Is it ok to leave a cordless fone on the charger? I returned 3 V Teck fone s only lasted 3 days?

Answer 1

In general, yes. Most phones and other rechargeable devices will simply stop charging once they reach the proper voltage.

Most companies will design devices so that they can be forgotten on the charger these days. With all the distractions of life, it isn't unusual for a phone, drill, or whatever to stay on the charger for days or weeks.