NiCd still used in cordless drills Batterys

[TinderBox (UK)]

I was just looking at the Black and Decker range of drills and they are still using Nicd Cells.

I thought they would have been using NiMh by now!

 

[Marduke]

NiCd's hold up better to abuse, trickle charging, high discharge, etc. NiMH is really to fragile for cordless tools, so they generally skipped that step in battery tech.

 

[TinderBox (UK)]

Hi.

I have dozens of NiCd and NiMh batterys and the only ones that leak or have white crystals on the positive end are NiCd battery`s

 

[half-watt]

some of the cordless power tools i own have NiCd batteries; some NiMH.

NiCd and NiMH chemistries have some characteristics in common which make either of them work well in cordless power tools. the two characteristics i'm thinking of are the relatively flat/linear characteristic discharge curve and the ability to supply lots of current.

in both of these areas (check me on this as my memory isn't too good any longer), i believe NiCd's are a bit superior to NiMH. NiCd's have a very flat characteristic discharge curve, but "fall off a cliff", so to speak, when they are nearing depletion of the charge. NiCd's can also provide a lot of current, making them ideal for a high current draw application, like something with a motor, e.g. cordless power tools.

i think both of these characteristics make up for NiCd's lower capacity as compared to similar sized NiMH batteries.

 

[Sub_Umbra]

NiCDs have been around for over one hundred years and are still used in many applications where they still work better than anything else. I use them in different sizes for a few things.

NiCDs have been in space since the late 50s or early 60s. I seriously doubt that any satellite has ever been launched equipped with NiMH cells.

 

[monkeyboy]

NiCd can be left in a discharged state for long periods of time without damage whereas NiMh cannot. I have many old NiCd batteries from 15+ years ago that still work. I have also owned many Nimh batteries from later generations that have gone dead and needed to be thrown away. The problem is that NiMh batteries should be kept above a certain voltage and when stored for long periods of time will self discharge below this level.

I don't think NiCd has a high current advantage though. I seem to remember NiCd sub C cells in old RC packs were nowhere near as high powered as current NiMh ones. There's also sanyo eneloop NiMh AA's that can take higher loads than any other AA I've seen.

 

[half-watt]

NiCd can be left in a discharged state for long periods of time without damage...I seem to remember NiCd sub C cells in old RC packs were nowhere near as high powered as current NiMh ones.

quite some years ago, i have had NiCd cells that have undergone pole reversal fr/self-discharging during long term storage. my fault. stored them fully charged.

can't comment on the specific RC packs that are being referred to. however, NiCd does possess excellent characteristics in high load (i.e. high current draw) applications due to its ability to provide large amounts of current and its characteristic relatively flat discharge curve.

by "high powered", what might(???) be meant is CAPACITY. certainly NiCd's are NOT as energy dense as NiMH cells, for instance.

 

[MrAl]

Hi there,


As some of the other posts have already alluded to, the NiMH cells are a bit more
temperamental than NiCd's. This is a bit hard to measure with new cells but requires
a long extensive test to reveal the differences. In general, the NiCd's hold up better
over time especially when the charge regime isnt exactly perfect. This is often
discussed in various places.

One of the other things about NiCd vs NiMH cells that is not talked about as often
is the very simple fact that the NiCd cell can be charged with a charging circuit
that is MUCH simpler than that required for an NiMH cell. This sometimes tips the
hat in the development phase toward sticking with NiCd's rather than moving to
the newer technology. Also, sticking with NiCd's means using a tried and proven
technology for this particular application.

The simpler charging circuit for the NiCd cell results in a lower product cost, and
that's quite an influence when trying to sell products in today's marketplace.

 

[h2xblive]

I bought a name brand cordless drill recently for cheap. Why was it so cheap? NiCad cells, 7.2 volts, and no frills.

 

[big beam]

Robust and cheap.
DON

 

[yuandrew]

I was going to make another thread about this but since we're on the subject of drill batteries, I'd figure I post here.

Anyway, both my DeWalt 12 volt batteries gave out on me; both not accepting a charge and one of my electronics teacher who had a look at one of the packs told me that I had some shorted cells in it. He did mention that I could get the pack re-celled although I have no idea where. I already gutted that particular pack of its cells and recycled them leaving me with an empty shell to work with if I want to put whatever I want in it.

