Nickel Iron Batteries real data

[paulvk]

I have just got a set of Nickel Iron cells for my 48v off grid setup and
as there is very little real data from people using them and a lot of negative comments
largely by people who do not have them or are selling other battery tech I am going to put
real facts good and bad here so real life use can be recorded.

First observations from simply charging and testing the cells as they are almost new 200Ah:

Gassing was less than expected charging with 20 amps then going to 16 amps at 1.65 volts per cell left for 4 hours
Note less gassing than flooded lead acid at near same capacity 225Ah

Self discharge appears less than expected they were all at 1.3v or above and had been sitting for very long time before I got them
and after above charge still at 14.2 for a bank of ten week later

Load test after fresh charge 55 amps draw voltage dropped to 1.21 per cell

Watering : the cells 37 of them took 12 liters of water this filled them from just above the minimum to just below maximum line

Will do a discharge test when I have time to set up timers and cut offs.

Regards Paul

[moose4621]

Interesting observations there Paul.

There certainly seems to be some misconceptions about nickel/iron batteries in the web, and as you say, mostly from people with no experience with them.

I have just installed a 48v 300a/h nickel/iron pack to replace a 1380a/h lead/acid pack in a stand alone domestic power supply.
So far, everything is going well and my observations are identical to yours.

Many of the so called negative attributes of nickel/iron are largely of no concern in a stand alone solar system too.
Things like:

• they have a low energy density. This is true but the 300ah pack I have just installed gives me the same useable capacity as a 1380ah lead/acid because of the severe restrictions on lead acid depth of discharge and so the energy density of the two packs are comparable.

• They have a high self discharge. Possibly true. But who cares! They are being charged by solar every day.

• They have poor charge efficiency. Comparitively, yes they are not quite as good as lead/acid but at around 80%, a few extra panels are cheap.

And so on and so forth.

The greatest advantage to me, was the price. Both initial purchase price and running costs. Having purchased the 1380ah lead acid pack 13 years ago for around $14000, and then being faced with a $24000 bill to replace them with the same again, I was imagining what the price would be in another 13 years!
The Nickel/Irons are reportedly lifetime batteries requiring new electrolyte worth a few hundred dollars every 8-10 years. It's a no brainer financially. That's if they do the job.

Like you Paul, I am keen to get some real experience with these and post the results as there is a severe lack of real information on line.
I look forward to hearing about your experience with them.

[antiscab]

out of curiosity, what did the nickel iron batteries cost?

[paulvk]

They seem to average $1 per Ah per cell of 1.2V I got my ones second hand for half that.

[weber]

Thanks paulvk. I look forward to your data.

Reading this thread so far, was like stepping back in time. Not because you're talking about NiFe cells, but because you're only comparing them to lead-acid.

[paulvk]

Thanks paulvk. I look forward to your data.

Reading this thread so far, was like stepping back in time. Not because you're talking about NiFe cells, but because you're only comparing them to lead-acid.

Its like oranges and apples they a flooded cells, bulky (more bulky than lead acid) , heavy and emit hydrogen & oxygen gas so they can not be compared to other technology where space and weight is of concern so in off grid these are not usually a problem then trying to compare them to lithium would also be problematic as its their extremely long life maybe longer than the owner , ability to handle abuse and infinite number of cycles (just need new electrolyte)

They may also work with EV charging storing energy during the day or off peak and charging the EV at night.

This thread may take years just like the PIPs

[jonescg]

Looking forward to watching this unfold. Care to share a photo or two of the NiFe cells?

They aren't cheaper than most chemistries, that's for sure. But the longevity sure puts them in good stead for the likes of remote roadhouses etc.

[paulvk]

This is the type I have but 200Ah not 400Ah and only two terminal posts not four
[image=]

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[/image]

[T1 Terry]

Are you using potassium hydroxide or lithium hydroxide in these batteries? Have either of you tried both electrolytes to see what advantages one has over the other?
Is charge control based more on electrolyte temperature than voltage?

Looking forward to reading the information you gather from using these batteries as house power supply and storage

T1 Terry

[dRdoS7]

Hi,

Are you using potassium hydroxide or lithium hydroxide in these batteries? Have either of you tried both electrolytes to see what advantages one has over the other?
Is charge control based more on electrolyte temperature than voltage?

