opnions wanted on battery reviving of NiCads

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dacflyer
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opnions wanted on battery reviving of NiCads

Post by dacflyer » Thu Apr 16, 2009 9:15 am

i was searching to look for a replacement battery for a old B&D drill i have..can't find one yet, but i stumbled across this ad in ebay.. is this BS or does it work ?
the batterys i have now actually will either not take a charge or hold one..

http://cgi.ebay.com/Fix-For-Black-Decke ... 7C294%3A50

currious if i should try this or not..

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Externet
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Re: opnions wanted on battery reviving of NiCads

Post by Externet » Thu Apr 16, 2009 10:05 am

Ni-Cd's were born bad, since they were designed :sad: . Discard them and replace with Ni-mH ; make your own pack.

Let us know if you try the link.
Miguel
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Re: opnions wanted on battery reviving of NiCads

Post by Rodney » Thu Apr 16, 2009 11:11 am

I would not recommend that device. What most often happens to a NiCad is that the seperator has been peirced by the internal growth of large crystals. What this device most probably does it put in a very high pulse of current that literally vaporizes that crystal which removes the short and lets the battery now take a charge. However, the hole in the separator is still there and soon a new crystal growth (as happens under the charge cycle) will soon reappear and cause an internal short again. In general, a NiCad is a better choice than NiMh as they will take twice as many charge/discharge cycles than a NiMh will, have less internal impedance than a NiMh and is more immune to minor abuse than a NiMh is. Here is some good info on batteries:
http://www.srbatteries.com/nimh.htm
http://dansdata.com/gz011.htm
http://users.frii.com/dlc/battery.htm

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Re: opnions wanted on battery reviving of NiCads

Post by ringo47stars » Thu Apr 16, 2009 12:38 pm

For that price and list of equipment needed you would probably need that like a hole in the head (gloves, safety goggles). But if it works I would recommend repairing ni-cads or ni-mh batteries every 3 months or so also. So I think nickel-metal-hydride ones last longer than ni-cads my-self but some people don't agree. If you factor in the responses with the available methods of repairing batteries it would take more information on the abuse the battery is put through to determine that.

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Re: opnions wanted on battery reviving of NiCads

Post by dtief » Thu Apr 16, 2009 5:41 pm

BTDT
Zapping the shorts out of dead NiCads works as a science experiment. For a short time. They will not be restored to new capacity. They will go bad again pretty quickly.

I've rebuilt a few drill batteries over the years. Very short procedure:

Open the case. Measure the cells. Look up the cells on DigiKey or similar. You want high rate cells most likely for a drill. Re use the high temperature paper insulators from the original pack. The shrink plastic ones can melt & cause a short.

Do not allow any 1 cell in the pack to be discharged below 1V. This means as soon as the drill power has the typical noticable drop, STOP using it & recharge. When that cell starts to get reverse charged, it develops the crystals that cause the shorts...

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Re: opnions wanted on battery reviving of NiCads

Post by dacflyer » Fri Apr 17, 2009 4:50 pm

dtief said... > Do not allow any 1 cell in the pack to be discharged below 1V. This means as soon as the drill power has the typical noticable drop, STOP using it & recharge. When that cell starts to get reverse charged, it develops the crystals that cause the shorts...


Ahhhh. maybe that was my problem, i thought it was good to almost totally kill a nicad, so it wouldn't have the memory effect. Hmmmm

and so if i understand right, nickle hydride batterys are better ? will my current charger still be ok to use ? the packs are made up of sub-c cells. they typical 7.2 volt pack.
i like my drills, they are still relatively light, i am not fond of the big bulky ones nowdays..

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Re: opnions wanted on battery reviving of NiCads

Post by dtief » Fri Apr 17, 2009 7:56 pm

I wouldn't change the battery type. The NiMH will cost a lot more. They have more capacity for the same case size. Higher self discharge rate. Lower cycle life. Deep cycles & high current aggravate this.

