I know of one vendor that states onboard battery charging via USB could shorten the life of batteries and/or the device itself. With regard to the device, I think the concern was that the USB connector itself could be damaged/worn out by repeatedly plugging & unplugging. But, the batteries too? They recommend charging the cells in a dedicated charger. I usually do use a charger. But, it sure is convenient at times to be able to use the onboard charging capabilities. Is this a real concern?