Accessories generic usb charging cable vs OEM

[chicagopro]

I recently bought a usb wall charger for HTC evo 4G from ebay so I can have a spare, but the usb cable that came with it was generic, and seems to charge the phone slower, and even slower when I plug it into a USB car cigarette adapter, is there a difference from a oem and generic usb cable?

 

[Tre Lawrence]

Oh yeah... they are not all created equal, as I found out after buying a few cheapies on eBay.