Is there any reason to use NiCad cells nowdays? Do they handle high discharge rates better than NiMh? The reason I am asking is because I can get NiCad cells easily in my town, but good NiMh are hard to come by. I was going to run them in a 2D-6AA holder to power the 5761 bulb. I have to drive to Macon (60 miles away) to get eneloops.
NiCad or NiMh?
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Marduke
Flashaholic
You can order NiMH online ya know.
Brighteyez
Flashlight Enthusiast
That's an odd situation. It's almost impossible to find NiCD batteries in a most retail stores these days. NiCDs have traditionally been able to handle high discharge rates and abuse pretty well, though their limited capacity in the AA size will severely impact the runtime for your intended application. If you were going to use a 6D cell body, NiCDs would be a reasonable alternative, but in the AA size, you're looking at batteries that have a capacity of about 1 Amp at best, whereas a current NiMH battery will have double that capacity (Eneloops or other low discharge NiMH) and possibly more with the non-LSD batteries. If you have a Wal*Mart nearby, you might also want to look at the new Duracell "pre-charged" batteries as a potential for a local resource.
JNewell
Flashlight Enthusiast
Much lower self-discharge rate.
radellaf
Flashlight Enthusiast
Another reason would be lower capacity.
e.g., if you want to solar charge the cells and can't get more than 100mA or so.
e.g., if you want to solar charge the cells and can't get more than 100mA or so.
Curious_character
Flashlight Enthusiast
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NiCd cells have two advantages over NiMH: good performance at high discharge rates, and the ability to tolerate fairly long term overcharge at a 0.1C rate. The first advantage has pretty much disappeared, because a 4C, say, discharge rate of a NiCd cell is less than a 2C discharge rate of a NiMH cell of the same size. So even if the NiMH might not do as well at 4C as a NiCd at 4C, it usually does as well or better at the same actual current.
The second advantage allows the use of very simple chargers with NiCd cells, while NiMH cells require smarter chargers for long life. So I believe some currently produced battery powered items like vacuums, razors, and tools, still use NiCd because of the simplicity and low cost of the charger. I use NiCd to replace cells in these and older appliances when they fail.
Because of the ability to tolerate overcharge, I also use NiCd cells in conjunction with a solar panel. A solar panel is essentially a constant current source, so if the maximum panel output of the panel is 0.1C or less (e.g., 100 mA when using 1 Ah cells), the panel can be connected directly to the battery without any regulation at all or worry about damaging overcharge. Realistically, even NiCd cells don't like a constant 0.1C charge for extremely long times, but they can tolerate it a whole lot better than NiMH cells can.
Cadmium is toxic, so it's particularly important to recycle NiCd cells rather than dumping them into a landfill.
c_c
The second advantage allows the use of very simple chargers with NiCd cells, while NiMH cells require smarter chargers for long life. So I believe some currently produced battery powered items like vacuums, razors, and tools, still use NiCd because of the simplicity and low cost of the charger. I use NiCd to replace cells in these and older appliances when they fail.
Because of the ability to tolerate overcharge, I also use NiCd cells in conjunction with a solar panel. A solar panel is essentially a constant current source, so if the maximum panel output of the panel is 0.1C or less (e.g., 100 mA when using 1 Ah cells), the panel can be connected directly to the battery without any regulation at all or worry about damaging overcharge. Realistically, even NiCd cells don't like a constant 0.1C charge for extremely long times, but they can tolerate it a whole lot better than NiMH cells can.
Cadmium is toxic, so it's particularly important to recycle NiCd cells rather than dumping them into a landfill.
c_c
mdocod
Flashaholic
ever owned a Ryobi 18V NiCD tool? self-discharges in a few weeks... I hear a lot of people tout NiCD for having better self-discharge characteristics, I haven't seen much evidence that it's true... I think some cells are better than others at holding a charge, and it has very little to do with whether it's NiCD or NiMH. they could probably make cells that share similar characteristics with NIMH LSD cells in a cadmium version...
I like to buy from B&M stores as much as possible, plus, if I killed the cheap NiCads from high current it wouldn't be as bad as killing Eneloops. If I understand correctly, using 2000mah Eneloops to power the 5761 bulb at 7.2V would significantly shorten their life. If it doesn't kill them to fast I might just use the Eneloops in the first place...
Illumination
Flashlight Enthusiast
NiCad is also incredibly toxic for the environment - making them and disposing them.
