Nickel Iron Batteries

[Philip R]

Camillitech,

Unlikely those are Cad plated fasteners unless old stock. Cad plating was outlawed years ago in Europe, Guess the Chinese make them. Those look like  zinc passivated fasteners.

I stripped a dead Ever Ready C size NiCad  in my youth along with a few other types. The swiss roll plates were on a st / st grid and the paste was grey in colour, the nickel plated grid was a darker shade of grey. Definately no yellow components!!

PhilipR.

[camillitech]

Hi Philip, funnily enough that is a Chinese website right enough, maybe they plated them in the river    http://www.guardian.co.uk/environment/2012/jan/30/cadmium-spill-china-river?intcmp=122 Now you come to mention it, it is a long time since I've heard of cadmium plated bolts in the UK but they were at one time recommended for use with aluminum on fishing boats and aircraft instead of stainless steel which causes severe problems with electrolysis. That is however many moons ago 

Cheers, Paul

[desperate]

If you do chop one up here is all you need to know,

http://en.wikipedia.org/wiki/Cadmium

nice low melting point, could help with identity.

Desp

[Eleanor]

Just a thought, but something simple which may be worth doing to try and confirm the presence or absence of Iron is :

Take some of the electrolyte and add water to precipitate out whatever hydroxides are there as a result of the discharge reaction ie Nickel/Iron or Nickel/Cadmium. Separate out the precipitate and add KOH. Leave it open to the air. Any Fe(OH)₂ precipitate will go a darker green and oxidise around the surface to orange Fe(OH)₃.

Have you tried this? It doesn't require any reagents that you don't have. You have already discovered that the Hydroxides precipitate out to form a gunge when you add water. If it's lumpy you could capture a lump and add KOH solution (Just try adding some electrolyte first) until some of it starts to dissolve back into solution. Leave it in the air and this will start to oxidise any Iron II Hydroxide present around the exposed surfaces to form an orange layer. Easier and safer than chopping up batteries.

[SpeedEvil]

http://fw.bushytails.net/The_Edison_alkaline_storage_battery.pdf - may be interesting.
This is a copy of google books scan of a publication by Edison on their batteries.
It goes into construction and a little into use.

[clivejo]

Just a thought, but something simple which may be worth doing to try and confirm the presence or absence of Iron is :

Take some of the electrolyte and add water to precipitate out whatever hydroxides are there as a result of the discharge reaction ie Nickel/Iron or Nickel/Cadmium. Separate out the precipitate and add KOH. Leave it open to the air. Any Fe(OH)₂ precipitate will go a darker green and oxidise around the surface to orange Fe(OH)₃.

Have you tried this? It doesn't require any reagents that you don't have. You have already discovered that the Hydroxides precipitate out to form a gunge when you add water. If it's lumpy you could capture a lump and add KOH solution (Just try adding some electrolyte first) until some of it starts to dissolve back into solution. Leave it in the air and this will start to oxidise any Iron II Hydroxide present around the exposed surfaces to form an orange layer. Easier and safer than chopping up batteries.

I dont understand what you want me to do!

[Eleanor]

Oh dear, sorry, clear as battery gunge!

1.   Take a few ml of electrolyte out of one of the cells
2.   Add water to electrolyte to form gunge
3.   Take some more electrolyte from the cell and add to gunge until it starts to dissolve
4.   Leave in air and see if it goes orange around the edges

This isn't an exact procedure and you may need to fiddle about a bit 

Explanation

Earlier in the thread I seem to recall that you washed out one of the cells with water and ended up with loads of grey gunge? When a NiCd or NiFe battery discharges Hydroxides of whichever metals are present are formed. These are soluble in the Potassium Hydroxide solution but not in water.

I was thinking that if you take a small amount of battery electrolye it will contain the Hydroxides of Nickel and Cadmium or Iron depending on the type of battery. If you take a few ml of this and add water you should get the gunge forming. If it is a NiFe battery there should be Iron II Hydroxide in the gunge which you can test for Iron content.

I don't know what the gunge looks like - if it's lumpy you could catch a lump and put it into a small container and add a little more electrolyte (which you haven't added water to) from the battery to make it just begin to dissolve again. If it isn't lumpy just add a bit of electrolyte anyway.

In an alkaline solution (which you have created by adding the KOH in the electrolyte) any Iron II Hydroxide in the gunge will be oxidised to Iron III Hydroxide which is orange. If there's iron present it should start to happen around the edges where the gunge is in contact with the air 

[clivejo]

Earlier in the thread I seem to recall that you washed out one of the cells with water and ended up with loads of grey gunge? When a NiCd or NiFe battery discharges Hydroxides of whichever metals are present are formed. These are soluble in the Potassium Hydroxide solution but not in water.

It wasn't a gunge (something I could physically sample) , it just turned the water grey.  After a few hours it seemed to dissolve back into the water.  I think over the past 40-50 years of sitting the KOH 'fell' out of the water, or some of it did?  Ive found that by empting out half of the electrolyte, giving it a good shake and adding the electrolyte back in.  Stirring it up with a few squeezes of the SG machine, the SG comes back up to 'normal' .  It then holds a charge and doesn't need to be topped up with extra KOH.

[Eleanor]

I have taken one of the batteries (5 cells out) apart and taken the cells out its wooden crate.  The crates are old and damp, half rotten.  one of the cells feels fat and swollen of itself, I'm guessing this one is a dud.  I've emptied one into a plastic bin container and rinsed it out with rain water.  After two rinses about 750ml rain water each time, I'm still getting a grey coloured water from the cell. What is it and is it ok to leave in there?

OK, I exaggerated in referring to it as Gunge! The water is most likely to have turned grey due to the presence of Hydroxides of Nickel and Cadmium or Iron.

The crate I took was from the back so no-ones touched in it 40+ years.  The level was still over the plates.  Bit weird the grey stuff seems to be dissolving back into the liquid,  could the KOH fall out of the water over time?

The Hydroxides are insoluble in water but will dissolve in KOH which is why the grey colour disappeared again.

You can still do the Iron test I suggested even if it is just a grey solution that is formed when you add water to a small amount of electrolyte (no need to add additional electrolyte, just leave it exposed to air and see if it does anything). It would work best on a discharged battery as in a charged battery any Iron present will be on the anode and not in solution.

Something else you could do, if you still have the blue solution, is to very gently heat it in case there is a secondary reaction which needs some help 

[Outtasight]

Hi Heinz,

found this quite by accident http://tinyurl.com/LMR-NiFe probably of no interest unless you're considering new and it struck me as quite a lot of faffing about but I enjoyed the pictures.

Cheers, Paul

The owner of said NiFe bank posted a comment on my blog yesterday as he was reading about my new Lithium bank... Maybe he's reconsidering the NiFe bank now that he's had a chance to see them in action, frittering away his PV energy as they noisily convert 40% of the input power into hydrogen gas

Still, with his deep pockets, maybe a hydrogen fuel cell is next on the shopping list.

One curious set of photos on his Facebook wall showed how to configure the Morningstar TSMPPT60 that he's using to charge the "48V" NiFe bank but he then blanked out the actual charge settings from the screen grab... Like it's top secret personal data .