Looking forward to reading the information you gather from using these batteries as house power supply and storage

T1 Terry

KOH is the electrolyte used, but LiOH is sometimes added, can't remember why. None in my NiFes.

I'll be interested in hearing others comments WRT to NiFes. How are you making distilled water? How often/how much water are they using.

I installed my 48V 200Ahx40 batteries in 2016, and happy with them. Except.... I have had a couple of duds in the last 3 months. Waiting to return home from our trip, then will replace the electrolyte (seller is sending some KOH) see if that fixes them, or get them replaced.

Mine took a while before they were working to capacity. Then, they were better than the 260Ah AGMs (about 4 years) I had before. Even better once I added another 4.2kW of panels, to the existing 3kW, in 2018.

I use the same charge regime as for AGMs, Bulk/Absorb/Float, just have higher voltage settings. I work on about 75% efficiency, going by Ah in vs Ah out, measured by my meter, over about 12 months usage.

dRdoS7

[jonescg]

LiOH does work better than KOH apparently.

[dRdoS7]

LiOH does work better than KOH apparently.

I've only read of using that in addition to, never as a replacement.

https://en.wikipedia.org/wiki/Nickel%E2 ... on_battery

Do you have a link?

I did find this:

https://en.wikipedia.org/wiki/Talk:Nick ... lectrolyte

dRdoS7

[weber]

Yeah the LiOH is only an additive. Edison's patents mention 2% by weight. Here's a modern recipe:
http://nickelcells.com/pdf/manuf/Taihan ... attery.pdf
It's 20 g of LiOH and either 333 g or 313 g (it's hard to tell which) of KOH per litre (998 g) of distilled water. So about 1:16 LiOH to KOH by weight.
There's a post here that implies about 1:14. https://www.fieldlines.com/index.php?topic=135792.0
No one seems to know how the LiOH works. It just seems to be "magic sauce all make better".

[jonescg]

The lithium ion is smaller, and presumably more mobile than potassium ions, but if that's the case, why then not use entirely LiOH? Cost perhaps? Diminishing returns?

[paulvk]

Lithium hydroxide is added to reduce gassing and helps reduce the internal resistance.
As far as water is concerned there are a number of filter systems available with an osmotic filter creating very pure water
there are also stills available that produce 20L per hour could be run when the sun is up.

[moose4621]

As far as water is concerned there are a number of filter systems available with an osmotic filter creating very pure water

I exclusively used de-ironized water for the lead acids and was planning on using the same for the NiFe's.
I have a still, (ahem, water purification system ), but with a copper head it produces a desirable flavour for "beverages" but of course that indicates it is no longer pure liquid.

[weber]

The lithium ion is smaller, and presumably more mobile than potassium ions, but if that's the case, why then not use entirely LiOH? Cost perhaps? Diminishing returns?

I believe the reason is diminishing returns, not cost. Yes the bare lithium ion is smaller, but a funny thing happens in solution. The potassium ion is actually more mobile. That's because the lithium ion ends up dragging a bigger retinue of water molecules along with it, because it has a stronger attraction for them. Hydrated radius or Stokes radius actually decreases as you go down the column of the periodic table. So sodium is intermediate in mobility between lithium and potassium, as you would expect.

But even stranger things can happen when these alkali-metal ions intercalate into graphite or transition-metal oxide crystals (which doesn't happen in NiFe cells but does in Li-ion cells). So-called Van der Waals forces can produce a situation where either lithium or potassium will work just fine, but sodium will not, even though it's between them in the periodic table.

Lithium hydroxide is added to reduce gassing and helps reduce the internal resistance.

It is also claimed (by Edison, no less) to increase the capacity and extend the life.

[paulvk]

Have now made the battery enclosure and installed the cells in it.
I will take a picture when I have cleaned up , a big rearrangement was needed to make space for them
I purchased 4 more new cells to bring the number to 41
I have connected 36 cells in parallel with the lead acid banks as an experiment
36 cells at 56.6 volts gives 1.57 volts per cell getting close to the 1.6 volts for charging
Its only been two days but they have been providing 20% to 30% of load as the voltage drops on the lead acid
There is one new cell in the 36 it gasses very little compared to the older ones
One older cell has had its electrolyte changed it had a cracked case and I repaired it with an epoxy filler time will tell on this repair
I will let the system run for a couple of weeks cycling the cells I will then put the repaired cell in with its new electrolyte to see how much it gases.

