Are you referring to lipo batteries? If so, all of the lipo chargers with which I am familiar will shut off when the battery is charged.

As for your other question, lipos really don'y need a "tender" because their self-discharge rate is very low. A lipo charged today will be ready to fly even a couple of weeks from now.

If you are going to be storing a lipo for many weeks or months without using it, the battery should be stored with a partial charge, perhaps 60% of a full charge.

- Jeff