Hi I really need a USB water pump (small). I have found one in China but they need payment in a different currency so its proving difficult. I would much prefer a US/EUROPE seller. Cheers.PSgt; If I had to pay to get the power supply changed from wire to USB then I could if anyone knows who could do this.
The USB output has a 5V power supply. USB2 delivers up to 500mA and later versions may be 900mA. USB hubs start off with less than this (100mA) but change as they are initialised. Some dedicated USB charging ports supply up to 1.8A. There are some USB power cables that take the output from 2 ports in a sort of Y harness (first link for example). The result of all this is that only a very small pump would run from most USB ports. I did find 2 rated at 5W and 8W but the voltage was not shown. I suspect they were mains operation, meant for large water bottles. If they were 5V they would use 1A and 1.6A respectively, so only run from special USB charge points or double cables, and only in some cases anyway. I assume you want to run from a Laptop/Notebook battery for convenience. The point is that even if the USB port can supply the correct voltage and current the battery would be emptied very quickly. It is probably cheaper to get a suitable pump, then power it from a separate and more suitable rechargeable battery or mains adaptor (wall wart), whatever it takes, taking into account how long it should run with a single charge. This is about the battery voltage and the capacity in ampere hours - the number of hours it can supply a given current. D size rechargeable (Ni-MH) would run a 6V x 6W motor using 1A for about 6 hours. C size cells are half that, and AA cells about half again. It takes 4 cells to get 5V. Get them as a pack though or at least with a battery holder, as they cannot be soldered. Then you need a proper charger. Recent laptop/notebook batteries are lithium ion types, 10.8V and 4.8Ah, so deliver 1A @10.8V for 4h more or less. Other types worth considering are for cordless drills.
