Discussion:
Panasonic cordless phone
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pinnerite
2024-09-05 10:20:49 UTC
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Panasonic cordless phones all appear to come with their own mains-charger plug.
To reduce clutter I would like to power mine from a USB charger hub.
Has anyone dived into this at some time?
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Peter Johnson
2024-09-05 11:28:20 UTC
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Post by pinnerite
Panasonic cordless phones all appear to come with their own mains-charger plug.
To reduce clutter I would like to power mine from a USB charger hub.
Has anyone dived into this at some time?
What's the Pansonic voltage? You'll only get 5v max out of USB and
you'll need to check that your hub can give you that.
pinnerite
2024-09-05 13:04:56 UTC
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On Thu, 05 Sep 2024 12:28:20 +0100
Post by Peter Johnson
Post by pinnerite
Panasonic cordless phones all appear to come with their own mains-charger plug.
To reduce clutter I would like to power mine from a USB charger hub.
Has anyone dived into this at some time?
What's the Pansonic voltage? You'll only get 5v max out of USB and
you'll need to check that your hub can give you that.
The base says it delivers 4.8v at 150mA. I reckon that there's a match
there. I need to replace the lead to the power unit with one with a USB
plug at one end and the RJ type plug that plugs into the base unit on
the other. It would help if I could identify which wire went where.
--
Linux Mint 21.3 kernel version 5.15.0-119-generic Cinnamon 6.0.4
AMD Ryzen 7 7700, Radeon RX 6600, 32GB DDR5, 1TB SSD, 2TB Barracuda
fred
2024-09-05 13:13:46 UTC
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Post by pinnerite
On Thu, 05 Sep 2024 12:28:20 +0100
Post by Peter Johnson
Post by pinnerite
Panasonic cordless phones all appear to come with their own
mains-charger plug. To reduce clutter I would like to power mine
from a USB charger hub. Has anyone dived into this at some time?
What's the Pansonic voltage? You'll only get 5v max out of USB and
you'll need to check that your hub can give you that.
The base says it delivers 4.8v at 150mA. I reckon that there's a match
there. I need to replace the lead to the power unit with one with a
USB plug at one end and the RJ type plug that plugs into the base unit
on the other. It would help if I could identify which wire went where.
Multimeters are super cheap these days so no excuse for not having one in
the toolkit. You'll suss your connections in no time.
pinnerite
2024-09-05 13:32:21 UTC
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On Thu, 05 Sep 2024 13:13:46 GMT
Post by fred
Post by pinnerite
On Thu, 05 Sep 2024 12:28:20 +0100
Post by Peter Johnson
Post by pinnerite
Panasonic cordless phones all appear to come with their own
mains-charger plug. To reduce clutter I would like to power mine
from a USB charger hub. Has anyone dived into this at some time?
What's the Pansonic voltage? You'll only get 5v max out of USB and
you'll need to check that your hub can give you that.
The base says it delivers 4.8v at 150mA. I reckon that there's a match
there. I need to replace the lead to the power unit with one with a
USB plug at one end and the RJ type plug that plugs into the base unit
on the other. It would help if I could identify which wire went where.
Multimeters are super cheap these days so no excuse for not having one in
the toolkit. You'll suss your connections in no time.
I have two multimeters but without taking my feet off the bottom and
cutting the existing lead, I will not be able to use the meters. I am
not that confident.
--
Linux Mint 21.3 kernel version 5.15.0-119-generic Cinnamon 6.0.4
AMD Ryzen 7 7700, Radeon RX 6600, 32GB DDR5, 1TB SSD, 2TB Barracuda
Theo
2024-09-05 13:56:48 UTC
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Post by pinnerite
I have two multimeters but without taking my feet off the bottom and
cutting the existing lead, I will not be able to use the meters. I am
not that confident.
If you wrap some fine bits of wire around each of the multimeter probes, you
should be able to get at the gold contacts on the RJ plug, even if the
probes themselves are too fat to reach them.

Or buy a matching socket and use that to probe it out with the power cable
plugged in.

Since it's low voltage / current there's not much damage you can do if you
accidentally short it out.

