Searching \ for '[EE] Batteries that have memory' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/power/batterys.htm?key=batteries
Search entire site for: 'Batteries that have memory'.

Exact match. Not showing close matches.
PICList Thread
'[EE] Batteries that have memory'
2008\07\01@190624 by Jinx

face picon face
> Is it simple chemistry or something else?

Sometimes it's just sh%#^y manufacture and maintenance. I've just
had both battery packs apart on my B&D 18V cordless drill to give
the cells a zap ** because the packs as a whole refuse to charge to
any useful amount. I mentioned, in passing, this charge issue to the
power tools staff where I got the drill from and the response was
"oh, that's memory", because that's about all they know of battery
faults

** in each pack, about half the cells showed very close to 0V after
a charge. Others had very weak charge and you'd be lucky to drill
one hole. These are not old packs and haven't had a lot of cycling.
The "charger" is just an unregulated PSU that the cells simply take
energy from. With so many dead cells in series the living can't take
all that much

One trick to re-vitalise a cell is to charge a few 1000uF to 12-15V
and dump it across the cell. This is said to break down the dendrites
(which either short the electrodes or create high series resistance, I
forget which) and prevent proper charging. After 3-4 goes at this, the
cell voltage should rise to over a volt. When all the dead cells have
been zapped the pack can go back in the charger. It's the first time
I've needed to do this for these packs, and now they charge like new

A similar principle is to hold 12-15V on the cell and remove it as
soon as the cell voltage rises abrubtly. I've tried this on other packs
in the past and it seems to work alright. Have to be careful though

2008\07\01@192611 by Carl Denk

flavicon
face
Thanks for the tips :)

Just so I understand correctly for the 1000uf method. Could this be a
cap of larger values, say as much as 3000uf?
1: Take the cap to a 12-15 VDC supply
2: Connect the cap "-" to the ground PSU terminal, and the "+" to the
PSU 12-15 VDC terminal briefly, say 15 seconds.
3: Disconnect the cap from the PSU, and connect the cap to one cell of
the battery pack observing polarity again. Leave connected say 15 seconds.
4: Repeat for each cell in the pack, and repeat 3 or 4 times per cell.

We have used http://www.primecell.com several times with no complaints to
rebuild power tool batteries. They also rebuild batteries for a wide
variety of devices. On a Metabo drill pack, I couldn't even detect where
they cut the battery pack apart, made me wonder of they just zapped the
pack, but it performs better than the OEM packs.

Jinx wrote:
{Quote hidden}

2008\07\01@195746 by Jinx

face picon face
> Just so I understand correctly for the 1000uf method. Could this be
> a cap of larger values, say as much as 3000uf?

I zapped these cells using 9000uF (PSU reservoir). The point is you
need an inrush of current to break the dendrites. A few 1000uF isn't
even close to the J capacity of a cell so there's no danger of the cell
voltage rising too high

> 1: Take the cap to a 12-15 VDC supply
> 2: Connect the cap "-" to the ground PSU terminal, and the "+" to the
> PSU 12-15 VDC terminal briefly, say 15 seconds

It won't take that long, couple of seconds maybe

> 3: Disconnect the cap from the PSU, and connect the cap to one cell
> of the battery pack observing polarity again. Leave connected say 15
> seconds

Half-a-second. You'll probably see a spark and the cap will be discharged

> 4: Repeat for each cell in the pack, and repeat 3 or 4 times per cell

Correct. I clip the cap to the multimeter probes. Easy to handle and you
can see what's going on with the cell. When a pack has reached a certain
stage, you've got nothing to lose. Caught early enough, cells can return
to their former glory. Left to deteriorate I think the dendrites must build
up. You can blast one, creating a charge path, but the others left hold the
cell back from optimum performance

2008\07\01@212807 by Richard Prosser

picon face
Carl,

I've used higher voltage to achieve the same effect. I did have a
problem with a particularly troublesome cell however - 60V & 33000uF
blew an internal connection & permanently broke the cell. I don't
think the higher voltage does any harm as it initially discharges into
a short circuit. Any remaining energy just adds to the battery charge.
It's the energy level and temperatures reached that causes damage.

I've also fixed cells - at least temporarily - by _very, very briefly_
connecting them to a car battery.  But get them the wrong way around
and they're history.

