The rating on the charger is how many amps you can
pull out of it, the voltage is how hard it pushes. So you won't hurt your devices. If you connect the lowest rated charger to the device that normally uses the highest rated charger, you might over-heat the charger, and the device will take longer to charge - the device won't be hurt, but the low-rated charger might burn out. I generall use my 1-amp, 5-volt USB charger for all my USB rechargeable devices. -- Except I have one or two devices that seem to require some sort of specialized smart charger to make them charge. You'll know the first time you try to charge one of those with an ordinary charger