Theo
fred
2024-09-05 13:58:42 UTC
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Post by pinnerite
On Thu, 05 Sep 2024 13:13:46 GMT
Post by fred
Post by pinnerite
On Thu, 05 Sep 2024 12:28:20 +0100
Post by Peter Johnson
Post by pinnerite
Panasonic cordless phones all appear to come with their own
mains-charger plug. To reduce clutter I would like to power mine
from a USB charger hub. Has anyone dived into this at some time?
What's the Pansonic voltage? You'll only get 5v max out of USB and
you'll need to check that your hub can give you that.
The base says it delivers 4.8v at 150mA. I reckon that there's a
match there. I need to replace the lead to the power unit with one
with a USB plug at one end and the RJ type plug that plugs into the
base unit on the other. It would help if I could identify which
wire went where.
Multimeters are super cheap these days so no excuse for not having
one in the toolkit. You'll suss your connections in no time.
I have two multimeters but without taking my feet off the bottom and
cutting the existing lead, I will not be able to use the meters. I am
not that confident.
You'll need to dismantle bases to to gain access to terminals for USB
power connections so should be able to determine at least polarity from
there with the multimeter. Dismantling should be straightforward, I have
always found them to be screwed rather than glued. Inside the base is the
place to do a proper job/connection but expect to make good soldered
connections or to await trouble later on. If you don't want to do that
then you'll be using a scalpel to disect the base cable and following
that you can use a sharp object to pierce the inners to determine
polarity, voltage and so on and then make external connections but that
will be a bit of a bodge.
Paul
2024-09-06 03:09:06 UTC
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Post by pinnerite
On Thu, 05 Sep 2024 13:13:46 GMT
Post by fred
Post by pinnerite
On Thu, 05 Sep 2024 12:28:20 +0100
Post by Peter Johnson
Post by pinnerite
Panasonic cordless phones all appear to come with their own
mains-charger plug. To reduce clutter I would like to power mine
from a USB charger hub. Has anyone dived into this at some time?
What's the Pansonic voltage? You'll only get 5v max out of USB and
you'll need to check that your hub can give you that.
The base says it delivers 4.8v at 150mA. I reckon that there's a match
there. I need to replace the lead to the power unit with one with a
USB plug at one end and the RJ type plug that plugs into the base unit
on the other. It would help if I could identify which wire went where.
Multimeters are super cheap these days so no excuse for not having one in
the toolkit. You'll suss your connections in no time.
I have two multimeters but without taking my feet off the bottom and
cutting the existing lead, I will not be able to use the meters. I am
not that confident.
That's the spirit.

The cordless phone has four NiMH batteries in it. You didn't state
the model number, so this is just a guess.

The base is a *battery charger*, not a "power supply" as such.

battery chargers should cut off the charging current, when
the battery is full. The charger has to recognize the "endpoint"
of the charging process. Lithium Cobalt chargers are an example
of a very good charging method -- it has to be good, or there
will be a fire.

Other chemistries on the other hand, can work well
*if* the batteries are Fast Charge type and you can ram a lot of
current into them. The enhanced current makes the endpoint visible.
At lower currents, the endpoint is not distinct, and the other
control methods are "crap". This leads to premature battery failure
due to abuse. It's hard to design a smart charger for NiCD or NiMH,
unless the cell type is Fast Charge. And certain aspects of the
chemistries, don't always allow that (you cannot make 8Ah D cell NiCD
as a Fast Charger type, because the number of amperes that would flow
is prohibitive and the materials will not take such treatment).

https://batteryuniversity.com/article/bu-408-charging-nickel-metal-hydride

You're not fooling with a power supply. This is a
case of a "something else" circuit.

And I absolutely *hate* engineers who do this. The God damn
charger should be *inside* the hand unit. Only a voltage source
should drive the phone, such as a 19V wall adapter. If the
charger solution is self-contained, the input voltage can be
wide range, and you can use a number of power sources for
substitution purposes.

