I am getting a multi-purpose lithium power bank to recharge/run my notebook, iPhone, iPad and planning on using one which can jump start a 12V vehicle. Some of these have switches to select from among three different voltages for their usb charging ports. I was looking for specs on the notebook power supply in hopes of getting info to choose the most compatible power bank for it but the only spec given is that the supply is rated at 87W. Am I correct in thinking that any voltage will work with my battery powered devices and higher voltages will simply charge them faster?