<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">I see other folks have cautioned that you must tap across the correct two cells and ONLY the correct two. I’d like to add that you better use a regulator between 2s backup and the receiver if you want the 5s pack to be the primary and the 2s the backup if you do use a backup, and you really should. The voltage on the bottom two cells of the 5s can get quite low near the end of a long flight when they are under a high fluctuating load, and the noise level can be quite high causing erratic receiver behavior. And by the way, if you put a regulator on both, you can set it up for a six volt (LV) setup.<div class=""><br class=""></div><div class="">Now if you are running an ESC with a BEC you can connect it directly to the receiver and also connect the 2s backup pack directly to the receiver (through an on/off switch). I set the BEC to 8.0 volts and the system keeps the backup charged to 8.0 so it should last for years. See the wiring diagram for my Acuracy Pipe.</div><div class=""><br class=""></div><div class=""></div></body></html>