Coinspeaker TSLA Stock Down in Pre-Market, Musk: Tesla Battery Day Product Won’t Reach ‘Serious High Volume’ Until 2022According to the series of tweets by Musk, Tesla is largely going to focus on battery cell production, which should take maximum speed in two years.TSLA Stock Down in Pre-Market, Musk: Tesla Battery Day Product Won’t Reach ‘Serious High Volume’ Until 2022