pair of wonderboom we bought. 3 of the speakers stop charging after less than 100 hours of use, the third speaker only last a couple of hours on a full charge. Unfortunately they are out of warranty. We have tried all the reset methods advised by the manufacturer including factory reset, tried to plug them into to laptops, etc. We have been told that it could be a battery issue a usb issue or a software issue. Basically too many possibilities of malfunction for a very expensive and badly made product