Nickel-Iron woes.

Hi,
I have 40 x 200Ah NiFe cells, which I bought & installed in 2016.
Early last year I started having cells fail to hold charge. I happened to be up early, and saw the voltmeter on one group of 10 cells was lower than the other 3.
I tested each cell's voltage, also noticed that some had a layer of black debris in the bottom, in one it was up to the plates.
The voltages in them would drop to 0.6V, then -0.2V as the bank was discharging.
Also they were really bubbling, even though no charging was occurring. Charge going from the good cells into the bad?
Actually, checking back through my log of daily charge/discharge Ah readings, I found mention of a few that had problems, but that was short term, and they were OK once I'd had them for a while. They've been really good since mid 2017, and even better after I upgraded the inverter, and added 4KW of solar to the existing 3KW in 2018.
The seller sent me a bag of KOH, which I used to replace the electrolyte. I gave 6 of the cells a good flush, and got them totally clean before replacement.
After putting them back, and several charge/discharge cycles, I started testing. Then another went -0.2.
So now I've had 7 now go "bad".
I then really overcharged the 7 of them (1.9V / cell). More testing , 4 didn't recover, 3 possibly did. The last bad one I didn't clean out or renew.
Here's some pics:

This the worst of the cells.

This the crud in the bottom. Don't ask why there's no plates!
I will add that I have only 39 now.
These are the last lot of readings:

Anyway, the reason for the post is to ask if any other NiFe owners have seen this.
Be interested to know, there seem to be a few owners here, and some have had experience with them for a long time.
The seller is going to replace 4 cells, as soon as he has some.
My concern is what will happen in the future. Of the 40, only 3 have no crud in them.
I am assuming the crud is from the anodes and/or cathodes disintegrating.
I've been Googling, but found no mention of my experience.
Many thanks,
dRdoS7
PS. I have posted this in a few other forums, trying to get as much info from others as possible.
I have 40 x 200Ah NiFe cells, which I bought & installed in 2016.
Early last year I started having cells fail to hold charge. I happened to be up early, and saw the voltmeter on one group of 10 cells was lower than the other 3.
I tested each cell's voltage, also noticed that some had a layer of black debris in the bottom, in one it was up to the plates.
The voltages in them would drop to 0.6V, then -0.2V as the bank was discharging.
Also they were really bubbling, even though no charging was occurring. Charge going from the good cells into the bad?
Actually, checking back through my log of daily charge/discharge Ah readings, I found mention of a few that had problems, but that was short term, and they were OK once I'd had them for a while. They've been really good since mid 2017, and even better after I upgraded the inverter, and added 4KW of solar to the existing 3KW in 2018.
The seller sent me a bag of KOH, which I used to replace the electrolyte. I gave 6 of the cells a good flush, and got them totally clean before replacement.
After putting them back, and several charge/discharge cycles, I started testing. Then another went -0.2.
So now I've had 7 now go "bad".
I then really overcharged the 7 of them (1.9V / cell). More testing , 4 didn't recover, 3 possibly did. The last bad one I didn't clean out or renew.
Here's some pics:
This the worst of the cells.
This the crud in the bottom. Don't ask why there's no plates!
I will add that I have only 39 now.

These are the last lot of readings:
Anyway, the reason for the post is to ask if any other NiFe owners have seen this.
Be interested to know, there seem to be a few owners here, and some have had experience with them for a long time.
The seller is going to replace 4 cells, as soon as he has some.
My concern is what will happen in the future. Of the 40, only 3 have no crud in them.
I am assuming the crud is from the anodes and/or cathodes disintegrating.
I've been Googling, but found no mention of my experience.
Many thanks,
dRdoS7
PS. I have posted this in a few other forums, trying to get as much info from others as possible.
Comments
Never a silly question.
You might consider sending in both a sample of the battery sludge and your home distilled water to a lab for analysis. Between those two you should be able to tell if the problem is on yours or the battery mfg side of things.
What make are the batteries?
There is a member here Mike who can give you his opinion as a user.
http://members.sti.net/offgridsolar/
E-mail [email protected]
Initial install pics (Oct 2011)
https://www.facebook.com/pg/Lucky-Monkeys-Ranch-120212794718849/photos/?tab=album&album_id=209715335768594
https://www.facebook.com/pg/Lucky-Monkeys-Ranch-120212794718849/photos/?tab=album&album_id=2113125788760863
|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
|| VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A
solar: http://tinyurl.com/LMR-Solar
gen: http://tinyurl.com/LMR-Lister ,
I started with 3KW, then after 2 years I installed another 4.3KW. I have plans of putting in another ~3KW soon. I find in winter, sometimes what I have isn't enough. But then what is? I could say the same about battery capacity too.
Tell me if you can see this one:
I just signed out, then had a look, and I can see all the photos, maybe it's a browser problem?
I can't recall an active poster with NiFe cells. Transparent housing is interesting. You are on the grid maximizing "solar exports" yet use batteries for energy storage. Mark K might have a chance at diagnosing these NiFe woes.
Strange. Whether I'm logged in or not, I can only see photos, no links.
That's even stranger. I can see the photos here, logged in or not, but not the ones on SPT unless I log in there.
I've weighed a few of the cells to see what the difference is between those with no debris, those with debris, and those that have been flushed and renewed.
According to the specs., a 200Ah cell should weigh 14kg.
I'm wondering if anybody who bought new cells has weighed them. If so, were they up to spec?
I contacted the seller a "few" weeks ago, and the cells he ordered have arrived in port. Said it would probably take another week (or two) before he has them. Then another week before he has charged/discharged a few times, and will send them to me.
Of the 6 cells I flushed, and renewed, only 2 are working. The other 4 still acting the same as before, and I've removed them from the bank.
Currently running 35 cells.
Thanks,
dRdoS7
I would be (a little) surprised that the cells would lose weight over time...
-Bill
Me neither!
Been a while. The 6 cells I was expecting didn't arrive. I contacted the seller in June. He told me they weren't holding a charge, and didn't want send them. He said he had more coming, and would send 10. No contact for a few months. Called him last week and told him I wanted to return the cells, and get a full refund. Left it at that, called again Monday, and he agreed. He is going to refund 50% this week, and the other 50% when I return the cells, at his expense. So my NiFe adventure is over (hopefully). Sadly, it didn't work out as planned. They worked wonderfully for about 2 years.
I've ordered 18 x 280Ah LFP.
Thanks,
dRdoS7
|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
|| VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A
solar: http://tinyurl.com/LMR-Solar
gen: http://tinyurl.com/LMR-Lister ,
http://members.sti.net/offgridsolar/
E-mail [email protected]
Yes, it was good while they lasted. Made a big difference to my solar credits from the grid connected system. That really dropped the first 2 quarters this year. Still, I don't have to make any more distilled water. Also, my wife is pleased: she was worried about what to with the batteries if I died.
Should you be considering a DIY bank I'll gladly share my contact if it is not in violation of forum policy, I refer this to @BB. If there is any objection, being that you're in Australia I suspect not, but you never know.
Second system 1890W 3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.