What many times looks like memory effect is in fact the weakest cell dropping below 1V, and even reverse charging. Each time this happens, that cell gets further behind the better ones, and in the event of over discharge, it gets further damaged by the reverse charging. The run time gets shorter & shorter. This also is effected by the charger - how well it is designed. There is a certain amount of overcharge that is supposed to equalize the cells - bring that weakest one up to the level of the better ones. Too much overcharge is of course, bad. Deep cycles are harder on batteries than shallow ones. But if the charger isn't built to adjust to the state of charge, it can look like the opposite.

The best way to rebuild a pack is to get a few extra cells and match them for capacity. A lot of work though.

I have an older Milwaukee drill 9.6V that I bought when it was current technology. Something like 20+ years ago. It is still my favorite, even though I've tried newer more powerfull models. The instant it drops speed, I throw the battery on the charger. Remove the battery from the charger soon as possible after charging. I have always had long battery life. It would be better to recharge before it drops, but it is hard to know that....

Meanwhile, at work, they had the same drills. But I would always catch the production workers trying to run them well past that point. Leaving the batteries on the chargers over night, or for days even. They always had short battery life.

A couple of years ago, I came across 2 of the identical drills on ebay, and another auction for a bunch of batteries & chargers. (that one the guy even found the (dead) drill & included it in the shipment!) I got them all for maybe $75.00. Then they bought newer drills at work, and I saved the old ones from the dumpster. So now I have 5 working & one parts drill! So nice not having to change bits all the time.

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Re: opinions wanted on battery reviving of NiCads

Post by Janitor Tzap » Fri Apr 17, 2009 8:35 pm

Hey dacflyer,

NiCad's are funny in that they can short, or they vent all they're electrolytes.
From over charging the cells.

I've got a "NiCad Zapper".
I built it sometime ago for a large batch of AA's,
that I wanted to see if I could remove the shorts from.

Well, it only sort of worked on a few cells.
But like dtief said...
Zapping the shorts out of dead NiCads works as a science experiment. For a short time. They will not be restored to new capacity. They will go bad again pretty quickly.
Also, when you rebuild the Battery Pack, or Packs.
Replace all the cells at the same time.
Replacing only the bad cells in the pack, will bite you back later.

One thing that some battery re-builders do, is matching of the cells first.
Before they are put them into a pack.
This is so each cell charges and discharges basically at the same rate.
Basically this involves checking the resistance of the cells in they're discharged & charged states.
And closely matching the voltages of the cells together.
Then the pack is cycled through a charge & discharge cycle a few times.

1.2Vdc cells when fully charged will read about 1.34Vdc.
The discharged point is about 1.08Vdc.
Discharge the cell more than that, and you risk reverse charging it.

Thus, a 12Vdc pack fully charged is about 13.4Vdc.
It's discharged point would be around 10.8Vdc.

As for switching to a nickel-metal-hydride battery packs.
They require a different charging scheme, and are less forgiving then the NiCad Packs.

Lithium ion batteries also need a very different charging scheme.
But even though they provide higher current for more power.
They need to be recharged more often then Nicad, or the Nimh battery packs.
Some contractors I talked too have these new Ion Power Tools.
They normally have three batteries per-tool.
One on the tool, One extra charged battery on the tool belt.
And one sitting in the charger.
:lol:


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Re: opnions wanted on battery reviving of NiCads

Post by MrAl » Sat Apr 18, 2009 4:21 am

Hello dac,


I have had problems with NiCd's in the past too, and a few had shorted out and i zapped
them with a wall wart that had an internal capacitor and a voltage that was well
above the NiCd cell voltage (like 9v).
After the zapping the cells began to take a charge again, but i found that it wasnt
long before they needed it again, and also that the capacity seemed to reduce
quite a bit. This might be because they were old anyway.

