EFLAEC308 is used for joining two, like capacity packs in series to increase operating voltage (combining two THP42003S2PPL packs in series for use as a single 4200mAh 6S2P pack).
We have discovered that some E-flite EC3 Battery Series Harness, 13GA, part number EFLAEC308 have been assembled incorrectly at the factory. Connecting the series wire harness to the Electronic Speed Control in your model will result in failure of the speed control and possibly other electronic components.
During the course of manufacturing of this wiring harness, the battery connector, which plugs into the speed control, has been wired incorrectly with the polarity reversed. If your Battery Series Harness does not match the photo, it is wired incorrectly.
Do not use this wire harness and please contact Horizon Hobby Product Support at (877) 504-0233 toll free to arrange for a replacement.
Horizon Hobby, Inc. is sorry for this inconvenience and we are hopeful that our message will preclude any inadvertent use in your models.