Author Topic: NiFe Cells (Read 12407 times)

Colaman · « **on:** August 26, 2006, 10:07:20 AM »

Hi All,

I'm in the process of putting together a system for my new place.

It will have about 1500-2000W of panels, a MPPT, two Outback power 2kW inverter chargers in parallel, a 3kVA generator and about 19kWh of NiFe cells.

This should be able to handle 3-5kWh/day of house load, depending on the season.

I would go for Gel or wet lead-acid cells except for one factor - sunlight. It's in the tropics at 16 deg S and has typical monsoon weather - clear winters , cloudy summers. A few seasons ago it was overcast over the wet season for 5 months straight. Needless to say, lead-acid systems take a bit of a pounding in those conditions and a lot of systems there had catastrophic failures. I get the feeling that whatever batteries I get, they might be used and abused somewhat :-) The system will probably be left ticking along by itself for a week or so at times.

I can source 400Ah cells relatively cheaply (AUD280/cell), from an Australian distributor of ChangHong Battery Ltd.

I'm looking at using 40 (2 strings of 20) to give a nominal 24V at 800Ah. I might drop that back to 19 cells a string to keep the peak voltage down a bit. The general gameplan is to run as much as possible off solar, with weekly charging back up to 100%. As such, I can deal with the low efficiencies of the cells, as I believe that in case the abuse tolerance makes up for it. I'll be getting a pentametric system monitor, picking up battery current, inverter usage/charging and panel current. As well as battery voltage, will probably pick up panel voltage before the MPPT. So it will be pretty comprehensively monitored.

Manufacturer is a little vague, but says charge at the C5 rate, float at 1.5V and boost at 1.73V per cell for no more than 8 hours.

So after that little essay, can anyone expand on this further? Any hints?

Cheers

Dave

Flux · « **Reply #1 on:** August 26, 2006, 04:53:40 AM »

Nife cells have not traditionally been used in float charge systems. You will most likely have to pick a float voltage a bit on the low side and be prepared to give them a good gassing occasionally.

There is a lot more variation in voltage than lead acid and inverters and other equipment intended for lead acid will likely object to the voltage range. They will either shut off due to over volts or under volts depending on the number of cells you choose for your string.

They are so tough that you may be able to resort to the end cell switch of the early lighting plant days and bring another cell or two in as they discharge. You may be able to swap the end cells occasionally to keep the loading more even.

You should be able to find data for NiFe/Brittania batteries but the chinese versions may have slightly different chemistry and may need volts tweaking a bit.

Keep the plates covered and change electrolyte regularly if you want long life.

Flux

ruddycrazy · « **Reply #2 on:** August 26, 2006, 06:54:10 AM »

I've got a bank of 10 nife cells and after heaps of research I found out the float voltage of a nife battery bank of 10 cells is 16.5 volts. So I madeup the oatley shunt regulator, changed a few resistors and made it to switch to the dumpload at 16 volts. I've found the nife bank perfect for powering my 12 volt cfl lights in the shed and as soon as I turn on 2 banks or 4 cfl lights the voltage drops to around 14 volts. I've had this system going for about 2 years now and even leaving the lights on all night still doesn't flatten the nife batteries. But as far as powering an inverter you'll need to workout how many cells will need to be in series to make the correct voltage for the inverter.

Cheers Bryan

rpcancun · « **Reply #3 on:** August 26, 2006, 08:40:59 AM »

So are NIFE cells better than lead acid?

Whats the cost diff?

wpowokal · « **Reply #4 on:** August 26, 2006, 08:58:02 AM »

One reason I have always declined these batteries is the cost of disposal, in Western Australia there are/were only two businesses able to receive them and it costs at the time of my enquiry A$6.5/kg for them to dispose of them.

allan down under

thunderhead · « **Reply #5 on:** August 26, 2006, 09:22:03 AM »

One reason I have always declined these batteries is the cost of disposal...

The cost of disposal may not be as high as you expect. They are almost non-toxic (a few people are allergic to nickel, and some electrolytes contain lithium, which is mildly toxic and, in large enough quantities, psychoactive) and anyway, in normal use you should be able to leave them to your grandchildren.