Putting the battery terminals on the bottom of the device
and inviting people to connect 5V voltage sources where they
do not belong, is so so *wrong* . They should not do this.

it's as bad as my fucking Black and Decker battery screwdriver,
where the fools idea of a charging circuit was a single resistor.
This uses the observation that NiCD can be successfully abused
by trickle charging it... forever. Well, I have some bad news
for the idiots. When you do that, the electrolyte blows past the
pressure relief value and coats everything in the vicinity with
a chemical which is a strong base. As you buy one replacement
battery pack after another, it ruins them. This means (of course),
I hardly ever got to use my Blackened Decker screwdriver, because
of the shortcut taken on charging. Your Panny product may not be
that much better...

Summary: Do some extra checking with regard to circuit type before
making the wrong kind of substitution. There be dragons...
I can hear hissing, and the smell of napalm fills the air...

Paul
Theo
2024-09-06 08:28:59 UTC
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Post by Paul
That's the spirit.
The cordless phone has four NiMH batteries in it. You didn't state
the model number, so this is just a guess.
The base is a *battery charger*, not a "power supply" as such.
battery chargers should cut off the charging current, when
the battery is full. The charger has to recognize the "endpoint"
of the charging process. Lithium Cobalt chargers are an example
of a very good charging method -- it has to be good, or there
will be a fire.
Often battery charger bricks are as you say, constant-current (during charging)
and then constant-voltage (at top of charge) - CC/CV devices.

But this base also talks to the phone network, ie it's not a pure charger it
has some other current draw as well. This would mess with the CC part.

Also this is marked 4.8v, which is only middle of charge for 4x NiMH cells. Top
of charge is 1.55v per cell - I suppose ToC for 3 cells would be 4.65v which
is not a mile off 4.8v.

That said, I have an ebike charger for a 20S NiMH pack marked 24V 2A - this
must be a lie because ToC should be 1.55*20 = 31v. I should measure it.

But the point stands that current limiting in the brick may be needed. The
answer to that is to put some flat batteries in the handset and see if the
output from the brick remains 4.8v or dips based on the cell voltage.

Theo
Adrian Caspersz
2024-09-05 12:05:57 UTC
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Post by pinnerite
Panasonic cordless phones all appear to come with their own mains-charger plug.
To reduce clutter I would like to power mine from a USB charger hub.
Has anyone dived into this at some time?
I've got a few of them.

One here has a power adaptor PQLV219E that has stated on it, output 6.5V
500mA dc. Another has an power adaptor PNLV233E, output 4.8V 160mA dc.

The voltage is also written on the cradle, which has a warning only to
use the specified adaptor.

The adaptors are small, personally I'm not fussed to DIY an alternative.
Doubt many would - these things are left on 24/7 charging batteries and
may be connected to the phone network (if used for the main station) and
have isolation components for such (i guess?)
--
Adrian C
Jeff Layman
2024-09-07 08:23:21 UTC
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Post by Adrian Caspersz
Post by pinnerite
Panasonic cordless phones all appear to come with their own mains-charger plug.
To reduce clutter I would like to power mine from a USB charger hub.
Has anyone dived into this at some time?
I've got a few of them.
One here has a power adaptor PQLV219E that has stated on it, output 6.5V
500mA dc. Another has an power adaptor PNLV233E, output 4.8V 160mA dc.
The voltage is also written on the cradle, which has a warning only to
use the specified adaptor.
My Panasonic's base unit has 5.5V 500mA on the bottom, as has the
wallwart powering it. The secondary unit also has 5.5V 500mA on its
base (I can't get to the wallwart to see what's on it, but I suspect
it's the same one as the base unit uses). The phones themselves uses two
AAA NiMH batteries.
Post by Adrian Caspersz
The adaptors are small, personally I'm not fussed to DIY an alternative.
Doubt many would - these things are left on 24/7 charging batteries and
may be connected to the phone network (if used for the main station) and
have isolation components for such (i guess?)
Agreed. My phone is now over 11 years old and has no problem with a call
lasting an hour. IIABDFI...
--
Jeff
Theo
2024-09-05 12:17:28 UTC
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Post by pinnerite
Panasonic cordless phones all appear to come with their own mains-charger plug.
To reduce clutter I would like to power mine from a USB charger hub.
Has anyone dived into this at some time?
It doesn't happen to have a data link socket does it? I have a Gigaset
SL400 which has a mini USB socket for exchanging contacts or whatever.
Turns out it'll charge just fine from USB.

Theo
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