The first RC-Monster Savage

[2FastSS4U]

Just looked at the Astro Flight Blinky balancer and it says that I can balance the packs after I finish charging the packs, this seems kind of odd to me. If I order this will I need 2 of them to balance both packs at the same time while charging and can I use my hyperion charger with this balancer?

Edit: One more thing, how long can I leave the packs uncharged for? Like if I want to go out and run my truck and run till the LVC kicks in, can I leave them dead for a while or do I have to recharge ASAP?