Power tool NiCd battery charge circuit?

[DaveC]

Panasonic power screwdriver, 2.4v battery consists of 2 "C" (?)-sized cells
(0.88 in D x 1.77 in L) in series. Third terminal in pack connects a series
resistor (340 ohm) and a glass device (not a diode) to minus terminal.

I presume that the voltage at this terminal changes with temperature, ie.
sensing the battery's state of charge. Am I correct? Is this device a
thermistor (no markings)? Are these "C" cells, or proprietary size?

Thanks,
--
DaveC
me@privacy.net
This is an invalid return address
Please reply in the news group

 

[DaveC]

On Tue, 23 Dec 2003 7:13:01 -0800, DaveC wrote
(in message <0001HW.BC0D9B7D00936655F0080600@news.individual.net&gt:

Panasonic power screwdriver, 2.4v battery consists of 2 "C" (?)-sized cells
(0.88 in D x 1.77 in L) in series. Third

These are smaller than C cells. What are these?

Thanks,
--
DaveC
me@privacy.net
This is an invalid return address
Please reply in the news group

 

[Watson A.Name - "Watt Sun]

In article <0001HW.BC0D9B7D00936655F0080600@news.individual.net>,
me@privacy.net mentioned...

Panasonic power screwdriver, 2.4v battery consists of 2 "C" (?)-sized cells
(0.88 in D x 1.77 in L) in series. Third terminal in pack connects a series
resistor (340 ohm) and a glass device (not a diode) to minus terminal.

I presume that the voltage at this terminal changes with temperature, ie.
sensing the battery's state of charge. Am I correct? Is this device a
thermistor (no markings)? Are these "C" cells, or proprietary size?

Seem shorter than a normal C cell, probably called a 2/3 C cell.
Usually the charger is just a rectifier on the secondary of a wall
wart, and some form of current limiting. If you charge Ni-Cds at 10%
or less of capacity, they don't seem to have a problem with continuous
charging in a cradle.

Thanks,

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@

 

[Jerry G.]

There is normally a temperature sensing protection against excessive
overheating of the batteries. This is not a level of charge sensor. These
batteries are charged until they equalize with the charge source, and then
float.

If the batteries have a few years on them, they will have to be replaced. I
found that after a few years, or a few hundred charges, they start to not
hold their charge very well.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"DaveC" <me@privacy.net> wrote in message
news:0001HW.BC0D9B7D00936655F0080600@news.individual.net...
Panasonic power screwdriver, 2.4v battery consists of 2 "C" (?)-sized cells
(0.88 in D x 1.77 in L) in series. Third terminal in pack connects a series
resistor (340 ohm) and a glass device (not a diode) to minus terminal.

I presume that the voltage at this terminal changes with temperature, ie.
sensing the battery's state of charge. Am I correct? Is this device a
thermistor (no markings)? Are these "C" cells, or proprietary size?

Thanks,
--
DaveC
me@privacy.net
This is an invalid return address
Please reply in the news group

 

[William P.N. Smith]

"Jerry G." <jerryg50@hotmail.com> wrote:

There is normally a temperature sensing protection against excessive
overheating of the batteries. This is not a level of charge sensor. These
batteries are charged until they equalize with the charge source, and then
float.

Unless it's a high-rate or quick charger, in which case the battery
heating is used as a quick and dirty end-of-charge indicator...

--
William Smith
ComputerSmiths Consulting, Inc. www.compusmiths.com

 

[DaveC]

On Tue, 23 Dec 2003 10:25:30 -0800, William P.N. Smith wrote
(in message <f42huv4iaft762s052pits1pjk3qi5ppl9@4ax.com&gt:

"Jerry G." <jerryg50@hotmail.com> wrote:

There is normally a temperature sensing protection against excessive
overheating of the batteries. This is not a level of charge sensor. These
batteries are charged until they equalize with the charge source, and then
float.

Unless it's a high-rate or quick charger, in which case the battery
heating is used as a quick and dirty end-of-charge indicator...

Which I suspect is the case.

Economics are edging out the value of rebuilding this pack. Sub-C cells are
$5 and change, plus the labor of adding tabs (spot welding) and
"conditioning" of the cells at the local battery outlet. $17. New replacement
pack is $25. Hmm...
--
DaveC
me@privacy.net
This is an invalid return address
Please reply in the news group

 

[James Sweet]

"DaveC" <me@privacy.net> wrote in message
news:0001HW.BC0D9B7D00936655F0080600@news.individual.net...

