Would the "fast charge" be harmful to lipo batteries?
If the "storage" mode would automatically discharge to appropriate storage voltage, when would you use the "discharge" mode? Thanks.
Yes, fast charge can be harmful to LiPo packs. ALWAYS balance charge them.
Discharge mode is used when you want to bring the packs down below storage voltage. Not really needed for LiPo, but this is needed for other chemistries. I occasionally (once a year) discharge my LiPo packs down to 3.2v/cell and then fully charge them to check capacity.
Whatever it is I just typed... could be wrong.