Anyone re-celled their own drill batteries (either professionally or do it yourself) ?




Hmm, I wonder what would happen if I ran my drill with a 14.4 volt battery, the speed control part is rated for that voltage even though it's a 12 volt drill (I took the drill apart once; it says 14.4 volts on the item behind the trigger)

 

[LukeA]

I was going to make another thread about this but since we're on the subject of drill batteries, I'd figure I post here.

Anyway, both my DeWalt 12 volt batteries gave out on me; both not accepting a charge and one of my electronics teacher who had a look at one of the packs told me that I had some shorted cells in it. He did mention that I could get the pack re-celled although I have no idea where. I already gutted that particular pack of its cells and recycled them leaving me with an empty shell to work with if I want to put whatever I want in it.

Anyone re-celled their own drill batteries (either professionally or do it yourself) ?




Hmm, I wonder what would happen if I ran my drill with a 14.4 volt battery, the speed control part is rated for that voltage even though it's a 12 volt drill (I took the drill apart once; it says 14.4 volts on the item behind the trigger)

I was thinking about recelling the NiCDs in my Metabo PowerMaxx with 4 eneloops. Maybe when those NiCDs are no good.

 

[MrAl]

I was going to make another thread about this but since we're on the subject of drill batteries, I'd figure I post here.

Anyway, both my DeWalt 12 volt batteries gave out on me; both not accepting a charge and one of my electronics teacher who had a look at one of the packs told me that I had some shorted cells in it. He did mention that I could get the pack re-celled although I have no idea where. I already gutted that particular pack of its cells and recycled them leaving me with an empty shell to work with if I want to put whatever I want in it.

Anyone re-celled their own drill batteries (either professionally or do it yourself) ?

Hmm, I wonder what would happen if I ran my drill with a 14.4 volt battery, the speed control part is rated for that voltage even though it's a 12 volt drill (I took the drill apart once; it says 14.4 volts on the item behind the trigger)

Hi there,

I did my battery pack after TWO packs died after only 6 months! I got some
decent NiCds and redid the whole thing.

One thing that is bad to do is replace the NiCds with NiMH. The NiMH require a
different charging scheme so wont work very well with a pack that normally
charges with a NiCd type charging circuit.

I had a little trouble getting all the cells back into the pack but eventually it
worked. Have to be sure none short out or they will get hot and smoke.
In general it's not the easiest thing to do, but it does work if you are careful
about soldering the cells and making sure there is proper insulation between
cell terminals.

Oh yeah, a related topic is that i also redid my shaver, which had NiCds
(small ones). I replaced them with NiMH cells that had a much higher
rating, and wouldnt you know it, they died after about 6 months because
NiMH cells dont like to be charged continuously 24/7 like NiCds will put up
with for quite some time (at least a year) and that's the way cheap NiCd
chargers work.
This time i put a battery holder on it so that i can change them in five
seconds if the old set dies out.
6 months isnt too bad i guess, but NiMH would last a lot longer if
they had the proper charging circuit.

 

[half-watt]

[quote from fluff advertising post now deleted by moderator]

isn't a Post like the quoted Post that i'm replying to in violation of the recent explanation of CPF rules i've seen by DM51 and Empath?

don't want to report it as i'm not sure, but i think that it is. can anyone enlighten me?

 

[monkeyboy]

by "high powered", what might(???) be meant is CAPACITY. certainly NiCd's are NOT as energy dense as NiMH cells, for instance.

No, by power I mean power in watts = voltage x current. Since voltage is roughly the same for NiCd and NiMh power is proportional to current.

Capacity and energy is something completely different.

 

[half-watt]

No, by power I mean power in watts = voltage x current. Since voltage is roughly the same for NiCd and NiMh power is proportional to current.

Capacity and energy is something completely different.

you are correct capacity is very different fr/power.

however, if you're truly talking power, then NiCd's would be preferable as they have the ability to deliver more current w/less voltage sag than similar capacity NiMH's. i believe that i'm recalling this correctly and my "old-timers" is not actin' up and i'm getting these two chemistries confused.

i still think that the performance difference you have observed w/those specific RC packs was capacity related. otherwise, i don't know why similar capacity NiMH pak would outperform NiCd pak in a high current drain application (further assuming age and treatment, i.e. neither was abused in some fashion and otherwise properly cared for, of both packs were the same).

