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Old 8th Aug 2018, 5:39 pm   #1
beamcurrent
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Default Nickel Cadmium vented cell battery, advice sought

I have recovered this battery from a dark corner were it has lain unused for 20 years. It is a 24volt battery of about 20Ah., made from cells recovered from an aircraft battery, now in a stout wooden box.

Now my first thought was to dispose of it, but it's rather nice really. It will need some sorting out, none of the cells are short circuit.

But I am worried about the electrolyte levels which can be seen through the cell walls and the vent plug.

Some cells seem to have more electrolyte than I would expect and some much less. None of the cells appear to leak.

Question; Is there any reason why the levels are so different between cells, I expect they were more or less correct when last used, and can I just transfer the excess to the cells with a deficit?

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Old 8th Aug 2018, 5:52 pm   #2
The Philpott
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Default Re: Nickle Cadmium vented cell battery, advice sought

It is said that no discernable changes occur in the electrolyte (30% solution of Potassium Hydroxide in Distilled Water) whether charged, part charged, or discharged. So if you can get hold of KOH somewhere this would be the best solution (pun not intended)

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Old 8th Aug 2018, 6:31 pm   #3
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Default Re: Nickle Cadmium vented cell battery, advice sought

Is it likely that any electrolyte has been lost, through inversion/leakage?
If not then a simple water top up and hydrometer test might be all that is needed.

I suppose you could empty the lot and start again fresh. Do these cells drop crud from the plates like lead acid? Pardon my ignorance.

I had a small 2Ah one once, it could deliver one hell of a lot of current. Ejected from my bedroom window into the front garden because of smoke emissions.

A shortcoming in the insulation of my charging system had become manifest...

Last edited by Jon_G4MDC; 8th Aug 2018 at 6:35 pm. Reason: boo-boo
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Old 8th Aug 2018, 6:36 pm   #4
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Default Re: Nickle Cadmium vented cell battery, advice sought

No personal experience, but I have a 1940's book on battery charging that covers both NiFe and NiCd batteries. For NiCds, as well as periodic topping up with distilled water to compensate for evaporation, total replacement of the electrolyte was recommended once a year, as indicated by the normal S.G. of the electrolyte dropping from 1.19 when fresh , to 1.16. The deterioration was said to be due to reaction between the Potassium Hydroxide of the electrolyte with atmospheric Carbon Dioxide, producing highly soluble Potassium Bicarbonate.

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Old 8th Aug 2018, 6:40 pm   #5
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Default Re: Nickle Cadmium vented cell battery, advice sought

Thanks Emeritus for resetting my memory.

Mine was a NiFe battery after all. It seemed to be cells set in a clear Epoxy casework with receptacles in the top to accept a two pin plug. I think it had a broad arrow.

I wonder what happened to it. I want it back!

Last edited by Jon_G4MDC; 8th Aug 2018 at 6:42 pm. Reason: added recall
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Old 9th Aug 2018, 9:14 am   #6
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Default Re: Nickel Cadmium vented cell battery, advice sought

Quote:
Originally Posted by beamcurrent View Post
I have recovered this battery from a dark corner were it has lain unused for 20 years. It is a 24volt battery of about 20Ah., made from cells recovered from an aircraft battery, now in a stout wooden box.

Now my first thought was to dispose of it, but it's rather nice really. It will need some sorting out, none of the cells are short circuit.

But I am worried about the electrolyte levels which can be seen through the cell walls and the vent plug.

Some cells seem to have more electrolyte than I would expect and some much less. None of the cells appear to leak.

Question; Is there any reason why the levels are so different between cells, I expect they were more or less correct when last used, and can I just transfer the excess to the cells with a deficit?

Regards

Brian
Brian, Are you sure this is not a NiFe battery? If it is don't put any acid in it.
Some cells may have deteriorated quicker than others, a bit like nicad batteries do, resulting in an imbalance in charge efficiency, causing some cells to over charge and loose electrolyte.
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Old 9th Aug 2018, 10:22 am   #7
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Default Re: Nickel Cadmium vented cell battery, advice sought

This has been an education as I had never heard of NiFe cells before and a quick Google has been interesting
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Old 9th Aug 2018, 11:14 am   #8
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Default Re: Nickel Cadmium vented cell battery, advice sought

Thanks for the replies. Attached is a picture of the Ni-Cad battery and you can see the differences in level especially the second cell from the left is much higher that the others. My concern was how it got to be this high level.

The right most one may have a leak as I can't see any electrolyte in it? I think I will have to take it apart to see. This may be awhile before it makes it to the top of the to-do list. Fortunately I have some spare cells from the original build back in the 1980s!

It may be of interest to know that this was the standby lighting battery in my vintage OB van and has come to attention because we plan to restore the van to it's original condition see the partially written website. www.mcr21.org.uk

When It comes to charging I do have a clever "PAG" multi function charger that claims to restore batteries, we'll see.
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Old 9th Aug 2018, 2:01 pm   #9
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Default Re: Nickel Cadmium vented cell battery, advice sought

I have some similar sort of Ni-Cads to these, but have not really done much with them. They were working Ok when last checked but that was a year or two ago.
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Old 9th Aug 2018, 4:00 pm   #10
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Default Re: Nickel Cadmium vented cell battery, advice sought

I used some of these, ex-military NiCads, years ago. Note that the electrolyte is alkaline, not acid. And highly corrosive to human skin.

