General > General Technical Chat
Hazards of Alkaline Batteries?
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NiHaoMike:
The most common failure mode for NiCd batteries is the self discharge increasing to the point they do not hold a charge for long. In applications where they're constantly being trickle charged, they do tend to last a very long time.

Lithium ion batteries also tend to last "forever" if not abused, although the internal resistance increases over time. The oldest one in my collection is about 20-25 years old and still works great powering a solar charged flashlight.
james_s:

--- Quote from: Boris_yo on October 25, 2021, 02:35:35 am ---I still have cordless screwdriver / drill set from 2011 that works on NiCAD batteries and use it rarely. I wonder if NiCADs degrade over time in a discharged state and not being used and if they start releasing unhealthy fumes and leak...

--- End quote ---

They certainly do degrade over time, and it's possible for them to leak but the leaked electrolyte is similar to that used in the alkaline batteries. NiCd cells do contain cadmium which is fairly toxic but it is a metal and won't be leaking out.
Siwastaja:
If you see NiCd cells that leak, I would be careful with them. Even though the cadmium shouldn't leak out, it's quite toxic even in small amounts. So just in case, use disposable gloves, put cells in plastic bags, wash hands, get them recycled properly.

But even leaked NiCd cells are't going to pollute the air with cadmium dust.
David Hess:

--- Quote from: NiHaoMike on October 25, 2021, 02:49:48 am ---The most common failure mode for NiCd batteries is the self discharge increasing to the point they do not hold a charge for long. In applications where they're constantly being trickle charged, they do tend to last a very long time.
--- End quote ---

Dendrites form which eventually puncture the separator and short out the cell.  High temperature and low leakage NiCd cells have a thicker separator, reducing capacity, but being tougher they last longer.

I finally gave up on my old set of cordless tools because it was less expensive to buy new lithium battery based cordless tools than to replace the old NiCd batteries, although I could still do that.
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