I found that the best thing to do was to bite the bullet and buy some decent brand
new NiCd's and replace the cells. This can be a bit expensive, but you end up with
something that works very well versus something that you never know when it will
work and when it wont.
I had bought some cells at (of all places) Radio Shack, and was quite happy with
them as they all tested at a higher capacity than advertised. These were the new
type they sell now not the old type which were not as good.

As far as replacing them with NiMH, that's almost not possible, or at least this
should not be done at all. The reason being that NiMH's require a different
charging strategy and trying to charge them with a charger that was made for NiCd
will beat them up too fast to be worthwhile. NiCd chargers for tools (and even
other devices) are often made as simple as possible, and they abuse the NiCd's quite
a bit...but the NiCd's can take this abuse to a point, while the NiMH's can not take
this kind of charging and will die too fast to be practical.
Really the only way to charge the NiMH is with a special charge algorithm, which
no charger made for NiCd's will ever have unless it was built for BOTH chemistries.
The other thing is that NiCd's can deliver a higher current than NiMH and this is
what makes them work so well with cordless power tools.
Another problem comes up however when trying to use NiMH in a battery pack.
This is the problem where it is very hard if not impossible to monitor the votlage
of each and every cell individually, and therefore it is not possible to charge
the pack correctly every time. NiMH cells require that their voltage be monitored
during the charge process so that the charge can be terminated at the right time.
By connecting a large number of them in series (as for a battery pack) it is hard
to monitor each and every individual cell without running lots of wires to some
kind of monitor/charger. This means that packs will usually be found being
charged in series also, which is NOT the way NiMH cells were meant to be charged.
Some of the cells may become charged sooner than others, which could mean that
those cells overcharge for a long time while waiting for the other cells come up to
speed. This would cause some cells to die much faster than others. This is yet
another reason why i never recommend building a pack out of NiMH's, unless the
voltage of each cell is monitored.
There are other problems that can come up too with NiMH packs. When the cell
reaches its full charge state the voltage begins to decline, while before this time
the cell voltage is rising. This means one cell might be rising while the other cell
is decreasing (a decrease normally tells the charger it's time to stop charging) and
the two cancel each other out, meaning the charger may never ever detect end
of charge which means the cells charge forever unless there is a back up charge
termination method (always recommended anyway) which only allows a certain time
for the charge to take place and then ends it regardless of the state of any of
the cells.

A recent trend is to use Li-ion cells in power tools. This kind of chemistry is
VERY sensitive to the charge algorithm...even more so than NiMH. This means that
you need a very specialized charger to charge these kinds of cells or they will
very, very quickly burn up, and that doesnt just mean that they will burn out
and not work anymore, but will literally blow up and start flaming. This is no
joke either. There are reports all over the web that attest to this kind of
possible problem, and almost every time it is associated with the cell being
charged at the time of the incident. In other words, charging has to be done
very, very carefully following a very strict charge regime or else there is a
big risk of a fire starting.

Interestingly, a charger for Li-ion is very much like a charger for Lead Acid,
so there are cheap ways to build very reliable chargers, while NiMH require
a special chip or a microcontroller, and NiCd only requires a wall wart with
some limit on the time of charge.

To recap some important facts:

Replace NiCd with NiMH? Not unless the charger is also changed to handle NiMH.
Replace NiCd with Li-ion? Definitely not, unless the charger is also changed.
Do either of the above for a short time period? NiMH will last a little while,
while Li-ion will smoke and flame and cause a fire.
Last edited by MrAl on Sat Apr 18, 2009 6:22 am, edited 2 times in total.
Reason: Spelling, clarity, added content.
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Re: opnions wanted on battery reviving of NiCads

Post by Lenp » Sun Apr 19, 2009 4:46 am

Dacflyer,

Before you get too into this project check out http://www.primecell.com.(No interest, they are a N&V advertiser)
They can rebuild most tool battery packs for about YOUR cost for the cells. and, without welded links it may be a tight squeeze. We are using several rebuilt B&D/Dewald packs that are running strong after about 3 years.
We usually option for the upgrade to higher capacity cells, and it seems to be worth it. Turnaround time is usually about a week plus shipping time for PA.

