One of the battery packs on a cordless screwdriver has just started
playing up. Put it in the tool and nothing happens. Put a meter
across the terminals and the voltage fluctuates rapidly between zero
and just above the nominal value. (Other pack works fine and shows
steady, correct value on the meter.) I've taken it apart and all the
contacts look fine. Can anyone suggest what's wrong with it?

"mike" wrote in message
...
One of the battery packs on a cordless screwdriver has just started
playing up. Put it in the tool and nothing happens. Put a meter
across the terminals and the voltage fluctuates rapidly between zero
and just above the nominal value. (Other pack works fine and shows
steady, correct value on the meter.) I've taken it apart and all the
contacts look fine. Can anyone suggest what's wrong with it?

"She's dead Jim"
" It was life, but not as we know it"

In article 3007ab9c-e345-4687-a7bf-392ce6fdceb0
@j9g2000vbp.googlegroups.com, "mike" wrote:
One of the battery packs on a cordless screwdriver has just started
playing up. Put it in the tool and nothing happens. Put a meter
across the terminals and the voltage fluctuates rapidly between zero
and just above the nominal value. (Other pack works fine and shows
steady, correct value on the meter.) I've taken it apart and all the
contacts look fine. Can anyone suggest what's wrong with it?


Dissasemble and look for a welded joint between cells that has cracked
and making intermittent contact You may be able to repair with solder
but be careful not to apply too much heat to the cell. Conductive paint
and apatite have worked in some other applications.
--
John W
I you really want to mail me, replace the obvious with co.uk twice

John Weston wrote:
In article 3007ab9c-e345-4687-a7bf-392ce6fdceb0
@j9g2000vbp.googlegroups.com, "mike" wrote:
One of the battery packs on a cordless screwdriver has just started
playing up. Put it in the tool and nothing happens. Put a meter
across the terminals and the voltage fluctuates rapidly between zero
and just above the nominal value. (Other pack works fine and shows
steady, correct value on the meter.) I've taken it apart and all the
contacts look fine. Can anyone suggest what's wrong with it?


Dissasemble and look for a welded joint between cells that has cracked
and making intermittent contact You may be able to repair with solder
but be careful not to apply too much heat to the cell. Conductive paint
and apatite have worked in some other applications.

Conductive paint useless at such high currents.

On Aug 10, 10:27*am, The Natural Philosopher
wrote:
John Weston wrote:
In article 3007ab9c-e345-4687-a7bf-392ce6fdceb0
@j9g2000vbp.googlegroups.com, "mike" wrote:
One of the battery packs on a cordless screwdriver has just started
playing up. *Put it in the tool and nothing happens. *Put a meter
across the terminals and the voltage fluctuates rapidly between zero
and just above the nominal value. *(Other pack works fine and shows
steady, correct value on the meter.) *I've taken it apart and all the
contacts look fine. *Can anyone suggest what's wrong with it?

Dissasemble and look for a welded joint between cells that has cracked
and making intermittent contact *You may be able to repair with solder
but be careful not to apply too much heat to the cell. *Conductive paint
and apatite have worked in some other applications.

Conductive paint useless at such high currents.

yes, utterly. Solder, or tie together with wire if you dont have
soldering kit. If there isnt enough to do that either, wedge the cell
somehow for a forced contact.


NT

In article , "The Natural Philosopher"
wrote:
John Weston wrote:
In article 3007ab9c-e345-4687-a7bf-392ce6fdceb0
@j9g2000vbp.googlegroups.com, "mike" wrote:
One of the battery packs on a cordless screwdriver has just started
playing up. Put it in the tool and nothing happens. Put a meter
across the terminals and the voltage fluctuates rapidly between zero
and just above the nominal value. (Other pack works fine and shows
steady, correct value on the meter.) I've taken it apart and all the
contacts look fine. Can anyone suggest what's wrong with it?


Dissasemble and look for a welded joint between cells that has cracked
and making intermittent contact You may be able to repair with solder
but be careful not to apply too much heat to the cell. Conductive paint
and apatite have worked in some other applications.

Conductive paint useless at such high currents.

Agreed, but "in some other applications"...
--
John W
I you really want to mail me, replace the obvious with co.uk twice

John Weston wrote:
In article , "The Natural Philosopher"
wrote:
John Weston wrote:
In article 3007ab9c-e345-4687-a7bf-392ce6fdceb0
@j9g2000vbp.googlegroups.com, "mike" wrote:
One of the battery packs on a cordless screwdriver has just started
playing up. Put it in the tool and nothing happens. Put a meter
across the terminals and the voltage fluctuates rapidly between zero
and just above the nominal value. (Other pack works fine and shows
steady, correct value on the meter.) I've taken it apart and all the
contacts look fine. Can anyone suggest what's wrong with it?


Dissasemble and look for a welded joint between cells that has cracked
and making intermittent contact You may be able to repair with solder
but be careful not to apply too much heat to the cell. Conductive paint
and apatite have worked in some other applications.
Conductive paint useless at such high currents.

Agreed, but "in some other applications"...

agreed but those other applications are now what the poster was on about..