Some lucky grandchildren have received Edison's original pre-1920 NiFe cells from their grandparents, and are still using them.

DingBat · « **Reply #6 on:** August 26, 2006, 09:32:07 AM »

I thought NiFe batteries aka ironclads / Edison Batteries had a service lifespan of 40+ years, if you keep up with changing the electrolyte (KOH)?

Seems to me if the answer to the above is yes, then the disposal cost is insignificant when factored over the whole 40 years. How many banks of lead-acid batteries would you need to buy and dispose of over the same time period? I'm guessing 4 to 6 full replacements.

-- DingBat

Colaman · « **Reply #7 on:** August 26, 2006, 02:06:30 PM »

The high voltage swing is a bit of an issue, bit I should be able to keep it within the inverter specs alright if I use 19 cells.

For the high side 1.7 * 19 = 32.3V , the inverter is recommended operating up to 34V and will cutoff and log an alarm at 40V. On the discharge side, it can be programmed to cut at 18V and back in at 20, so it should fit within the discharge curve of the cells ok. The MPPT specs can easily handle the wider swings.

I don't think the bank will be actually sitting at float too often. It'll probably reach it once a day for a few hours in winter, but in summer all bets are off and it will likely only get there when I run the genset.

Colaman · « **Reply #8 on:** August 26, 2006, 02:30:27 PM »

Well, that's one of the factors I'm using when going with the Nickel-Iron cells.

I'll put in my thought processes here :

You buy a nickel-iron set - in my case for about $11,000. It takes a fair bit of fiddling to set up correctly , but after that, it's fine. It lasts 20 years overall, with, say, 5 cell replacements due to poor quality control at the factory and rough treatment. So it costs overall $12,000 or so.

You buy a fancy-pants set of Gel-Cells with the same effective capacity at 50% DoD ($22,000 for sungels here). You then use them at wildly varying discharge points, because it's cloudy half the year, and you can't be bothered going out and starting your genset 'cos it's out of fuel/needs an oil change/you're not there. After 5 years and a thousand accidental/necessary 100% DoD's, a few hopeful cell replacements with 'similarly aged' cells, they're out of usable capacity. So you dispose of that set ($$) and buy another set ($22,000). Repeat this for another two times to get to 20 years.

Nickel-Iron set = $12,000 over 20 years.

Lead-Acid set = $88,000 over 20 years.

The difference - $75,000 - buys a lot of fuel for the genset to make up for their inefficient nature. I did roughly do the calcs the other week for topping off with the genset - A 3kVA genset, bulk charge at 60A per string... gives, oh about 8-9 hours of running to pull them up from flat. Fuel consumption of the lister sets is about 3l/hr at 3kVA. 27 litres a run at $2/L (optimistic guesstimate in the future) gives $54 a week. Over 20 years, thats $50,000 in fuel.

But! I could go buy a nice 600W turbine for (guess) $5K and it would (guess) cut my genset runtime in half, making it $25,000 in fuel.

Or I could buy some more panels for $10K and it would do the same thing.

Or I could just learn to use the 'off' switch on a few things around the place. :-D

All of those can offset the lousy efficiency of the cells, and give me more power available as well. And they're certainly cost-effective, if you are prepared to work with their different characteristics.

There's a possibility also that the place might (oh , the horror!) be rented out. You need a bulletproof power system if that's going to happen, otherwise it's going to get real expensive, real quick.

Clifford · « **Reply #9 on:** August 27, 2006, 10:48:14 AM »

Wow,

It looks like you are trying to put together a BIG system.

There might be some advantages of finding some used Telco/UPS batteries... somewhere there have to be some that you can find that are cheap, with some life left in them.

I have seen a 14,000 pound, 120V (1400 AH for 120V, or 7000 AH for 24V) set of used Telco/UPS batteries in Kansas for Dirt Cheap. The problem would be getting you and the batteries together.... And, of course, used batteries are often sold without warranty. So, if you spend a couple of grand on shipping only to have the batteries not hold up, it would be a problem.