The cells measured 1.3 volts even though they had been sitting for a number of weeks self discharge may not be as high as many claim who do not own them.

Right now they are at 49.5v 1.375v per cell providing about 4 amps so close to 200 watts of the 650 watts total this is much better than I expected with just 36 cells.

Regards Paul

[dRdoS7]

Hi,

Have now made the battery enclosure and installed the cells in it.
I will take a picture when I have cleaned up , a big rearrangement was needed to make space for them

I bought open shelving for mine, and then made sides tops, & doors to suit. Bolted to wall. Cupboard on the far right housed the original 4 x 260Ah AGMs, they took up a lot less space.

DSCN3421.jpg (129.28 KiB) Viewed 2904 times

DSCN3422.jpg (166.28 KiB) Viewed 2904 times

The rear groups are on raised shelves so I can see the fill lines.

The (temporary) timber supports are because I thought I was going to be supplied with smaller bodied batteries, which were to be spread over the 3 shelves in each cupboard. I ended up with larger ones, but at least they hold more electrolyte. So, less top ups required. I may make metal supports, one day, or raise them all on full width timber, so it spans the side bars, and doesn't rely on the shelving so much.

One older cell has had its electrolyte changed it had a cracked case and I repaired it with an epoxy filler time will tell on this repair
I will let the system run for a couple of weeks cycling the cells I will then put the repaired cell in with its new electrolyte to see how much it gases.

I finally received the KOH from my supplier, and have done 1 first, put in last week, then yesterday another 2, which I put in this morning. I have 6 bad ones out of 40. Took a lot of flushing to get them clear of gunk laying in the bottom. In a couple I think it was shorting them out, as they were 0.0000V when discharged (good ones still > 1.1V). They seemed to be charging OK, but discharged very quickly relative to the others.

I have noticed that once discharging, once the 1st refurb'd one is > 1.18V (total bank about 44V) that it drops rapidly to 0.65V, then when the bank is at 40.3V it's reading -0.23V. Others are around 1.17V.

I am running only 37 ATM, initially so I could remove the 3 worst batteries. Now, so I can charge them to 1.71V to get the refurb'd ones up and working properly (I hope). Using a lot of water though. Once they don't drop off the cliff, I'll revert to my normal charge settings. I'll do the remaining 3 after Christmas.

I'll be interested to read what voltages you get from the repaired & refilled battery.

dRdoS7

[paulvk]

You have the same cells as my old ones the 4 new ones are translucent white much more difficult to see the level of the electrolyte
The new ones have the max fill level 20 mm from top of case I actually think the others can be filled higher
Note both external dimensions the same.
My enclosure is steel front sides , concrete floor , plywood wall at back and steel racks
18 cells in the bottom on wheels roll out to to work on top 18 3 rows like yours top row of 5 small stool or ladder
I want what I have on my 8 lead acid batteries central watering but it is very expensive more than it should be
so I am going to look at 3D printing but have not the time at present to learn the software
Both cells old and new have the same caps.
All the cells when I got them were 1.3v or more even though they had been sitting around for a long time
Fun mixing the KOH I did it in a bucket in the laundry tub as a water bath worked well and kept it cool
for a big mixing I think breathing mask would be good alternately Saft nickel cadmium use the same electrolyte
and they have it mixed but I do not know the cost.
I will be finding out the cost of 200L of water autobarn sells 10L containers and now bunnings has 5L with their car batteries
have not seen anybody else selling distilled water only de-ionized.
Be good if you post how yours perform I have designed a board with 12bit 12 input ADC and will make up another
to expand the 12 to 47 to measure every cell
A board is measuring the current in 11 banks of my lead acid it gives 4 digit readings so can measure cell voltage to 1.xxx volts

Regards Paul

[dRdoS7]

Hi,

We had NiFe brand (I think owned by Saft later) NiCd cells at work. They were due for replacement, and I was hoping to get them, but I retired before it happened. They were still going strong after about 30 years in the basement. Spent most of their life in Float, probably tested more often than actually used. Ended up buying the same as yours a few years later.

