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Discharging NiCad Cordless Battery Pack

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Discharging NiCad Cordless Battery Pack newsomer 06-02-2008
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Posted by newsomer on June 2, 2008, 10:52 am
Hello, first post here.

I know NiCad recharging has been discussed extensively here. I know this
because I tried to research my answer by searching previous discussions
and didn't find anything that would answer my question completely.

I have a three year old set of Craftsman 18 volt NiCad cordless drill and
flashlight. What I would like to know is that if I use the battery in the
drill until it is to weak to perform satisfactorily then swap it into the
flash light and leave it burning until the light goes out will there be
enough resistance in the light bulb to prevent the battery from
discharging completely and ruining the battery pack?

To infinity and beyond!
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Posted by ransley on June 2, 2008, 11:04 am
On Jun 2, 9:52=A0am, robert.newsome_at_us_dot_army_dot_...@foo.com
(newsomer) wrote:
> Hello, first post here.
>
> I know NiCad recharging has been discussed extensively here. I know this
> because I tried to research my answer by searching previous discussions
> and didn't find anything that would answer my question completely.
>
> I have a three year old set of Craftsman 18 volt NiCad cordless drill and
> flashlight. What I would like to know is that if I use the battery in the
> drill until it is to weak to perform satisfactorily then swap it into the
> flash light and leave it burning until the light goes out will there be
> enough resistance in the light bulb to prevent the battery from
> discharging completely and ruining the battery pack?
>
> To infinity and beyond!
> -------------------------------------
>
> ##-----------------------------------------------##
> Delivered via =A0http://www.thestuccocompany.com/
> Building Construction and Maintenance Forum
> Web and RSS access to your favorite newsgroup -
> alt.home.repair - 293294 messages and counting!
> ##-----------------------------------------------##

By the time the drill is slowed nicads are discharged, any further
running or draining them risks reversing cells polarity. A nicad is
fully charged at about 1.35v a cell and discharged at 1.2. What you
propose will ruin your pack

Posted by AZ Nomad on June 2, 2008, 5:41 pm
>On Jun 2, 9:52 am, robert.newsome_at_us_dot_army_dot_...@foo.com
>(newsomer) wrote:
...
>> drill until it is to weak to perform satisfactorily then swap it into the
>> flash light and leave it burning until the light goes out will there be
>> enough resistance in the light bulb to prevent the battery from
>> discharging completely and ruining the battery pack?

>By the time the drill is slowed nicads are discharged, any further
>running or draining them risks reversing cells polarity. A nicad is
>fully charged at about 1.35v a cell and discharged at 1.2. What you
>propose will ruin your pack

There is always a "weakest cell". It isn't that he's running it past 1.2V. What
he is doing is forcing current through a 0V cell, charging it in reverse.


Posted by AZ Nomad on June 2, 2008, 12:26 pm
On 02 Jun 2008 14:52:21 GMT, newsomer
>Hello, first post here.

>I know NiCad recharging has been discussed extensively here. I know this
>because I tried to research my answer by searching previous discussions
>and didn't find anything that would answer my question completely.

>I have a three year old set of Craftsman 18 volt NiCad cordless drill and
>flashlight. What I would like to know is that if I use the battery in the
>drill until it is to weak to perform satisfactorily then swap it into the
>flash light and leave it burning until the light goes out will there be
>enough resistance in the light bulb to prevent the battery from
>discharging completely and ruining the battery pack?

1) nobody uses nicads any more. It is probably NIMH which work similarly but
give longer life and require more carefull charging. Lithium Ion is now
replacing NIMH.

2) When the the drill starts to run slower, discontinue use of the battery
IMMEDIATELY! What kills rechargeable batteries is when the weakest cell is
discharged and the rest of the battery is forcing current through it, in effect
charging the weakest cell in reverse which will short it out.

Then charge it! Don't fuck around by swapping it around. The only place to put
the battery is back in the charger. If you put it in the flashlight and keep
running it, you'll quickly ruin it.

I've also found that batteries left discharged will get ruined. I've used
rechargeables for decades and the only time they've ever failed me is when I've
stopped using a set for a long time. Recharge them periodically to prevent
discharging.


Posted by ransley on June 2, 2008, 12:56 pm
> On 02 Jun 2008 14:52:21 GMT, newsomer <robert.newsome_at_us_dot_army_dot_.=
..@foo.com> wrote:
>
> >Hello, first post here.
> >I know NiCad recharging has been discussed extensively here. I know this
> >because I tried to research my answer by searching previous discussions
> >and didn't find anything that would answer my question completely.
> >I have a three year old set of Craftsman 18 volt NiCad cordless drill and=

> >flashlight. What I would like to know is that if I use the battery in the=

> >drill until it is to weak to perform satisfactorily then swap it into the=

> >flash light and leave it burning until the light goes out will there be
> >enough resistance in the light bulb to prevent the battery from
> >discharging completely and ruining the battery pack?
>
> 1) nobody uses nicads any more. =A0It is probably NIMH which work similarl=
y but
> give longer life and require more carefull charging. =A0Lithium Ion is now=

> replacing NIMH.
>
> 2) When the the drill starts to run slower, discontinue use of the battery=

> IMMEDIATELY! =A0What kills rechargeable batteries is when the weakest cell=
is
> discharged and the rest of the battery is forcing current through it, in e=
ffect
> charging the weakest cell in reverse which will short it out.
>
> Then charge it! =A0Don't fuck around by swapping it around. =A0The only pl=
ace to put
> the battery is back in the charger. =A0If you put it in the flashlight and=
keep
> running it, you'll quickly ruin it.
>
> I've also found that batteries left discharged will get ruined. =A0I've us=
ed
> rechargeables for decades and the only time they've ever failed me is when=
I've
> stopped using a set for a long time. =A0Recharge them periodically to prev=
ent
> discharging.

I just bought Nicads yesterday, I didnt feel 3.5x the price for LiIon
was worth it for occasional use. Also let the pack rest a day to cool
before recharging, cells work by a chemical reaction , letting packs
rest has gotten me 20 years on packs. Heat also kills cells, as in
overcharging and rapid discharge,

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