I am dealing with a KX-TG6443T (with KX-TGA461 handsets). It's a 9-y.o. Dect6.0 phone (which is nice for small offices and homes).
One (most used) handset (#1) suddenly started complaining about fully discharged battery after just a few minutes of talk on its speakerphone. I wouldn't be surprised that the batteries became old, but...
When the batteries were swapped from the seldom-used handset (#3) (where they were working fine), - the same story repeated. (Each time the handsets are fully recharged in their charging cradles for several hours.) After the batteries were swapped back, they were showing the same short talk time back in handset #3 also.
I installed brand-new rechargeable batteries in one of these handsets (they are by Duracell, not OEM, but I assume that shouldn't matter). And they show the same short use time.
The strange thing is that when I take the battery out of the phone and measure its voltage, it shows a very high value, 1.46 V even after just a few minutes (5-10) after charging from "Empty", when the phone asks to charge it for 8 hrs, and when the indicator still shows the battery charge being far below even 1/2.
The fully charged battery shows 1.49 V or so.
This is a bit weird, because when I am charging this type of rechargeable batteries using my La Crosse charger, if I am using slow (200 mA) charging, it stops when reaches 1.36 - 1.39 V. If I am using higher-current mode (1000 mA), then it does go up to 1.45-1.47 V. I seldom see anything close to 1.49 V.
On one hand it suggests that the phone itself might be using rather high current for quick charging.
On another hand, it raises some questions about what might be wrong with this phone set:
1. Are the Panasonic batteries used here significantly different (The original model HHR-65AAABU - 630 mAh)?
2. Could something have happened to all the handsets -- I doubt that all of them broke at the same time and the same way.
3. Could something have happened to the charging cradles? -- as above, - this is unlikely.
4. Could something have happened to the base unit that somehow is driving the energy consumption up? (This was proposed by the "Live chat support" on Panasonic support site whose only explanation of how it can do that was a cryptic statement: "because it all runs off the base internal service".
While I can imagine that the base can start constantly driving handset's transmission power up, I am not sure how realistic that is.
I am trying to figure out which next step would make sense:
1. Buying OEM (Panasonic) batteries (but unless they are really different, why spend extra ~$14?)
2. Buying a brand new phone (it's a $100+ purchase, and having recently replaced several pieces of equipment (including some appliances) and anticipating a few more, we are a bit cautious with the budget). Besides, I am a bit reluctant to throw away things that are still working if there is a simple fix.
Unfortunately, this family of phones is discontinued in 2014, so we don't have an option of buying just a new base (or even borrowing one).
Does anybody know these systems well enough to speculate on what is the likely or possible culprit(s) that would fit the symptoms described above?