Normally I find 20-30V on 1000uF or so seems to work OK but larger
cells seem to require more energy. I've also seen reports that
indicate that the higher energy the "blow" the longer time you get
before you have to do it again (within reason).

Richard P

2008/7/2 Jinx <spam_OUTjoecolquittTakeThisOuTspamclear.net.nz>:
{Quote hidden}

> -

2008\07\01@223759 by Jinx

face picon face
> I've also fixed cells - at least temporarily - by _very, very briefly_
> connecting them to a car battery.  But get them the wrong way
> around and they're history

;-) yes, they would be. That's the other technique. With a dead cell
and a current-limited PSU (at least current-limited compared with the
dump rate of a large cap) the voltage on the cell will sit at 0V for a
few seconds, maybe longer, and then the voltage suddenly rises as
the voltage forces a pathway and charge starts to be accepted. You
must must must whisk the voltage away as soon as you see that rise.
Or stand back

You could liken this rejuvenation to a hammer and nail. Applying
normal charge current/voltage into a very resistant cell is like trying to
get a nail in by pushing it with the hammer. What it really needs is a
good whack. Pulling the nail out (discharging the battery) leaves a
hole, meaning the nail *can* be pushed in the next time

2008\07\02@041103 by Alan B. Pearce

face picon face
>One trick to re-vitalise a cell is to charge a few 1000uF to 12-15V
>and dump it across the cell. This is said to break down the dendrites
...
>A similar principle is to hold 12-15V on the cell and remove it as
>soon as the cell voltage rises abrubtly. I've tried this on other packs
>in the past and it seems to work alright. Have to be careful though

I have done this with a 7.5V sealed pack that goes in my cordless drill. I
didn't do it as individual cells though, just momentarily touched the whole
pack across a car battery. Did the necessary to which cell(s) were faulty,
and it has operated fine ever since.

2008\07\02@082046 by Carl Denk

flavicon
face
Is the right way "+" to "+" and "-" to "-" ?

Jinx wrote:
>> I've also fixed cells - at least temporarily - by _very, very briefly_
>> connecting them to a car battery.  But get them the wrong way
>> around and they're history
>>    
>
> ;-) yes, they would be. That's the other technique. With a dead cell
> and a current-limited PSU (at least current-limited compared with the
> dump rate of a large cap) the voltage on the cell will sit at 0V for a
> few seconds, maybe longer, and then the voltage suddenly rises as
> the voltage forces a pathway and charge starts to be accepted. You
> must must must whisk the voltage away as soon as you see that rise.
> Or stand back
>
> You could liken this rejuvenation to a hammer and nail. Applying
> normal charge current/voltage into a very resistant cell is like trying to
> get a nail in by pushing it with the hammer. What it really needs is a
> good whack. Pulling the nail out (discharging the battery) leaves a
> hole, meaning the nail *can* be pushed in the next time
>
>  

2008\07\02@084853 by Jinx

face picon face
> Is the right way "+" to "+" and "-" to "-" ?

Yes. Make sure it's the bona fide +ve terminal and not just how
the battery reads. Sometimes cells will reverse polarity slightly,
ie you'll see a -ve voltage on the marked +ve terminal wrt to the
marked -ve terminal. Don't charge them in that polarity. Even if
the cells aren't marked + and -, you can tell by either the case
shape or trace back to the terminals for the whole pack


2008\07\02@111926 by Carl Denk

flavicon
face
Thanks for the warning, :) Probably should check polarity of the charger
to verify. :)

Jinx wrote:
{Quote hidden}

2008\07\03@010509 by Jinx

face picon face
Here's a coincidence. I got handed for repair today an Ikelight
12V NiCd pack (10 x D) that's used for underwater photography
lighting. It has a smart charger, which was indicating "no battery".
So, took it all apart. Usual story, some partially-charged, some 0V
cells. Gave it the zap and put it back on charge. This time the indicator
said "Pending Mode". What I had to do was put 1.4V on each cell
individually for a few minutes to get a little charge into them, then
put the whole pack back on the proper charger. This time it went into
Fast Charge Mode, and is looking pretty good now, probably better
than has for some time. The pack would be very expensive to replace
and well worth the 1/2 hour spent on it

2008\07\03@033052 by SM Ling

picon face
>From what I have tested, zapping recovered battery shall get shorted again
quite fast.  Maybe those I had were with older and bigger dentrides.  You
may want to also do a few cycle of conditioning with pulse charging.  Some
packs if left on shelf cannot remain un-shorted for a few days, most for a
few weeks, and none for a few months.  Frankly if it is not for hacking
pleasure, I would always rebuild with flash new cells.

