Re: looking for good cordless phone sets

[Marc_F_Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx>]

On Thu, 22 Feb 2007 13:06:22 GMT, nobody@xxxxxxxxxxxx (Dave Houston) wrote in
message  <45dd93af.142535750@xxxxxxxxxxxxx>:

>"Robert Green" <ROBERT_GREEN1963@xxxxxxxxx> wrote:
>
>>I'm not sure this pack has anything but batteries.  Since it's still under
>>warranty, I am not slicing it open to see!  There's a thin plastic wrap
over
>>the three batteries and I can trace the wiring and the solder tabs with my
>>finger and I don't see (actually it's more like feeling) any other
>>components.  It takes 20 hours to charge so I am assuming it's very low
>>current trickle.
>
>Typically the thermistor and thermal switch are very small and not obvious -
>they may even be inline. Here's a Panasonic app note...
>
>http://www.panasonic.com/industrial/battery/oem/images/pdf/Panasonic_NiMH_ChargeMethods.pdf
>
>These might use the intermittent charge method shown on p13 of the handbook
>but even those probably have a thermal switch for liability reasons.
>

FWIW, none of the battery packs that came with the Panasonic KX-TG4000B
4-line base, Panasonic  KX-TGA400B  handset or the Panasonic KX-TG210-B phone
I mentioned in the original thread (" SOT: looking for good cordless phone
sets " -- BobbyG started an entirely new thread in his response) have any
thermistor or any other passive or active component in the battery packs.

The ones I have consist simply in five Ni-Cad, two Ni-MH , and three Ni-MH
AAA batteries (respectively) connected in series with welded stainless
conductors.

These are available from many different manufacturers. For example the
two-cell Panasonic HHR-P506 pack used in the Panasonic  KX-TGA400B  handset
is also available from Energizer (ER-P506), Uniden (BT-904), JASCO
(GE-TL26602), Lenmar (CBC206),  AT&T (17F) as well as generic 'brands" and
can e purchased for less than $5 + shipping or $8 shipping included.

The diagram that Dave references is used in three 3-wire battery packs that
use additional, often external electronics in conjunction with an on-board
thermistor which is used as a sensor and is not "inline". In large packs, (eg
laptop computers) the active electronics (an IC) may be in the battery packs
themselves. Years ago I saw battery packs with simple built-in  positive
temperature coefficient thermistors which were used in line (in series) as
over-temperature and(or) over-current protection, i.e., not as a sensing
element used with additional electronics. They may still be used. I dunno.
But these ain't them.

... Marc
Marc_F_Hult
www.ECOntrol.org