Why would a DECT Panasonic cordless phone keep losing the wireless link?

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On Mon, 06 Jan 2014 22:28:25 -0800, Jeff Liebermann wrote:

That's a great suggestion Jeff.
Maybe these other DECT phones in the same house:
http://farm3.staticflickr.com/2873/11811729095_cafdd2467b_o.gif
Are causing the problem with this DECT phone:
http://farm4.staticflickr.com/3779/11811980883_f540a29bee_o.gif
It might also be the batteries, although you can see in the previous photo that they are fully charged - yet - I charged them today off the Panasonic base:
http://farm8.staticflickr.com/7341/11829684174_606aa41376_o.gif
And, strangely, when I ran the registration procedure, they showed up as being discharged! ?????????
http://farm8.staticflickr.com/7331/11829272305_f01a1c8679_o.gif
So that makes absolutely no sense. I chalk it up to "confused electronics" at this point - because I can't imagine what happened to make a fully charged battery indicate almost discharged.
Anyway, as a precaution, I ran the re-registration procedure, which is described on page 27 of this PDF: http://service.us.panasonic.com/OPERMANPDF/KXTG6431-MUL.PDF
This is a snapshot of the re-registration procedure:
http://farm8.staticflickr.com/7353/11829263895_ac761cd5cf_o.gif
Since the menus don't show up until *after* you run the procedure, I post below sequential screenshots so others who run the registration procedure can see the cause and effect on the phones:
Press LOCATOR on base 4 sec. Then press OK.
http://farm4.staticflickr.com/3708/11829267845_c9363aba09_o.gif
Call from Base:
http://farm8.staticflickr.com/7392/11829686934_e1799e3098_o.gif
Base regtr'ing
http://farm8.staticflickr.com/7331/11829272305_f01a1c8679_o.gif
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Danny D'Amico wrote:

One base and many handsets? Then logic tells me radio in the base unit is suspect. Or turn all handsets but one and try. By any chance checked the wall wart for the base unit? We have multi handsets but they are divided between two different base units. If some thing goes wrong easy to trouble-shoot
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On Mon, 06 Jan 2014 20:52:27 -0800, Jeff Liebermann wrote:

This is a good observation.
I picked up the Panasonic KX-TG6441 "Operating Instructions": http://service.us.panasonic.com/OPERMANPDF/KXTG6431-MUL.PDF
And the "Installation Manual" for the Panasonic KX-TG6441: http://service.us.panasonic.com/OPERMANPDF/KXTGA740B.PDF
The frequency range is *below* the 2.4GHz WiFi range: Frequency Range = 1.92 GHz to 1.93 GHz
And the claimed RF Transmission power is 115 mW (max.).
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You're spending too much time analyzing the problem, and not enough time testing.
Why hasn't someone suggested changing the WiFi channel? That's a great place to start testing.
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*The last time my Panasonic phone did that, I replaced the batteries with new ones. Problem went away. If yours are four years old I would think that it is time for a battery replacement. Home Depot has them and I think Wal-Mart does also.
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If they're 2.4 Ghz, wifi could be interfering too much.
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On Mon, 06 Jan 2014 23:24:45 -0700, Tony Hwang wrote:

This makes sense.
What I did today was I pulled the batteries out of the five handsets and pulled the power from the base, and let it sit that way all day.
http://farm6.staticflickr.com/5506/11829276385_b88f6d65c7_o.gif
Then, I performed the re-registration procedure as outlined on p27 of this PDF: http://service.us.panasonic.com/OPERMANPDF/KXTG6431-MUL.PDF
Here's just the Panasonic cordless phone re-registration procedure:
http://farm8.staticflickr.com/7353/11829263895_ac761cd5cf_o.gif
Hopefully, re-registering all five handsets may help with the problem of the Panasonic KX-TG6441 dropping calls after a while:
http://farm8.staticflickr.com/7331/11829272305_f01a1c8679_o.gif
I'll let you know what happens...
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On Wed, 8 Jan 2014 03:41:46 +0000 (UTC), Danny D'Amico