Jinx, you want to try to do a quick and easy portable zapper with the
disposable camera flash unit?  I got hold of only 1 disposable camera, but
my experiment was not 100% good.  I think I managed to burn through some
short, but the flash unit failed after a few tries.

Cheers, Ling SM


On Thu, Jul 3, 2008 at 1:01 PM, Jinx <.....joecolquittKILLspamspam@spam@clear.net.nz> wrote:

{Quote hidden}

> -

2008\07\03@044706 by Jinx

face picon face
> Jinx, you want to try to do a quick and easy portable zapper
> with the disposable camera flash unit ?

I've got the schematic for a zapper like that. The storage cap is
470uF 200V. Energy content is about the same as the low voltage
method. Simpler with a cap and a PSU I reckon


2008\07\03@074508 by Michael Rigby-Jones

picon face


> -----Original Message-----
> From: piclist-bouncesspamKILLspammit.edu [.....piclist-bouncesKILLspamspam.....mit.edu] On
Behalf
> Of Jinx
> Sent: 03 July 2008 06:02
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE] Batteries that have memory
>
> Here's a coincidence. I got handed for repair today an Ikelight
> 12V NiCd pack (10 x D) that's used for underwater photography
> lighting. It has a smart charger, which was indicating "no battery".
> So, took it all apart. Usual story, some partially-charged, some 0V
> cells. Gave it the zap and put it back on charge. This time the
indicator
> said "Pending Mode". What I had to do was put 1.4V on each cell
> individually for a few minutes to get a little charge into them, then
> put the whole pack back on the proper charger. This time it went into
> Fast Charge Mode, and is looking pretty good now, probably better
> than has for some time. The pack would be very expensive to replace
> and well worth the 1/2 hour spent on it

Glad I'm not the only one that has good results from abusing NiCads in
this way.  Memory effect?  Teach them a lesson they'll never forget with
a car battery or large cap I say ;)

Mike

=======================================================================
This e-mail is intended for the person it is addressed to only. The
information contained in it may be confidential and/or protected by
law. If you are not the intended recipient of this message, you must
not make any use of this information, or copy or show it to any
person. Please contact us immediately to tell us that you have
received this e-mail, and return the original to us. Any use,
forwarding, printing or copying of this message is strictly prohibited.
No part of this message can be considered a request for goods or
services.
=======================================================================

2008\07\03@082533 by Jinx

face picon face
> Glad I'm not the only one that has good results from abusing
> NiCads in this way.  Memory effect?  Teach them a lesson
> they'll never forget with a car battery or large cap I say ;)

Aye, see you Jimmy !!!

At least this pack is charging now, something the owner just
couldn't get it to do. Apparently it's off to Wellington for a TV3
reporter to go diving in the harbour with. One of those over-paid
news presenters probably dropped their DB9 keys off the ferry .....

2008\07\03@084657 by Carl Denk

flavicon
face
Sounds like the capacitor method, is to ensure that the jolt isn't too
long a duration, as opposed to connecting to a beefy lead acid. Maybe
for the lead acid method, a smaller gauge wire might be appropriate,
like a 18 or 22 gauge, and be sure to wear eye protection and protect
hands from the heat or disintegration of the conductor. :)

Jinx wrote:
{Quote hidden}

2008\07\03@090114 by Jinx

face picon face
> Maybe for the lead acid method, a smaller gauge wire might be
> appropriate, like a 18 or 22 gauge, and be sure to wear eye
> protection and protect hands from the heat or disintegration of
> the conductor. :)

The battery method is safe (-ish) if you keep a close eye on the
voltmeter. No voltmeter ? No recommend battery method

2008\07\03@092210 by Carl Denk

flavicon
face
And, I'm only educated guessing here. ~)

If the beefy lead acid should be able to produce 50 or more amps short
term, and the wire size is large, say 12 ga. one of 2 thinks might happen:
1: The battery pack is shorted (or at least low resistance) initially:
   a: The battery pack short last briefly after connecting and the volt
meter across the battery pack is low voltage briefly reading the
resistance volt drop of the wire and internal battery, and then the
voltage comes up to near the battery open circuit voltage. This is what
I'm looking for below?
2: The battery pack is relatively high resistance with some relatively
high voltage cells, the voltmeter across the battery pack is some lower
value (nearer the sum of the partially charged + shorted cells), and I'm
looking for a jump in voltage as the shorted cells condition improves.

