Nickel Iron batteries

[Prajna]

In the hope that this forum is a mine of information on even the most obscure subjects I post the following:

A day or so ago I was given 20 400Ah nickel iron/edison cells that a friend was using in his solar system.

As you can see from the photo, most of the cases are broken. This transpired because his watering system broke down, the batteries overheated from lack of electrolyte and the copious amount of hydrogen produced during charging exploded.

So now I'm the proud new owner of just under 10kWh of very expensive batteries or perhaps half a ton of scrap nickel and iron.

The plan is to build new cases for the 18 of 20 that are broken - perhaps a trough with partitions for each cell - and attempt to rebuild and recondition the cells.

There is very little information on the net about this battery technology that isn't hype. I have a 1,400 page Battery Bible that has a few chapters on NiFe batteries and the OEM leaflet/manual but little other info. I'm sure it is a little optimistic but perhaps on this amazing forum someone has some real knowledge or even experience with them and might be able to give some pointers on how to, or whether it is even possible to, recover these batteries.

 

[Bullet2012]

I would think the bigger issue will be that the plates have warped when they got hot.

 

[awemawson]

Nickle / iron cells are pretty indestructible. Historically cases were sheet steel vitreous enamelled on the outside. As boys my brother and I had several ex-services banks of them that were grossly abused - massively over discharged or left for months uncharged, and they always came back to life. Far better than lead / acid.

 

[Prajna]

I'm sure they will be amazing batteries if I can get them working again. It is an excellent technology. These have been sitting in this condition - cases broken, empty of electrolyte - for quite a while now. I have heard that CO2 poisons the plates (or maybe it is just the electrolyte) and that they require a very long charge to recondition if left without electrolyte. Still got lots of research to do.

 

[MattH]

The chap is a doorknob but has gone through this himself so worth a watch:

 

[Blobber]

Nothing sensible to add but if anyone can make something from nothing im sure you can, can you just try and rebuild one into a new case and see if it works?

 

[Prajna]

The chap is a doorknob but has gone through this himself so worth a watch:

Wow, excellent info, Matt. Thanks.

 

[Prajna]

Nothing sensible to add but if anyone can make something from nothing im sure you can, can you just try and rebuild one into a new case and see if it works?

The video Matt posted leads me to be somewhat optimistic. Even if I get way less than 800Ah @ 12v it will be a major win.

 

[not done it yet]

Just use them as short term storage - they self-discharge at quite a rate. I have ten (I think) small cells. They were going to be thrown out at the local CFE about 25 years ago.

Not used them for years. I might get them out and charge them sometime when there is plenty of sunshine.

As the electrolyte is pot. hydroxide, they would absorb carbon dioxide. Need some lithium in the electrolyte for maximum efficiency I think lithium carbonate would suffice.

 

[Prajna]

Just use them as short term storage - they self-discharge at quite a rate. I have ten (I think) small cells. They were going to be thrown out at the local CFE about 25 years ago.

Not used them for years. I might get them out and charge them sometime when there is plenty of sunshine.

As the electrolyte is pot. hydroxide, they would absorb carbon dioxide. Need some lithium in the electrolyte for maximum efficiency I think lithium carbonate would suffice.

Thanks NDIY. In a solar system they'll get cycled daily pretty much, so the self discharge is not such an issue. Also it seems that the self discharge is high in the early stages and then tapers off. Here there is little load on the system at night, so that also suits NiFe, which prefers slow discharge.

Handy to know lithium carbonate is an alternative to lithium hydroxide. Thank you.