Due to the self-discharge, the batteries can be empty after a few months. This disadvantage is significantly reduced by special NiMH batteries with low self-discharge, Low Self-Discharge (LSD).
LSD batteries are pre-charged NiMH batteries, also known as Ready to Use( RTU). They are nickel-metal hydride based and have a much improved separator and positive electrode. They are said to still have about 80% of their energy after one year of storage, at least twice as much as conventional NiMH batteries. However, the rated capacity is lower than comparable conventional NiMH batteries.