Either way, it looks like that lead acid is going to put out lots of
amps briefly, and the possibility of an exploding cells is there, and
appropriate safety precautions are in order!

And this method is OK to try whether the pack is 1.5 or 18 volts, or
should voltage be adjusted for number of cells?

Thanks again for the info. :)

Jinx wrote:
>> Maybe for the lead acid method, a smaller gauge wire might be
>> appropriate, like a 18 or 22 gauge, and be sure to wear eye
>> protection and protect hands from the heat or disintegration of
>> the conductor. :)
>>    
>
> The battery method is safe (-ish) if you keep a close eye on the
> voltmeter. No voltmeter ? No recommend battery method
>
>  

2008\07\03@094316 by Rolf

face picon face
Hi, I believe the initial statement was that the pack had to be broken
down to individual cells. You can't 'zap' the pack, just each cell
individually.

Rolf

Carl Denk wrote:
{Quote hidden}

2008\07\03@101341 by Ariel Rocholl

flavicon
face
Just for reference, most R/C "high end" NiCd/NiMh chargers will do
short burst of up to 10C to remove this effect automatically when
charging.

TTYL

--
Ariel Rocholl
Madrid, Spain

2008\07\03@111131 by Carl Denk

flavicon
face
And then bring each cell up to full charge individually, before placing
back in service, and then recharge the pack as a whole. :)

Rolf wrote:
{Quote hidden}

2008\07\03@213405 by Jinx

face picon face
> And then bring each cell up to full charge individually, before
> placing  back in service, and then recharge the pack as a whole. :)

Sometimes you need to "encourage" a cell to accept charge by
giving it special attention over others in the pack, and part-charging
it on its own might be necessary

To break it down, yo yo yo break it down -

Say you've got a drill and a six-pack. The missus says, "I'm sick of
seeing you flash your abs, pull that shirt down, take your drill and go
fix my shelf". But you find the drill won't charge. Uh-oh, spaghetti-o

That generally means one or more cells in the pack has become
resistive/resistant. It's probably also 0V. The normal charger
hasn't got enough current behind it to force-charge the pack with
that cell in it. So you have to identify any cells stopping the charge
going in. Once you find them, you give them a zap with a cap

If you can't get to both +ve and -ve terminals, the outer case of
one is often the other electrode of the one next to it. eg the case
of cell1 is its -ve, the case of cell2 is cell1's +ve, if cell1 is at the
-ve end of the pack for example

After zapping the cell(s), put the pack back on the charger. If it
still won't accept a charge, put some charge individually in each
cell in the pack. Somehow apply about 1.4V to it. That's usually
enough to get the pack conditioned for a full charge

2008\07\04@233512 by Peter Todd

flavicon
face
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On Fri, Jul 04, 2008 at 01:31:49PM +1200, Jinx wrote:
> To break it down, yo yo yo break it down -
>
> Say you've got a drill and a six-pack. The missus says, "I'm sick of
> seeing you flash your abs, pull that shirt down, take your drill and go
> fix my shelf". But you find the drill won't charge. Uh-oh, spaghetti-o

That paragraph was brilliant; I just put it in my quotes file.

- --
http://petertodd.org 'peter'[:-1]@petertodd.org
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.6 (GNU/Linux)

iD8DBQFIbuNX3bMhDbI9xWQRAverAJsFqX5oIjMRwfqTXG5ZUcy83T1MwgCfXFeQ
V4ZffeN6dawxKG+vUDBo4Fc=
=KDMw
-----END PGP SIGNATURE-----

2008\07\05@002926 by Jinx

face picon face
> That paragraph was brilliant;

hehe, cheers

I've just used my newly-rejuvenated cordless drill to replace the
toilet-roll holder. It's a nice one too. Kinda makes the rest of the
place look squalid actually, which is a bit of an aesthetic nuisance,
but we'll dirty it up in no time ;-)

More... (looser matching)
- Last day of these posts
- In 2008 , 2009 only
- Today
- New search...