Rechargeable Batteries, Phone and Flashlight

My father has taken to removing his telephones off the hook to keep them from overcharging or from developing "memory" problems. I've tried to explain to him that this is counterproductive and that he may actually be reducing the lifespans of his batteries by sucking the battery power when they're already low.

He's got about ten phones throughout the house and it's not a huge house. I'm just getting tired of picking up phones that aren't set in their charger stations, then getting "beeps" every 15 seconds about five minutes into a call. He won't take my word for it, so I thought I'd ask here to see if someone could explain how things have changed from the old ni-cad phones of two decades ago.

If his cordless phones have NiCD cells in them, then they can be left on the base stations all the time if you want to have as much of a charge in the phone when you pick it up as possible. But if each phone is used very rarely, the cells will live a longer "shelf-life" off the charger rather than on the charger, as most cordless phones do just dummy-trickle charge the cells all the time, slowly baking them. NiCD is tolerant to this charging method, but does develop an increase in self-discharge and slowly reducing capacity over the years when "plugged in" like that all the time.

There is merit to leaving them off the hook some of the time to give the cells a rest from charging. But whether it's worth the hassle of having a bunch of mostly-dead phones (from self-discharge) lying around is another question....

Are all of his extra phones part of the same "set?" Like- do they all communicate with a primary base station? If they do, then he could save his batteries by putting a timer on all the other little charging stations, that comes on in the middle of the night for like 8 hours. That way the cells would only be charging for 8 of every 24 hours. That should keep them topped off, while at the same time, probably nearly doubling the life of the batteries within.

Then the question is- what's cheaper, a timer, or a new NiCD pack from online somewhere, lol.

It has been my experience that a new set of 4 new cordless phones with chargers cost around $100 on average and last many years living on the charger. Some batteries in one of the units go out sooner than others. If you don't already own them, buying 4 plug in timers to limit each phones time on the charger, one for each phone, can cost anywhere from $20 to $50. Replacement batteries cost $6 to $15 dollars apiece as well. It also seems that after a number of years some of the number keys stick and don't release well. From a purely economical standpoint you may be able to extend the life of these units with some regular care and attention.

I find that very few people I know pay any attention to this type of maintenance and find it much simpler to just use them daily and get a whole new set of phones later when problems arise. You should get a good five years out of the set with little to no problems. It seems the same strategy is followed with cell phones.