Maybe you can find some ones locally.

whatsnext · « **Reply #10 on:** August 27, 2006, 12:54:47 PM »

Clifford, How are those lead calciums working out for you. I'm curious as to how they react to a load onced charged.

John.........

Caradoc · « **Reply #11 on:** August 27, 2006, 09:15:23 PM »

Colaman: Go with 19 cells. Here's extract from email I'm in the middle of writing at the moment...

**text follows*

Well, you can (and maybe ought?) to use fewer NiFes than simple math would

indicate, but more because they have enough internal resistance that they like to

be overcharged rather than because they can be run down flat without damage. My

buddy with the Eagle Picher cells can't decide whether he's happier running 37 or

38 cells in his single series 48-volt battery. (At 1.2 volts per cell, you'd think

that 48 divided by 1.2 would be 40 cells.) Similarly, a guy I know with an antique

32-volt Wincharger system has always used 25 cells in a series. (Again, 32 divided

by 1.2 would be 26.66 cells.) Based on those two examples, I'd guess that a

24-volt system would go with 19 cells rather than the 20 indicated by the math.

Despite the above, I bought 40 cells for my 48-volt system so as to have a couple

of spares. Fortunately, today's inverters are smart enough to read 19 x 1.2 = 22.8

volts as 24 volts that has run down a bit and adjust to give you clean 117 or 120

volt alternating current on the other end. Don't know about Outback (should be as

good or better), but my Trace SW5548 inverters (or their charge controllers I

should say) have a higher output setting for charging NiCad and Nife. One big

advantage of NiFe is the ability to create one series of single cells rather than

two or three series of multicell batteries in each string. Not only is wiring/

charging/ discharging simplified, but with lead-acid all it takes is one lazy cell

in one battery of one string to reduce overall system performance.

*end of text*

Whatever brand you choose, do be aware that the various advantages of NiFe derive

from the fact that the chemical reactions (both charge and discharge) end up being

in the electrolyte rather than the plates. Long life? Yeah, almost indestructible.

But the underlying chemistry says that they bubble out hydrogen and oxygen on both

charge and discharge. Two consequences: (1) for safety, wou will want good

ventilation and (2) since you'll need to monitor water level and add distilled

water on a regular basis to keep the plates covered, your cell bank will need to be only one cell deep. (You might want to think about saving/using that hydrogen somehow and I for one will be tinkering with plumbing up an automatic watering system.)

ChangHong's WI-TN400 cell (actually 420 Ah)is 5.5 inches wide (138 mm). Rather than doing two strings of cells in parallel, I'd suggest asking whether distributor can supply the WI-TN800 cells (actually 820 Ah) which are 7.4 inches wide (185 mm). Either way, the series connectors will purposely add about 7/8" between the cells.

I went with a different manufacturer for about the same price, partly because their spec sheet shows less internal resistance than either ChangHong or Shenzhen and -- I'll admit it -- partly because I prefer the looks of their cells over the other two whether in transparent or translucent cases. I'll ask whether they have an Australian distributor and post the answer later.

Final thought: you want a thin layer of oil on top of the electrolyte. It's not to minimize frothing as some believe but to prevent atmospheric carbon dioxide from combining with the electrolyte and gradually reducing capacity. I'll close with extract from Home Power magazine back in 2004 or so...

*text follows*

from http://home.cybertron.com/~edurand/Otherst...uff/Edison.html

Cell Oil Layer

Check the thickness of the mineral oil layer floating on top of the

electrolyte. This oil layer is there to prevent carbon dioxide in

the air from reacting with the potassium hydroxide electrolyte.

For technical data about this phenomena, see George Patterson's article

in this issue. From a user's maintenance standpoint, there should

be a layer of mineral oil between 1/8 and 3/16 of an inch thick floating

on the surface of the electrolyte. If you need to add more oil then

use Chevron "Utility Oil 22". Don't use motor oil, mineral oil from

the drugstore, cooking oil, or anything else. If you fail to maintain

the oil layer, then the cell's electrolyte will gradually become

polluted with carbonates and will require replacement. If the oil

layer foams when a fully charged cell is under charge, then this

is a good indicator that the oil layer is too thin. So add more

oil to foaming cells.