 

[monkeyboy]

i don't know why similar capacity NiMH pak would outperform NiCd pak in a high current drain application

That may be true for similar capacity batteries but you have to remember that NiMh are available in much higher capacities.

e.g.

Sanyo 3600mAh Nimh Sub C can handle up to 50A
Eneloop 2000mAh AA can handle 10A easily

I may be wrong, but to my knowledge, there are no NiCds (of any capacity) that could outperform that.

 

[half-watt]

That may be true for similar capacity batteries but you have to remember that NiMh are available in much higher capacities....

e.g.

Sanyo 3600mAh Nimh Sub C can handle up to 50A
Eneloop 2000mAh AA can handle 10A easily

I may be wrong, but to my knowledge, there are no NiCds (of any capacity) that could outperform that.

after reading your reply, i was initially confused. we seem to be jumping back and forth from capacity (my initial point) to power (your point of contention) and then back to capacity in your latest reply to me which is quoted above. sorry, i wasn't clear in my prev. Post. i believe that this must be the cause of the confusion.

it seems that we are now "on the same page", so to speak, as your Post to which i am replying is saying precisely what i've been attempting to explain, but failing to do so obviously - fault mine.


i can't comment on your specific examples, immediately above. however, given the lower internal resistance of a NiCd cell vs. a NiMH cell, my point has been all along, WITH ALL OTHER ASPECTS IDENTICAL (i.e. comparing apples w/apples, same size, age, etc. NiCd cell to a NiMH cell), NiCd chemistry can provide more current with less voltage sag than a NiMH cell - this is a known fact of these two chemistries. now, if we compare apples to oranges (a small NiCd cell w/a larger NiMH cell), then the results of the comparison may be, and probably will be, different.

if these words still cause confusion, please re-read all of my previous Posts in this Thread for continuity in my train of thought. many thanks, pj aka half-watt

 

[monkeyboy]

now, if we compare apples to oranges (a small NiCd cell w/a larger NiMH cell)t

I'm not talking about cells of different sizes here. What I mean is: if you compare the best available NiMh cell of one size to the best available NiCd cell of the same size. (when I say best, I mean high current capability in this case.)

Surely comparing the best available cells is what's important here and not equal capacities?

EDIT: By "size" I mean dimensions.

 

[half-watt]

I'm not talking about cells of different sizes here. What I mean is: if you compare the best available NiMh cell of one size to the best available NiCd cell of the same size. (when I say best, I mean high current capability in this case.)

Surely comparing the best available cells is what's important here and not equal capacities?

EDIT: By "size" I mean dimensions.

I don't think NiCd has a high current advantage though.

Eneloop 2000mAh AA can handle 10A easily

in response to the query posed in the first quote, i would answer "yes".

the context of the second quote is a comparison w/NiMH chemistry. therefore, this second quote is incorrect. combining the second quote with the third quote reveals an easily handled 10A discharge rate. i don't know the max discharge rate of a AA Eneloop, but somewhere around twice that 10A is doable for a AA NiCd cell. it would be interesting to examine voltage sag for these two chemistries at such high discharge rates. this is a benefit of NiCd over NiMH chemistry.

referring back to the first quote, by the words "high current capability" and "high current advantage", quoted both here and above, i'm assuming that what is meant is the ability to deliver large amounts of instantaneous current and NOT the energy storage capability (i.e., capacity) of a particular cell, meaning its ability to deliver a certain level of current for a certain extended period of time. if so, then NiCd's are inherently superior to NiMH's due to the NiCd chemistry's lower internal resistance. and NiCd's would perform better in some high current drain/draw applications, viz. those that require more current than a NiMH chemistry could supply w/o excessive voltage sag. now, if one were to only draw current at a rate, even though a relatively high rate, that could be supplied by either chemistry (i.e., NiCd or NiMH) w/minimal or no voltage sag fr/the NiMH cell/battery, then the NiMH cell/battery would run/burn longer due to its greater ENERGY STORAGE capacity, not b/c it has a higher current supply capability/ability than NiCd , which it does not.

again, using somewhat different wording, all other things being equal, NiMH cells do *NOT* have a greater ability to deliver higher current levels than comparable, but lower energy storage capacity, NiCd cells.