I was looking for a suitable fill system too, read that you can't use a LA system, as it's no good with alkaline electrolyte. I have a 10l container with a small 12V pump, momentary switch on the hose, fills them quickly. Probably about 50 mins for all 40. Did 34 this morning, used 24l/21 days - high charge voltage: 1.71V/cell for the last week. Previous was 37 days/37 cells/23l/1.68V, so much better. Used to use gravity, then a hand pump, but current method works best.

Buying from Bunnings, Autobarn is very expensive! I did buy some for the first fill, but realised, long term, it was going to cost. 200l bulk might be OK. I run a small distiller, it does about 3.3l per run. The electricity is free (well, it will be after costs are recovered in a about 2024!). Use various sized water containers for storage (have about 120l all up). Bought a couple of 15l water containers for $13 each from Bunning recently, that size is about the best value. Actually hold 16l (a bit more if I wanted to), not too heavy to move.

I have voltmeters on each group of 10 cells (groups of 10, 9, 8 & 10 ATM with only 37 in service), that gives me an indication of any problems. Use a multimeter for individual readings.

Have to empty, flush, and refill the 3 remaining crook cells today. Hope to put them in service tomorrow, see how they end up after a month or so.

dRdoS7

[dRdoS7]

Hi,

This what is in the bottom of many of my cells:

IMG_20200115_075528_3-small.jpg (1.37 MiB) Viewed 2428 times

IMG_20200115_075512_4-small.jpg (1.25 MiB) Viewed 2428 times

19 out of 30 that I've seen. So far. Some of the back cells (10) I haven't got around to looking at.


And what happens if you don't wait for the H2 to dissipate before trying a "live" cell swap.

IMG_20200121_114807_1-smaller.jpg (947.19 KiB) Viewed 2428 times

Bucket! Is almost exactly what I said.

dRdoS7

[paulvk]

I have had some success with builders bog sealing my cell its only very slightly damp and no less electrolyte than other cells.
Now for the naked cell PVC seems to be resistant to KOH so a length of pipe big enough for it to fit in with end caps just need a good glue.
I always turn off breaker before switching anything.
My cells have some residue in them but nothing like that I rinsed the cracked one out twice and poured the new KOH out twice I put it back in as it was clean while changing glues.
Now is the black stuff potassium carbonate because its white or are we loosing iron ?

[jonescg]

And what happens if you don't wait for the H2 to dissipate before trying a "live" cell swap.

Is that illustrating the aftermath of a Hindenberg incident?!

[dRdoS7]

Hi,

I have had some success with builders bog sealing my cell its only very slightly damp and no less electrolyte than other cells.
Now for the naked cell PVC seems to be resistant to KOH so a length of pipe big enough for it to fit in with end caps just need a good glue.

So, I need to go to a where a new subdivision is being prepared? Get sewerage pipe & caps?

Only problem would be seeing the electolyte level.

I don't think I'll get it welded, as there's no guarantee it will remain OK. Also, it will probably cost $100 (going by the cost to do a waste water tank conversion for our caravan), while a new one is $200 (roughly).

I always turn off breaker before switching anything.

Normally I could bypass the inverter first, then the battery. But while doing voltage tests under load to the inverter's low cutout earlier in the week, I found my bypass relay was stuck. It wouldn't switch to grid. Rather than swap everything to grid manually, I thought I'll replace that relay later, and do the battery swap "live". I made the mistake of connecting the bypass battery poles first, then the live battery. Even then, it wouldn't have been a problem, but charging had only just finished. Expensive mistake.

I had to swap everything then, and remove the FU.

My cells have some residue in them but nothing like that I rinsed the cracked one out twice and poured the new KOH out twice I put it back in as it was clean while changing glues.

I had to rinse them lots of times. I was going to only use distilled water, but the seller said to use tap. I did that, then a final soak, and rinse with distilled. My arms were very tired after 6 cells. At least the cell in the pic was easy to clean out. Every cloud has a silver lining. Then something about lightning strikes comes to mind.

Now is the black stuff potassium carbonate because its white or are we loosing iron ?

FIIK. Seller hasn't said what it is. I was thinking either iron or nickel, both are in powder form I thought.

I thought that would be white, also thought it would be small quantities (invisible) in suspension, not in bulk.

Was your reside the same looking?

It's very fine when in suspension.

I've been promised a call this week, so I'll discuss the problem, cause, and solution at length.

dRdoS7