*end of text**

Caradoc

Caradoc · « **Reply #12 on:** August 27, 2006, 10:19:01 PM »

I see I said something possibly misleading in previous post. Also, you're apparently allowed only one image per post (and they should be reduced in size since this forum apparently expands the image!)

So.... My comment about the chemical rection "ending up" as something going on in the electrolyte rather than the plates was meant to explain the fizzing on both charge and discharge, not to indicate that the plates aren't involved. Actually, depending on which direction the electrons are going, you've almost always got oxygen going back and forth between the plates either converting iron (II) oxide back to simple iron on the negative plate so it can oxidize nickel (II) oxide to nickel (III) oxide on the negative plate or doing the exact opposite. This plate-oriented view of the chemistry helps explain the durability of NiFe cells. Although ferric oxide (iron [II] oxide) is black rather than the familiar red of ferrous oxide, here's something downright elegant about the thought of an iron plate getting a molecule-thick film of rust and then switching back to being totally unrusted. Not much to go wrong there as the years go by.

Below is snapshot of the NiFe cells that I think are prettier than the competition.

Caradoc

PS: My wife thinks I should have gone with transparent case rather than translucent.

Caradoc · « **Reply #13 on:** August 27, 2006, 10:22:15 PM »

Maybe you're only allowed one image upload per day? I'll give it one more try before I give up. -Caradoc

Colaman · « **Reply #14 on:** August 29, 2006, 01:26:36 AM »

Thanks for the info Caradoc. I'll have to take your word on the cell process - it all looks plausible, but electrochemistry was a long time ago for me now :-)

I'll probably look into a watering system for it after it's setup and I can get a handle on how much topping up is required. I wonder how recombinant cell caps would go.... I stumbled across a research paper about recombinant catalysts with NiFe cells that gave good results. But saying that I've heard of a few cases of melted caps on lead-acid systems that are gassed a fair bit - presumably from the heat from the catalyst - so the extra H2/O2 from NiFe cells would probably overload a standard cap designed for lead-acid cells.

And on that note, I have to wonder if a simple rubber flap on top of each vent would help keep the CO2 out as opposed to mineral oil - all that gassing going on would surely displace any atmospheric gases inside the cell pretty quick.

I was thinking of 40 smaller cells as opposed to 20 larger ones as I'm still tossing up between 24/48V. The area around where the battery bank is quite open, so there's room to simply go around and water the other side without much hassle. But I might drop the distributor a line and see if he can get a hold of the 800Ah cells, as the proportionally larger voltage swing at 48V might exceed my inverter specs a little.

I'd be keen to see if any other NiFe cell manufacturers have dealers in Australia - not too many choices here it seems.

And I have to say, this is the first place I've asked q's about nickel iron cells where no-one has looked at me with raised eyebrows, like I'm some sort of sicko freak!

I might have to drop by more often. :-D

Nil · « **Reply #15 on:** August 29, 2006, 09:06:16 AM »

I'm not sure if you searched it up but I had a post going a while back about NiCd cells. It has a couple links that may help you, or others out.

http://www.fieldlines.com/story/2006/1/25/51823/1799

coldspot · « **Reply #16 on:** August 30, 2006, 08:20:56 AM »

WOW-

While trying to research

"McGraw Edison N.P. 93-15"

Edison battery cells I got last weekend

12, (looks like two in each to make one)

I found this post here where I usually hang out, LOL

And somebody even tried to point me here but I thought they ment

a SLA post I saw and was also learning from. LOL

What can I use to clean up these cells???

They are pretty bad, and smell also!

What can I use to replace

electrolyte with? Or should I just only add Distilled water

and try to find some "Utility Oil 22"??

Mainly for right now what I need to do is clean them up

and build a storage case for them.

So any advise on the clean up??

Right now they are all loaded up in my truck,

Lucky I researched a bit longer, I was headed to car wash hours ago.

