Semi-used AA Duracells cost a fraction of what a new 8-pack of coppertops would normally set you back. They’re a mere $3.25 for 8 batteries on American Science & Surplus, compared to $14.99 for new 8 pack on Amazon. The low-self-discharge (LSD, baby!) batteries are awesome. They are ready to rock months after they were last charged. Their actual capacities are a bit less than the best non-LSD batteries, but the LSD factor outweighs the 5% lower capacity.”]
Source: https://gizmodo.com/buy-these-cheap-coppertops-pulled-from-unsafe-toys-5803269