Is there a way to downgrade iOS's to the one before Apple start tanking you're battery as if it's dying?

Obviously with the admittance from Apple that they have been tanking people's batteries on the grounds of performance for older models. People with older models would be better on the IOS which maximises their battery life rather than makes tiny upgrades to the software and apps.

With that being the case, can we downgrade IOS to the one that better suited our models battery life & will there be a warning before future installations of updated iOS's that this latest update will seriously hamper your battery to the point that you can expect it to be dead before you leave the house of a morning?