Ummm... was the phone designed to use NiMH or NiCd batteries? I'm too lazy to check.
NiMH batteries can be a problem due to high self discharge and possible overcharging. I suggest that you charge a few of the batteries in the phones for a day and then remove the batteries. Measure the voltage which should be about 1.2V when fully charged. Just let them sit outside the handset for at least 12 hrs (or more). Then measure the voltage again. 1.1V to 1.2V is fairly normal. 1.0V is borderline. Anything less than 1.0V is a problem. What you're measuring is the self-discharge rate, which tends to get worse as the batteries get older. It's particularly bad with NiMH which can lose 1% to 5% per day depending on temperature and age.
Besides dubious batteries, I'm beginning to suspect you may have multiple problems. Two independent but incompatible DECT systems, on the same frequency, are going to cause mutual interference. The reason the problem is intermittent is that both bases have be on the same channel in order to cause mutual interference. With 5 (US) channels to use, you're chances are 1 in 5 of having a collision. Unplug one base and see if the probleem goes away.
--
Jeff Liebermann snipped-for-privacy@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
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Jeff Liebermann wrote:

Part of the DECT standard is that a device listens before it transmits. If the channel is in use, it changes the channel. What happens when all channels are busy I have no idea.
What you describe was the problem with the old 2.4gHz cordless phones. They just picked a channel and transmitted on it. The later ones were spread spectrum, so as far as WiFi was concerned, it interfered on ALL of channels.
Or in plain English, when my upstairs neighbor's phone rang, my WiFi crashed.
DCT phones work the same way as DECT phones, but on the 2.4gHz or 5.8gHz band. Again, what they do when all channels are busy I do not know.
This is also why cell phones do not need to be licensed. They only transmit when asked to by a cell, which in most places is licensed.
If for example, you were to bring a 1900mHz GSM phone to Europe, or a 900/1800mHz EU GSM phone to the US, it won't start transmitting and interfere with whatever is using those frequencies.
Geoff.
--
Geoffrey S. Mendelson, N3OWJ/4X1GM/KBUH7245/KBUW5379


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On Wed, 08 Jan 2014 10:26:04 -0800, Jeff Liebermann wrote:

Hi Jeff, The batteries are the original, and, they're all Ni-MH batteries. I noticed a set (white paint) was of a different amperage, so, I reassembled all the sets with like-amperage batteries (to prevent reverse voltage situations).

I ran that from yesterday, Jeff, and they came back at 1.2 volts. So, I must tentatively conclude that the phone itself has a summative charging icon, where it might be "timed" in the charger, rather than checked at the battery.
All five handsets, with the same batteries that read nearly dead after charging, now read full. I haven't extensively tested yet, but, all seems well now (tentative assessment).

This might be the reason for the intermittence!
What I *should* do is buy a DECT system with 9 handsets instead of two DECT systems for a total of 9 handsets.
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On Fri, 10 Jan 2014 15:22:06 +0000 (UTC), Danny D'Amico

I don't believe it. The phones look at least 8 years old. If the NiMH batteries were that old and left on continuous charge, they should be nearly dead by now. I have a discharge tester (West Mtn Radio CBA-II) that can test them. Send me one cell and I'll run a test (time permitting).

Ok, the batteries are not totally dead.

Dunno. I've used a few Panasonic handsets around the house. The one with individual cells ate batteries about every 3-5 years.

Offhand, I would say a bad battery or charger connection. The chrome plated connections on both the handset and charger base don't make a reliable connection and must be cleaned carefully. Same with the internal battery contacts.

Just buying some additional handsets for your existing base might be a better and cheaper idea. The data sheets list the maximum number of handsets a base will accomodate. I know of one system with 12 handsets. This might help: <http://cordless-phones-review.toptenreviews.com/ Oops. Looks like Panasonic is limited to 6 handsets.
--
Jeff Liebermann snipped-for-privacy@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
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On Fri, 10 Jan 2014 09:17:11 -0800, Jeff Liebermann wrote:

Hi Jeff, The phones *are* old. I agree.
And, those yellow Ni-MH AAA batteries are the originals. So, I must have done the voltage test wrong.
Let me explain what I did, so we can see what I did wrong.
1. Here are four of the handsets, with full battery indicators:
http://farm3.staticflickr.com/2886/11882484886_4839174995_o.gif
2. Flipping them over, only two currently have original batteries:
http://farm4.staticflickr.com/3797/11882074284_ee4763c59f_o.gif
3. Opening one, I find the battery open-circuit voltage is 1.4VDC:
http://farm6.staticflickr.com/5498/11881637505_1ba94a31d5_o.gif
4. Likewise, the other battery is 1.4VDC, with no load on it:
http://farm3.staticflickr.com/2810/11881914203_f2b50e19ea_o.gif
5. Yet, putting them back, the phone now indicates a low battery:
http://farm4.staticflickr.com/3742/11882073034_b75d2d560e_o.gif
Conclusion? A freshly charged battery (hot off the phone cradle), reads good; but the phone charge indicator reads full at first, and then almost empty after merely removing and then replacing the batteries.
6. Similar voltages were found for the other handset batteries:
http://farm3.staticflickr.com/2824/11882072184_59ba294c4e_o.gif
http://farm8.staticflickr.com/7377/11881635665_24a4718078_o.gif
7. The replacement batteries read slightly higher voltages:
http://farm8.staticflickr.com/7392/11882071034_45f3c6231e_o.gif
8. Yet, all read low when immediately put back in the handset:
http://farm6.staticflickr.com/5482/11881635265_a2ba55592c_o.gif
I'm not sure what to make of this data ...
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On Tue, 07 Jan 2014 07:53:03 -0500, John Grabowski wrote:

This might actually be the problem!
After removing all the batteries and allowing the handsets and base to sit for about five hours today ...
http://farm6.staticflickr.com/5506/11829276385_b88f6d65c7_o.gif
When I put the batteries back, I noticed that all five handsets said to "Charge for 7 Hours" ...
http://farm8.staticflickr.com/7331/11829272305_f01a1c8679_o.gif
So, I put them all on a 3.5 hour charger:
http://farm8.staticflickr.com/7341/11829684174_606aa41376_o.gif
And, when I put them back into the phone, they *still* said to charge for 7 hours!
http://farm4.staticflickr.com/3756/11830061806_447da87566_o.gif
So, maybe it's that simple - that the Ni-MH batteries, which are a few years old, are bad.
One problem though, is that I put the new Ni-MH batteries that came with the charger in, after charging them on the charger, and the handsets *still* 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.
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On 1/7/2014 7:48 PM, Danny D'Amico wrote:

Since about zero percent of people are gonna do that, they might have concluded that a timer inside the device would determine that the device had charged all it could and the display was in terms of "do this" instead of any actual measurement, and be adequate to direct 99.9999% of users to perform the operation.
Some people are "overthinkers" ;-) Hmmm...I resemble that remark.
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On Tue, 07 Jan 2014 20:03:55 -0800, mike wrote:

That might be the case Mike, because I know two things.
The batteries were showing fully charged initially:
http://farm4.staticflickr.com/3779/11811980883_f540a29bee_o.gif
Then, I removed them and let the phone sit for a few hours:
http://farm6.staticflickr.com/5506/11829276385_b88f6d65c7_o.gif
When I then ran my first re-registration procedure, I was surprised to see that all five phones suddenly showed low battery indications:
http://farm8.staticflickr.com/7331/11829272305_f01a1c8679_o.gif
That made no sense because pulling the batteries and letting them sit disconnected for a few hours couldn't possibly have discharged them from full to near zero. But it was easy enough to charge them independently on a Ni-MH charger:
http://farm8.staticflickr.com/7341/11829684174_606aa41376_o.gif
Yet, I was again very surprised to see, after 3.5 hours on the charger (the lights stop blinking on the charger to indicate full charge) that, back in the handsets, they *still* said they were low on charge!
http://farm4.staticflickr.com/3756/11830061806_447da87566_o.gif
Something doesn't add up - but all five handsets acted the same way, even with the four new batteries from the charger put into two of the handsets.
All five phones are now in their respective holders, and, I just checked the charge, and they went from one bar to three bars, so, that's just weird.
It's almost as if they'll only charge from their Panasonic holders, and not from a separate non-Panasonic charger. But, that makes no sense - so - I really don't know what to make of this inconsistent data other than to ignore it.
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On 01/07/2014 10:48 PM, Danny D'Amico wrote:

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
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Tony Matt wrote:

Maybe I am dumb or simple minded. Manual says charge 7 hours B4 using. I just left it over night out of box. Ever since they all have been reliably working. At home and at the store.
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wrote:

charge it is possible for the remote to loose connection to the base on SOME Panasonic phones. Mine are KXT5433 5.8ghz units and it has happened to me. Don't know about DECT
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On Tue, 14 Jan 2014 23:57:25 -0500, Tony Matt wrote:

Thanks for confirming.
It took me a while (mostly at Jeff's insistance) to test the batteries, which, turned out (surprisingly) to be fine, even though the phone said they needed charging, right after the phone said they were fine.
Go figure. SO far, it has worked out ok, so, I think the re-registration process was what fixed it (I think).
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Danny D'Amico wrote:

Panasonic implemented mandatory >7 hour initial charge to ensure long battery life. On any rechargeable batteries proper initial charge is very important. It is not whether battery is charged or not. It is just so. You are obliged to make sure at least 7 hour charging time. Usually owners manual does not explain things in full. Panasonic CL phones in my house is almost 10 years old. None yet needs new battery.
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