Zapping a cell is an exercise in futility!

Len
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Re: opnions wanted on battery reviving of NiCads

Post by MrAl » Sun Apr 19, 2009 7:49 am

Lenp wrote:Dacflyer,

Before you get too into this project check out http://www.primecell.com.(No interest, they are a N&V advertiser)
They can rebuild most tool battery packs for about YOUR cost for the cells. and, without welded links it may be a tight squeeze. We are using several rebuilt B&D/Dewald packs that are running strong after about 3 years.
We usually option for the upgrade to higher capacity cells, and it seems to be worth it. Turnaround time is usually about a week plus shipping time for PA.

Zapping a cell is an exercise in futility!

Len

Hi Len,

Their prices look pretty good, i noticed only 25 dollars US for an 8 cell portable device, but then
i also noticed that the UPS shipping would cost 22 dollars US, wow. That's almost 50 bucks.
Too bad the shipping is so much. On the other hand when i rebuilt it myself it cost me 40 bucks
plus tax, and i had to rebuild it myself.
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Re: opnions wanted on battery reviving of NiCads

Post by sofaspud » Sun Apr 19, 2009 10:53 am

Seems to me that battery charging/memory followed not far behind religion & politics
as internet controversies. Here's a couple of the better info sources that I've run across:
nicad FAQ - a no-brainer, several host sites
Batteries In A Portable World - a free online book which is quite comprehensive. Find it
here -> http://www.cadex.com/battery_info/
Check out the Panasonic website too. They have some decent pdf handbooks for NiCd
and NiMH users.
I tend to conclude that with rechargeables, it's most important to not treat them badly.
They'll survive a bit of "not treating them rightly." Applicable to all, but truest for NiCd
and lead acid types.

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Re: opnions wanted on battery reviving of NiCads

Post by Bob Scott » Sun Apr 19, 2009 12:40 pm

I have had custom battery packs rebuilt at a local builder.
http://www.excellbattery.com/
I've had them custom make packs for my kids' toy RC cars and also make replacement packs for Anton Bauer broadcast ENG equipment at work, at inexpensive prices. They are way cheaper than OEM. Don't all medium sized cities have a local battery rebuilder? They are like CRT rebuilding places, every city used to have one. You have the freedom to choose from many cell brands with various specifications. They spot weld them together and bind with thin plastic shrink wrap.
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Re: opnions wanted on battery reviving of NiCads

Post by dacflyer » Sun Apr 19, 2009 5:56 pm

batteries + does that here, but they want more to rebuild a pack than what a new one cost..
they are out of their mind.. they wanted 75.00 for my drill pack 7.2 volt

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Re: opnions wanted on battery reviving of NiCads

Post by Janitor Tzap » Mon Apr 20, 2009 2:46 pm

dacflyer,

Have you checked the prices from Digikey?

They have the cells with or without solder tabs.
They can also make up packs for you. :)
(Catalog Page# 2210 - 2211)

Your drill's Battery Pack is most likely made up of C or Sub-C cells.
Here's the cheapest in Ni-Cd SANYO Batteries they carry.
SY120T-ND SC - 1.2V 1300ma with tabs: $4.13 x 6 = $24.78
SY123T-ND C - 1.2V 3000ma with tabs: $8.98 x 6 = $53.88

I would also check places like.....
Electronic Goldmine. http://www.goldmine-elec.com/
American Science & Surplus. http://www.sciplus.com/
Surplus Gizmos. http://www.surplusgizmos.com/

I've bought old, but never used battery packs from Electronic Goldmine.
To rebuild dead Ni-Cd Laptop Batteries.
It worked out pretty good.
I rebuilt the packs for at least half of what a new one's were costing. :)

Or look here.
http://www.harborfreight.com/cpi/ctaf/d ... mber=93655
At that price, I'd buy the battery, and take it apart for just the cells. :lol:


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