it's just the opposite. NiCd chemistry has a greater ability to deliver higher current levels than NiMH.

this is one of the primary reasons that NiCd's are still used in cordless power tools.

if by, "high current capability", what is meant is energy storage capacity (and, i don't think that is what is meant) , then, assuming equal size, NiMH would have 40%-50% (and perhaps even a larger pct nowadays, some of my info is quite old and may have been improved upon) greater energy storage capacity as stated immediately above at the end of the prev. paragraph.

so, for a given physical battery size (i.e., three dimensional space), if maximizing current draw/delivery is critical/paramount in a design, then NiCd chemistry would still be superior to NiMH chemistry. if however, for a given physical battery size, maximizing burn/run time is more critical, then NiMH chemistry would be the way to go (versus NiCd). this is not to say that NiMH cells can't provide large amounts of instantaneous current. they can, certainly far more than alkaline chemistry, but not as much as NiCd chemistry.

NiCd's have other benefits over NiMH cells as well (e.g. it's a more robust chemistry and tolerates some types of abuse better than NiMH cells). NiMH has other advantages over NiCd as well, in addition to being less toxic to the environment (Cd does not "play nice" with the environment).

as i think about our exchange of Posts in this Thread, i think the confusion has arisen in this regard. we need to clearly define, and now, i believe we have, if we are speaking of the cell's/battery's energy storage capacity (for our purposes on CPF, generally measured in mAh), or it's maximum current delivery capacity/capability with current being typically measured in A or mA. it seems to me now that we were each thinking of a different aspect when we write "capacity" or "capability" in our Posts and we read the word "capacity"/"capability" in the others' Posts.

all this said, please know that i make no claim to being an expert on batteries in any way, shape, or form. if anything i've written here seems incorrect, then i would encourage a web search to see if, in fact, i am in error. i think that i ought to now take the time to do likewise and make sure that my memory of these things, from my school days long ago, are still clear. i believe they are, otherwise i would have already done a search myself.


perhaps an illustration is in order:

take, for example, two identical in dimensions (as well as the orientation of those three dimensions) and therefore volume, fish tanks.

[energy storage] capacity is analogous to the volume of a fish tank. it is the therefore the same in both fish tanks in this illustration.

taking the words fr/a prev. Post in this Thread, viz. "Since voltage is roughly the same for NiCd and NiMh", the voltage would be analogous to gravity and the atmospheric pressure (determined by gravity and the height of an identical column of air above the identical open top area of each tank, and the identical column starting height of water in each tank before the full tanks start to empty) which exerts its force simultaneously in the exact SAME amount upon BOTH identical fish tanks in this illustration.

lastly, the rate at which current can be supplied by the cell is analogous to a hole in the bottom of the fish tank. since NiCd chemistry has lower internal resistance than NiMH chemistry, the hole in the fish tank representing NiCd chemistry is LARGER than the hole in the bottom of the fish tank representing NiMH chemistry, thus, providing lower resistance to the flow of water out of the tank, and so, providing faster emptying of the water in the fish tank representing NiCd chemistry as compared to the smaller hole in the fish tank representing NiMH chemistry. this is analogous to the greater ability, all other things being equal, to flow current that NiCd chemistry has versus NiMH chemistry.

so, keeping the fish tank illustration in mind, and recalling the words fr/a prev. Post "No, by power I mean power in watts = voltage x current.", and combining them with these words "Since voltage is roughly the same for NiCd and NiMh", what would this tell us about each chemistry's the ability to supply current and power? the answer is obvious isn't it?

i hope that i have now finally made myself clear. if not, then i would really welcome another's assistance in communicating the differences b/t cells/batteries having these two chemistries as far as the scope of this discussion is concerned.


--------
Note: please keep in mind that when i mention internal resistance in my Posts in this Thread, that i am not speaking of that portion of a cell's internal resistance which is contributed by the quality of a cell's mechanical design or manufacture. i am speaking of that portion of a cell's total internal resistance contributed by just its chemistry and the thermal effects upon that chemistry.

since we normally discuss a cell/battery as a whole entity, it is common to just speak of "internal resistance", meaning the SUM of all the various factors that contribute to a cell's overall or total internal resistance at any point in time without breaking it down into its various parts based upon what aspect of the cell is contribution what portion to the cell's total internal resistance.