4s lipo

Hey, So I bought a new 4s Lipo by Tattu, and I've got batteries from them before. But as you can guess from the title it arrived with a dead cell. The drone still flew but at a low power obviously. I didn't realise until I went to charge it that one cell was at 0v. Does anyone know how to...

Hi all. Longtime Flitetest watcher, First time builder and poster. I've ordered an Electrohub Y6 from the Flitetest store with the Hex D power pack. I also ordered a few 4s batteries to go with it. The info on the store says it can run on 4s with "Smaller Props", but what size should I be...