Slimy38
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| posted on 27/12/13 at 01:44 PM |
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recovering nicd batteries?
I'm considering buying another drill as my current one has no working batteries. However, I've just seen a method online to
'recover' a nicd battery by zapping it with a higher voltage. Apparently it destroys the crystal formation that prevents the cells from
working, the so-called memory effect.
Has anyone ever done this to recover a nicd battery? If it does work, anyone got any ideas how I could find/create a 36 volt power source (given that
the batteries are 18v).
I'm not overly worried if it doesn't work, they were destined for the bin but if they can be recovered then it's a good thing.
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John P
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| posted on 27/12/13 at 02:02 PM |
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I looked into this but eventually bought a new drill so I can't say if it works.
The article I read suggested using two 12 volt batteries in series so they were presumably using 24 volts to recover an 18 volt NICD battery.
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CNHSS1
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| posted on 27/12/13 at 02:04 PM |
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I used to work in the model industry, was pretty common place.
best way (by far!) is to open the pack up and look at each cell in isolation. if its 18v pack there will be 15 cells (1.2v nominal per cell).
put a small load across the pack terminals, such as a 5w bulb (two in series if theres still some charge in the pack).
then check each cells voltage with a multimeter. In all likelihood you will find most of the cells are OK, with one or a couple either dead or
reversed polarity. If this is the case, only 'flash' the dead/reversed cells. I used a 12v battery or battery charger, so a couple of
seconds. Then re-check the duff cells to see if they are alive/positive voltage. If they are, recharge the whole pack using the proper charger, but
don't reassemble the case.
once recharged, stick a decent load across the pack terminals (id suggest a couple of headlamp bulbs in series (18v pack needs a 24v load, one bulb
will blow). with that load (approx. 42watts) check each cells voltage individually. so long as the duff cells aren't weak, then you may have got
away with it. if they immediately show a poor voltage or reverse polarity, then they need to be pulled out and replaced with new (couple of quid
each).
if you do replace a cell(s) with new, try to charge them individually before assembling into a part charged pack, or you will create a charge
imbalance across the cells again.
NiCd are as tough as old boots, and generally recover, but if not replacing the offending cells is cheap and easy.
one last thing, try not to run the drill dead flat in future, certainly for the first few use cycles after the repair/replacement, just to give them a
chance to all get along again.
above doesn't apply to NiMh ( nickel metal hydride) or LiPo or LiOn cells (lithium polymer or lithium ion), double check they are old skool
nicads first!
any queries, just holla
CNH
"Racing is life, everything else, before or after, is just waiting"---Steve McQueen
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CNHSS1
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| posted on 27/12/13 at 02:05 PM |
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doing the 'flash' across the pack doesn't single out the poorly cells and can bugger the good cells, must be done at cell level and
not pack level imho
"Racing is life, everything else, before or after, is just waiting"---Steve McQueen
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Slimy38
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| posted on 27/12/13 at 05:44 PM |
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Thanks for the pointers. Cell by cell makes sense, I've already opened the pack and can see the individual cells. They're a bit of an odd
physical size though so I'll have to look into where to get replacements from. And it does mean I don't have to mess about with higher
voltages.
A bit of experiment time tonight then! 
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CNHSS1
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| posted on 27/12/13 at 05:51 PM |
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without pics I cant be sure, but I suspect they will be 'sub C' size, a little smaller than the normal C size domestic batteries. These
are probably the widest used in industrial tool applications and one of the more common in RC models.
approx. 22mm diameter and approx. 43mm long
"Racing is life, everything else, before or after, is just waiting"---Steve McQueen
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renetom
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| posted on 27/12/13 at 06:17 PM |
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drill
Hi
Having run a partitioning & suspended ceilings business since 1982
We have used every make of cordless drill , the only fault being the batteries
and nearly always cheaper to buy a new drill.
so you are left with a good drill which is unusable.
For the kit car builder , I have come up with a good idea to make use of the these
Take the battery pack apart & remove the batteries, drill a hole in the back of the pack
fit a 3m length of flex soldered to the internal terminals , re-stick the two halves together
Fit crocodile clips to other end of flex, and you have a very powerful 12V reversible
Drill which can be used out & about or if you have no power in your garage with a 12v Battery.
good luck
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RickRick
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| posted on 27/12/13 at 08:36 PM |
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"flashing" does/can work but there is a small risk of exploding cells. from using batterys in rc cars for 20+ years nicads are tough
old things but do slowly loose capacity nimh are more powerful but need very careful looking after to last more than a year LIPO are brilliant
loads of power, keep a charge when stored for a few months and last a long time, but do take care of them misuse can make them scrap! i'd
get a new lipo drill and take good care of the batterys
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nickm
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| posted on 28/12/13 at 07:51 PM |
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Might be worth sticking it in a freezer overnight works for most batteries before a re-charge
Nick N
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MikeRJ
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| posted on 28/12/13 at 09:43 PM |
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I have recovered quite a few NiCd cells like this. However, in my experience cells that have been recovered like this are prone to fail again in the
not too distant future.
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Slimy38
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| posted on 28/12/13 at 10:40 PM |
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quote:
Originally posted by CNHSS1
without pics I cant be sure, but I suspect they will be 'sub C' size, a little smaller than the normal C size domestic batteries. These
are probably the widest used in industrial tool applications and one of the more common in RC models.
approx. 22mm diameter and approx. 43mm long
Yep, sub C checks out, there's 12 of them to make up the 18 volts. And they seem to be supplied with solder tabs so I might just build up a new
pack instead.
quote:
Originally posted by renetom
Hi
Having run a partitioning & suspended ceilings business since 1982
We have used every make of cordless drill , the only fault being the batteries
and nearly always cheaper to buy a new drill.
so you are left with a good drill which is unusable.
For the kit car builder , I have come up with a good idea to make use of the these
Take the battery pack apart & remove the batteries, drill a hole in the back of the pack
fit a 3m length of flex soldered to the internal terminals , re-stick the two halves together
Fit crocodile clips to other end of flex, and you have a very powerful 12V reversible
Drill which can be used out & about or if you have no power in your garage with a 12v Battery.
good luck
This was my first thought, I don't need the freedom of a cordless but the fact it's a T shape means that it's really nicely balanced
(and I can't find a T shape corded, do they exist?!!!). But with it being an 18 volt drill it wouldn't be very happy running off a car
battery.
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renetom
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| posted on 29/12/13 at 07:47 AM |
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Hi
One of our 18v I converted runs fine on 12v
try it , what to loose.
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Slimy38
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| posted on 29/12/13 at 12:21 PM |
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quote:
Originally posted by renetom
Hi
One of our 18v I converted runs fine on 12v
try it , what to loose.
I'll give it a go, thanks!
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