They would take a hell of a bashing, electrically speaking, I used to charge them at c/10 and discharge at several amps if required. They were used to power radio channel monitoring equipment at model aircraft displays and for charging 'c' size NiCads for electric model aeroplanes.
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Old 9th Aug 2018, 4:22 pm   #11
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Default Re: Nickel Cadmium vented cell battery, advice sought

They look like NiFe cells to me. The originals had metal cases and they go back to the early 1900's . I'm not 100% sure but I think Thomas Edison might have invented or at least commercialised them. I know he had an electric car that he drove on a 1000 mile endurance course in 1915 that uses them. They were used extensively in vehicles like fork lifts in the 1960's.

I have a few NiFe cells in vintage marine lanterns, They are the wet electrolyte equivalent of the NiCad, in the analogous manner that the wet Leclanché cell is the equivalent of the dry zinc carbon torch cell of today, except of course the NIFE/NiCad are rechargeable.

In any case, to get them up and running I would replace the KOH electrolyte.

Beware of this though: Alkalais like KOH or NaOH are infinitely more toxic to human tissue (skin & eyes) than acids. The reason is alkalais liquefy proteins and keep penetrating into tissues, where acids coagulate them and create a barrier. So be extremely careful of skin & eyes mixing up KOH, uses gloves and protective eyewear.
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Old 9th Aug 2018, 5:01 pm   #12
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Default Re: Nickel Cadmium vented cell battery, advice sought

Definitely agree with Argus on safety with KOH!

Potassium hydroxide (and sodium hydroxide) also turn fats and oils to soap - if you have a drop of solution on your fingers it immediately feels soapy. It is worth having a good quantity of weak acid available, to neutralise spills - cheap vinegar is fine. (Why should the acid be weak? Well, to be sure of neutralising any spills of alkali, you want an excess of acid - but if you have an excess, you want the surplus to be non-aggressive, which vinegar is. Note that weak acid is NOT the same as dilute acid; a weak acid is an acid whose molecules take a lot of persuasion to behave like an acid, such as only when attacked by a strong alkali; so when the spilled KOH is all neutralised, any remaining weak acid is relatively safe).

I have seen Edison NiFe cells very similar to the OP's photographs! I have never seen a wet NiCad like this - but I believe they existed. Construction would have been very similar and the only way of telling them apart would have been the labelling. So, the OP could have either types of chemistry, and I reckon that charging them and measuring the voltage is the only way to tell apart. I believe that NiFe has a higher self-discharge rate but it was cheaper, and also has a higher terminal voltage (around 1.5V as against 1.25V).
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Old 9th Aug 2018, 5:04 pm   #13
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Default Re: Nickel Cadmium vented cell battery, advice sought

As an aside, I have an old book (over 100 years old) that refers to the Nickel-alkaline secondary cell (I assume the NiFe cell) as the 'Edison Storage Battery'
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Old 9th Aug 2018, 5:42 pm   #14
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Default Re: Nickel Cadmium vented cell battery, advice sought

NiFe and NiCad are different technologies, although similar: https://batteryuniversity.com/index....ased_batteries
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Old 9th Aug 2018, 6:53 pm   #15
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Default Re: Nickel Cadmium vented cell battery, advice sought

NiFe has more of a chance of being serviceable than NiCd after all this time
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Old 10th Aug 2018, 10:29 am   #16
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Default Re: Nickel Cadmium vented cell battery, advice sought

Weren't NiFe cells what powered milk floats?
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Old 10th Aug 2018, 11:16 am   #17
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Default Re: Nickel Cadmium vented cell battery, advice sought

I have managed to dig out the copy of the SAFT Engineers' Handbook for Nickel-Cadmium batteries that I acquired at an exhibition in 1988 (30 years ago: time has flown!) and have scanned some relevant extracts relating to open cell batteries. Things had obviously moved on since the 1940's.

No longer recommended to change the electrolyte every couple of years, now only necessary to top up with fresh electrolyte if the S.G. gets too low. Topping-up with distilled water normally only required every 2 to 3 years if the specified charging regimes are followed, but may be needed every few months if the battery is worked hard. No mention of deterioration of electrolyte in the cell itself due to reaction with Carbon Dioxide: only the possible need to remove the thin layer of Potassium Carbonate that might form on the cell covers. Any possible fall in the specific gravity of the electrolyte is attributed to electrolyte having been carried away as a vapour when cells are gassing during charging. Possibly improved vent design now prevents ingress of CO2?

When putting into service after a long period of disuse, two cycles of charge and discharge (to 0V per cell) is recommended.

The efficiency (energy out to energy in) should be around 70%.
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Old 10th Aug 2018, 11:50 am   #18
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Default Re: Nickel Cadmium vented cell battery, advice sought

On re-reading the original post I note that the cells were for use in aircraft. The SAFT handbook has a special section for this type of battery, scan attached. It indicates on the last page that they should be capable of being brought back into service after long periods of storage, regardless of their state of charge when last used.
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Old 10th Aug 2018, 12:14 pm   #19
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Default Re: Nickel Cadmium vented cell battery, advice sought

British delivery vehicles tended to use lead-acid batteries, but the famous Harrod's vans used Edison (NiFe) batteries.
The NiFe battery is very robust. It will take short-circuits without permanent damage.
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Old 10th Aug 2018, 8:40 pm   #20
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Default Re: Nickel Cadmium vented cell battery, advice sought

The PDF on Aircraft batteries looks most useful. The "list of things that must be done", has kept me away from the batteries but I will read the PDF & return to the battery job next week. If I survive the rain promised for the Flight Refueling Rally.

Thanks for posting it emeritus

Brian.
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