Where if you have. Looking for nz sites there's thousands of them. Anyone bought a replacement battery, did you go aftermarket, or authentic? And anyone worth trusting or not?
I've found this simpower one: https://www.simpower.co.nz/product/home-garden/vacuum-cleaner-batteries/dyson-dc30-battery-14-8v-1500mah-li-ion-dyc300vx/
and Mr postitive: https://www.mrpositive.co.nz/dyson-dc30-aftermarket-vacum-cleaner-battery


