Nickel cadmium potentially great for off grid?

softdown · November 2020

I met an investor who bought nickel cadmium batteries for off grid solar. Said they are not available in the US - only through Japan - and very expensive. I have not studied nickel cadmium but there are several issues with lithium:
1) Plates (deteriorates) when fully charged. We are exhorted to store them at ~ 40% - 60% charge.
2) Rapid charge deteriorates them.
3) Poor performance in cold weather.
4) Charging when freezing destroys them.
5) Two weeks, or more, of storage while stone dead basically kills them.

Being a tool junkie I bought a Delta nickel cadmium drill, at least 13 years ago, and forgot about it. Pulled it out this year and charged it up. Seems fine. Kind of impressed with that. But not sure how the Japanese addressed the memory issue with cadmium.

I remember one forum poster who spoke highly of cadmium for solar - that was years ago.

BB. · November 2020

NiCad had been a popular rechargeable battery chemistry... Much more rugged and harder to damage than most tech. Was used in some aircraft because of the high current and fast recharging capabilities decades ago.

The big push to ban Cadmium because of it is a heavy metal and was responsible for a fair number of poisonings (one was when used as a plating material--Refrigerator shelving as an example, and folks use old shelf on a fire as a grill--And got sick (and died?) from cadmium poisoning.

And now, not easy to dispose/recycle cadmium anymore.

The memory issue was mostly a problem with satellites--In orbit they had very exact charging and discharging times/AH cycles that were pretty much identical (orbital and sun position, shading from earth). With hundreds of identical cycles, there was a point where the discharged/charged material formed a layer. And the uncycled material formed large grains (and less surface area). And if the discharge went past the other 100's of cycles, the voltage/current output depressed and the electronics/loads failed to operate.

https://en.wikipedia.org/wiki/Memory_effect

-Bill

mike95490 · November 2020

NiFe batteries are actually more bullet proof then NiCad, and use the same charge settings. But they may be less efficient when recharging - I never looked up NiCad efficency. NiFe is about 70%, FLA is 80%, AGM 90%, LFP is 96%. So it depends on how large you want to grow your array too. NiFe pretty much won't freeze until after you are an icicle, and the electrolyte is pretty much the same as NiCad.

softdown · November 2020

mike95490 said:

NiFe batteries are actually more bullet proof then NiCad, and use the same charge settings. But they may be less efficient when recharging - I never looked up NiCad efficency. NiFe is about 70%, FLA is 80%, AGM 90%, LFP is 96%. So it depends on how large you want to grow your array too. NiFe pretty much won't freeze until after you are an icicle, and the electrolyte is pretty much the same as NiCad.

I've wanted to revisit nickel plated iron batteries for a long time. Seems there is only one big manufacturer and they seem to be plagued with quality control issues.

They use alkalinity instead of acidity for their electrolyte. That poses safety concerns with a populace that apparently requires owners manuals that implores them to not drink the acid in the batteries.

Combining acids and alkaline's is really quite exciting. To be avoided unless it is excitement, and health issues, that one seeks.

Nickel cadmium potentially great for off grid?

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