From a technical point of view I can't see how one would charge faster than the other. My only thoughts on this is that one of your cables must have had an issue of some sort. Bad connection would be my first guess. Assuming they were the same length.
Keep in mind that there are other factors you don't realise. When a cable gets longer you have a voltage drop, the longer the cable the bigger the voltage drop. When you're dealing with 24VDC and small current the drop can be significant as you go longer. This is why there is a maximum size for USB cables that act as power cords.
Saying that 3m should be fine for charging. I would suggest buying a USB cable that is quality built and tested. Be wary of anything that is overly cheap.
09-12-2014 05:08 AM