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Batteries: autopsy and restoration

Subject: Batteries: autopsy and restoration
From: Vicki Powys <>
Date: Thu, 13 Jun 2002 17:37:51 +1000
Hi Walt and All,

Well I got busy with my (very fine) hacksaw and sliced open the plastic
casing of my defunct Sony  D10 DAT battery (NP-22H 6 volt 1800 mAh
rechargeable ni-cad).  There were three cells inside, two long and one
short, linked by 2 short wires to a mysterious silvery connector 2cm long
(which is marked IP305AF  80C  ISUZU  0A3.)

The two long cells look for all the world like "tuppeny bungers"
(firecrackers), but are yellow instead of red. The batteries are about 2.25
cm diameter, is that about the thickness of C cells?

I now have to decide what I would use for the replacement cells, assuming
that I go with NIMH rechargables.  Should I use 4 or 5 AA cells, or should =
I
go for C cells?  What are the dimensions of C cells?

Rechargeable cells often run at a lower voltage than disposable long-life
cells, would this make a difference in the number of cells I used?

What is the voltage of a freshly charged rechargeable C cell?

The original Sony battery pack, when new and freshly charged, put out up to
7 volts I think (the battery pack is marked 6 volt), and the tape stops
turning at 5.9 volts (5.5v under load).

All ideas welcome!

Vicki Powys
Australia













on 9/6/02 3:10 PM, Walter Knapp at  wrote:

> Vicki Powys wrote:
>
>> You are full of good ideas!  Actually I DO still have two dead battery p=
acs
>> but I may have to use a hacksaw to open the plastic casing, looks like i=
t's
>> glued together.  Size-wise, each pac could hold up to six AA batteries.
>>
>> So the thought occurred to me, could I just open up the case, trash the
>> ni-cad contents, and re-mount five AA batteries of the NIMH sort? (What =
does
>> NIMH stand for?)  Of course I would need a NIMH AA battery charger, but =
if I
>> had the case sorted out so I could easily mount or retrieve the AAs, I c=
ould
>> even use non-rechargeables in an emergency.
>>
>> What do you think of that idea?
>
> I almost never toss a battery pac without dissecting it. Some can be
> fixed up with new cells so easily it's child's play. My portable drill,
> for instance. It comes apart with screws, and inside are a bunch of C
> cell size nicads with solder terminals and one thermister. And then
> there are others that will drive you nuts even getting apart...
>
> NIMH stands for Nickel Metal Hydride, a battery type. It has the
> advantage over nicads that it's almost immune to memory effects. And the
> amount of energy it will store, either on a weight or volume basis beats
> nicads by at least 40%.
>
> You were probably going to throw away those pacs, so might as well learn
> something. Note that cutting open with a hacksaw is kind of crude, the
> wide slot can be a problem putting it back together. If I get to sawing,
> which is rare, I normally will use a coping saw or jeweler's saw, which
> have much finer blades. In most cases, I'm more likely to just crack the
> case by prying with things like screwdrivers. The crack will go back
> together essentially with the same dimensions.
>
> It all depends on what you find inside, explore carefully.
>
> Depending on your resources, It may also be possible to design a
> improved pac that will fit in something. I've been eyeing the
> Portadisc's AA cell holder for just such a replacement job. One of mine
> already has a crack in it near the vulnerable center rivets. So, I've
> been thinking about a tubular design.
>
>> By the way, the Sony recharging unit (both mains and car) automatically
>> switches itself off when the battery is charged, so there's no risk ther=
e of
>> overcharging.
>
> Most modern chargers do this. But with some there is still a way to
> overcharge. If the charger uses a timer that resets if it loses power
> (like in a momentary power outage) and it then does another fast charge
> by timer... Or if it resets if the battery loses contact...
>
> Walt
> 
>



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