They are all made in china now - so lots of unfortunate Chinese get nasty diseases because there are really bad environmental regs in China (see the article about this in the Wall Street Journal)
If Nicads get into landfil, they will leach nasty toxins into the environment.
Nimh is supposed to be much less of a problem.
They are all made in china now - so lots of unfortunate Chinese get nasty diseases because there are really bad environmental regs in China (see the article about this in the Wall Street Journal)
If Nicads get into landfil, they will leach nasty toxins into the environment.
Nimh is supposed to be much less of a problem.
TorchBoy
Flashlight Enthusiast
Don't think it's a Ryobi branded one, but Yes! :scowl: What to do about it?
Sub_Umbra
Flashlight Enthusiast
I don't think that anyone has mentioned that NiCDs operate over a wider temperature range at their rated capacity than NiMH.
We use NiCDs in a number of applications ranging from Cs in very bright emergency lights to AAs in body mics.
We currently have a FIFO box (first in, first out) for the body mic AAs. It's a little tupperware type box fitted with a chunk of foam with fifteen holes drilled into it. It is designed to hold fourteen cells so with an empty hole the sound men always know which cell to use next. The cells are always taken for use in the same direction by the sound techs and when they come out of the mics they go back into the box in the same holes -- but with the positive end up. It works very well. Mrs Umbra just takes the box home once a week and I service the cells that have been used and put them back in place so the oldest will always be used first when they go back to the club. Aside from being very organized the box also gives the cells a great deal of protection as they're not rolling around and getting damaged between shows.
Even though the cells are only 1,000 mAH they do a great job in the mics and have far more runtime than is required. The number of cells in the box means that for an average week less than half of them will be used -- although there are enough cells to power all the mics needed for the exceptional weeks, like the holidays we just went through.
The sound men are totally on board with the NiCDs and the performance of the cells has been flawless. They're very cheap, they work well in the mics and with good chargers they should last a very long time -- years and years. I haven't had to dispose of any yet but Rat Shack has taken the few NiCDs I've had to toss over the years.
I'm sure that some would think that NiMH cells would work just as well but I would not use them in that application. I don't need twice the capacity. I need RELIABILITY and NiCD cells are perfect for us -- aside from saving beaucoup bucks over their projected lifetime. It is also great (from the Club's point of view) to never run out of cells and to never have to take someone on the payroll away from what they're doing to drive a 2,500 pound car somewhere to pick up some AAs at the last minute.
I'm sure that there are other ways to do it but NiCDs are perfect for us for body mics and a number of other specific uses. I have fewer NiCDs than NiMHs but they're properties are different enough that they each have their place.
We use NiCDs in a number of applications ranging from Cs in very bright emergency lights to AAs in body mics.
We currently have a FIFO box (first in, first out) for the body mic AAs. It's a little tupperware type box fitted with a chunk of foam with fifteen holes drilled into it. It is designed to hold fourteen cells so with an empty hole the sound men always know which cell to use next. The cells are always taken for use in the same direction by the sound techs and when they come out of the mics they go back into the box in the same holes -- but with the positive end up. It works very well. Mrs Umbra just takes the box home once a week and I service the cells that have been used and put them back in place so the oldest will always be used first when they go back to the club. Aside from being very organized the box also gives the cells a great deal of protection as they're not rolling around and getting damaged between shows.
Even though the cells are only 1,000 mAH they do a great job in the mics and have far more runtime than is required. The number of cells in the box means that for an average week less than half of them will be used -- although there are enough cells to power all the mics needed for the exceptional weeks, like the holidays we just went through.
The sound men are totally on board with the NiCDs and the performance of the cells has been flawless. They're very cheap, they work well in the mics and with good chargers they should last a very long time -- years and years. I haven't had to dispose of any yet but Rat Shack has taken the few NiCDs I've had to toss over the years.
I'm sure that some would think that NiMH cells would work just as well but I would not use them in that application. I don't need twice the capacity. I need RELIABILITY and NiCD cells are perfect for us -- aside from saving beaucoup bucks over their projected lifetime. It is also great (from the Club's point of view) to never run out of cells and to never have to take someone on the payroll away from what they're doing to drive a 2,500 pound car somewhere to pick up some AAs at the last minute.
I'm sure that there are other ways to do it but NiCDs are perfect for us for body mics and a number of other specific uses. I have fewer NiCDs than NiMHs but they're properties are different enough that they each have their place.
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