My experience with cheap, rechargeable things (flashlights especially) is that if you leave them plugged in , they will be charged, but the battery life will be killed inside of a year. You'll have 4 min of light when you need it, and if you charge it and leave it unplugged, it'll drain and you'll need to charge it before use.
Expensive rechargeable with good "smart" charging seem to get around this, but are expensive.
With the advent of cheap lithium CR123A and similar batteries that don't swell and corrode, hold power for years, and work decent in temperature extremes, I don't think the cheap rechargeable actually fill a role anymore. YMMV