Panasonic power screwdriver, 2.4v battery consists of 2 "C" (?)-sized
cells
(0.88 in D x 1.77 in L) in series. Third terminal in pack connects a
series
resistor (340 ohm) and a glass device (not a diode) to minus terminal.

I presume that the voltage at this terminal changes with temperature, ie.
sensing the battery's state of charge. Am I correct? Is this device a
thermistor (no markings)? Are these "C" cells, or proprietary size?

Thanks,
--
DaveC
me@privacy.net
This is an invalid return address
Please reply in the news group

Sounds like a standard sub-C cell, most rechargeable stuff uses them.

 

[Sam Goldwasser]

DaveC <me@privacy.net> writes:

On Tue, 23 Dec 2003 7:13:01 -0800, DaveC wrote
(in message <0001HW.BC0D9B7D00936655F0080600@news.individual.net&gt:

Panasonic power screwdriver, 2.4v battery consists of 2 "C" (?)-sized
cells (0.88 in D x 1.77 in L) in series. Third

These are smaller than C cells. What are these?

Look in any electronics distributor's catalog for batteries. There
are all sorts of different size versions of C cells and generally
available. Sub-C, 2/3 C, 1/3 C, etc.

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work. To
contact me, please use the feedback form on the S.E.R FAQ Web sites.

 

[Sam Goldwasser]

DaveC <me@privacy.net> writes:

Unless it's a high-rate or quick charger, in which case the battery
heating is used as a quick and dirty end-of-charge indicator...

Which I suspect is the case.

Economics are edging out the value of rebuilding this pack. Sub-C cells are
$5 and change, plus the labor of adding tabs (spot welding) and
"conditioning" of the cells at the local battery outlet. $17. New
replacement pack is $25. Hmm...

Where are you buying cells? Last time it was around $2 a cell and I suspect
now with a quick search on the Web, you'd find them for $1 or less with tabs.

Conditioning is probably a waste.

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work. To
contact me, please use the feedback form on the S.E.R FAQ Web sites.

 

[Watson A.Name - "Watt Sun]

In article <bs9sl0$sqm$1@news.eusc.inter.net>, jerryg50@hotmail.com
mentioned...

There is normally a temperature sensing protection against excessive
overheating of the batteries. This is not a level of charge sensor. These
batteries are charged until they equalize with the charge source, and then
float.

If the batteries have a few years on them, they will have to be replaced. I
found that after a few years, or a few hundred charges, they start to not
hold their charge very well.

Very true. Trouble is, this also happens wiht he Lithium Ion
batteries we have at work in the Dell Laptops. And after a year of
constant use every day, POOF! There goes a hundred and fifty bucks
for a new Dell battery.

--

Greetings,

Jerry Greenberg GLG Technologies GLG

"DaveC" <me@privacy.net> wrote in message
news:0001HW.BC0D9B7D00936655F0080600@news.individual.net...
Panasonic power screwdriver, 2.4v battery consists of 2 "C" (?)-sized cells
(0.88 in D x 1.77 in L) in series. Third terminal in pack connects a series
resistor (340 ohm) and a glass device (not a diode) to minus terminal.

I presume that the voltage at this terminal changes with temperature, ie.
sensing the battery's state of charge. Am I correct? Is this device a
thermistor (no markings)? Are these "C" cells, or proprietary size?

Thanks,

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@

 

[Watson A.Name - "Watt Sun]

In article <f42huv4iaft762s052pits1pjk3qi5ppl9@4ax.com>, William P.N.
Smith <> mentioned...

"Jerry G." <jerryg50@hotmail.com> wrote:
There is normally a temperature sensing protection against excessive
overheating of the batteries. This is not a level of charge sensor. These
batteries are charged until they equalize with the charge source, and then
float.

Unless it's a high-rate or quick charger, in which case the battery
heating is used as a quick and dirty end-of-charge indicator...

Yesterday I stopped by Fry's and checked out their batteries. Rayovac
now is selling a "15 minute Charger" with a couple batteries. It says
something about "charging system", so my guess is that the charger
only works that quick with their special cells.

I bet they get pretty hot!


--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@