Nickel Iron batteries

[Oldgreybeard]

I wonder how efficient a large NiFe battery could be when linked to WT farm or a massively oversized household alarm array, given cost implications of lithium. What is the C value anyway, 0.2 like with lead acid?

Although looking at those calls you'd need to design an space efficient and ergonomic access arrangemt which would not be simple...

The NiFe packs I had could deliver a massive amount of current, at least 5C, maybe more. Same for charging. They were built as ground power packs for starting aircraft. The cells were metal cased Edison NiFe cells, encased in hardwood cages, and had originally been fitted inside an aircraft ground power trolley. IIRC, mine were used as Griffon starter packs originally, for starting Lancaster engines.

[midwesteddie]

@deanforest, did you ever get a reply regarding purity? I suspect I'm due for an electrolyte change soon too and feeling very intimidated about it. I'm in the US, but I did not build my system. It was already installed when we purchased this house. I am very concerned about disposal of the old electrolyte and sourcing and making the new electrolyte.

Any assistance would be great!
Ed

[Stinsy]

@deanforest, did you ever get a reply regarding purity? I suspect I'm due for an electrolyte change soon too and feeling very intimidated about it. I'm in the US, but I did not build my system. It was already installed when we purchased this house. I am very concerned about disposal of the old electrolyte and sourcing and making the new electrolyte.

Any assistance would be great!
Ed

What makes you think your electrolyte needs changing? You do need to top up with distilled water but the batteries should last 100 years or more without an electrolyte change!

[Colin Deng]

Purely out of interest, what is the typical discharge rate for LiFePO? I wonder what it would be like to try and use 2 battery arrays and what such a system would even look like...

Self discharge rate of LiFePO4 is 1-2% per month.

Self discharge rate of NiFe is 1-2% per day.

Self discharge rate of LiFePO4 will be 3-5% per month according to the data sheet of the battery
The sodium-ion battery self discharge rate is 3%

[Oliver90owner]

I changed the electrolyte in some cells about 30 years ago. Their self discharge rate was rather higher than 2%/day as I recall.

Relatively small cells, which reside in the back of a deep shelf in my garage. My last check of them was some (several!) years ago and I put them back on the shelf. As I recall the electrolyte included some lithium hydroxide, too.

These cells were old when I got them - they were to be disposed of at the college, so I took them home.

This thread may prompt me to get them out again. I suspect the electrolyte may well be all pot carbonate by now.

I suppose I might need to drain the electrolyte, evaporate to dryness, then heat strongly to dissociate the carbonate, to K2^O and CO2, and then redissolve the residue in water. I have some KOH (if that has not been carbonated, by now) but no LiOH.