What is the self discharge rate of a NiMH battery? : eBay Guides

The rate of self discharge for any battery depends on the temperature at which it's stored. Stored at 70 degrees F (20 C) NiMH batteries will lose up to 40% of their charge within a month. If they are stored at a higher temperature, they will self discharge at an even higher rate. Stored at a lower temperature they self discharge at a lower rate.