On 01/07/2014 10:48 PM, Danny D'Amico wrote:
When I put the batteries back, I noticed that all five handsets said to
"Charge for 7 Hours" ...
[...]
So, something fishy is going on ... with the charge message on the
handsets ... but I don't know what yet.

Been there, done that, should have posted sooner. These/some Panasonic
cordless handsets display a "Charge for 7 hours" message (and a single
bar on the battery gauge) whenever batteries are installed, regardless
of the state-of-charge.

Details:

Last spring I attempted to set up a used KX-TG9341S system and got this
message on all of the handsets. Old batteries, new batteries, Panasonic
batteries, externally charged batteries, didn't matter (other than
alkaline cells, which it detected: "Wrong battery type"). Measured
voltages, currents, took apart a handset to look for damaged components,
double checked that full battery voltage was actually getting to the
PCB. Googled it, read a bunch of head-scratching, generic battery
advice, and speculation. Got frustrated and moved on to other projects.

A few months later I saw some of the Panasonic NiMH cells at the local
recycling center and decided to take another run at it. I charged
(externally) all of the cells and tested them. Then I got another idea
- I don't normally use AAA NiMH cells, but use lots of AA cells, so
jumpered over a pair of known-good, freshly charged AA cells to the
battery terminals of one of the handsets. Still got the 7 hour message.
That seals it - it's not the batteries. I picked the best six
Panasonic cells, let the handsets go through their 7 hour charge cycle,
and have been using the system ever since.

Panasonic apparently decided to override the charge sense/termination
circuitry with the 7 hour timer when batteries are installed in order to
reduce product returns (from customers who neglect to read the fine
manual and discover that their brand-new handsets and batteries don't
work right away). I did find some weak cells over time, but that's
unrelated to the 7 hour message.

Recommendations:

1. If you put charged cells into the handset, ignore the message and
leave the handset out of the charger for a few days (while using it, of
course). Otherwise, the batteries will be overcharged by the forced
7-hour 'initial' charge.

2. Test for good cells in the handset by trying the speaker phone
option. A weak cell will result in a power cycle (no audio, blank
display, then display with no backlight). If both cells are weak, it
will power cycle when the backlight comes on (i.e. whenever a button is
pressed). Check the cells under load with a meter to determine if one
cell has dropped out, or they are both at low charge. Keep pairs of
cells matched wrt state-of-charge.

3. Look elsewhere for the solution to your link issue.

Good Luck,
Tony Matt