Instruct: Classify Amazon reviews into positive or negative sentiment
Query: two batteries, still no staying power

Black & Decker NST2018 18-VOLT CORDLESS GRASS HOG TRIMMER.The auto string feed is great, now if they can get some "staying power" from the two batteries! Cannot trim front or back yard before both batteries need charging. The re-charging time for each battery makes the trimming operation a two day affair. Now have three batteries, but re-charge time is still a hold-up.