I have a small amount of Ni-Mh rechargeable batteries, which I leave charged to pop into whatever device happens to go flat.
However recently I have noticed the 'charged' batteries are flat. I think possibly the charger might be bung, but I suspect not.
Do NiMh batteries retain their charge properly out of a device? Is it better practice to leave them uncharged, then charge them on demand? I don't really like doing this, as they take ages to charge.