Man I love this forum,

It made me a R.E. Fan!!!

coldspot · « **Reply #17 on:** August 30, 2006, 08:29:15 AM »

oop's-

forgot,

I saw this one,

Flux-

"Keep the plates covered and change electrolyte regularly if you want long life.

Flux"

Could you go into that a bit more maybe?

??

please!

Thanks

Colaman · « **Reply #18 on:** August 30, 2006, 11:49:44 AM »

From what I've read, 30% potassium hydroxide (KOH) solution is about right for these cells. Some mention a small quantity of lithium in the mix, but no specifics are given ... so straight KOH should do the job ok.

A quick google search reveals many chemical supply companies that can provide it pre-made.

You could make it yourself with the dry ingredients and distilled water if you're keen - it'd probably work out cheaper. You want 30% by weight, so that's 30 grams of dry KOH plus 70 grams of water - scale accordingly to the volume you need for your cells. It probably doesn't matter that much if you're a few percent either way from 30%, so don't get too paranoid about the weights.

Chemistry suggests that you should add small quantities of the dry KOH to the water at a time, as a fair bit of heat will likely be given off - don't do it the other way around and add the water to the KOH, you'll probably get a bit of a steam explosion - or at the least much percolating.

The KOH solution absorbs carbon dioxide from the air over time making a carbonate, which doesn't get used in the cell chemistry and so battery efficiency is reduced. That's what the oil is for - to act as a barrier to keep the air away from the solution. As for cleaning them, if they're covered with fur / crud, an acidic mix (eg vinegar) will neutralise it and you can scrub it off. Try not to get anything in the cells though.

I'll also post a link here to a model nickel-iron cell, just for posterity. Woeful capacity, but all the theory is there for an enterprising person to make one themselves based on it. And - suprise! - a google search comes back home to roost here with a discussion on NiFe electrolyte.

Ah, google. Where would we be without it?

coldspot · « **Reply #19 on:** August 30, 2006, 12:15:21 PM »

Colaman-

Thanks!!!!

I've read all info here

I'm thinking to just clean them up and add D-H2O

and check the oil also. lol

LOL,fur would be mild.

Totaly nasty stuff here.

Thanks also about the vinegar

What about the old baking soda?

I quess thats for lead "Acid", lol

Colaman · « **Reply #20 on:** September 01, 2006, 01:18:10 AM »

I've pushed my power calculation spreadsheet online. I use it when I'm just fiddling with the numbers to see if things are plausible. It's at :

http://users.on.net/~dgriffith/powercalcs.xls

(for the excel 97 and up version)

or

http://users.on.net/~dgriffith/powercalcs.ods

(for the OpenOffice version)

Basically:

Three sheets - Panels, Batteries and Loads

Panels -

You can enter the number and configuration of the panels (eg 16 130W panels, in 4 strings of 4). Give the spreadsheet the OCV, max power voltage and current and it will figure out the array OCV, max power voltage and max current. It'll give you the array price as well. Stick the sun-hours in for each month into the table and it will give an indication of output and a min/max/average for the year.

Batteries -

Same sort of thing as the panels sheet, define your battery bank, number of cells and string configuration. It will give you the pack voltage and Ah. Give it the DoD and it will calculate the available power of the pack in kWh. Give it the charging efficiency and it will work out how long it will take to charge the pack from the data given on the panels page. Once you fill out the loads page, it will calculate the time needed to charge with the house load connected (with avg/max/min sun hours from the panels page), and days from full charge to flat with the house load with no sun. The charging amps and % of Ah capacity are calculated assuming a MPPT is used and with no consideration of it's efficiency, but you can fudge that into the charging efficiency if you want. If you're battery/array voltage is the same, no consideration is given to array/battery mismatch and subsequent power loss if you're not using a MPPT.

Loads-

Fill out the power consumption of each appliance and the time used per day and it will sum up the power used for the day in watts, and calculate the surplus from the panels, again with avg/max/min sun hours.

Let me know what you think.

Caradoc · « **Reply #21 on:** September 07, 2006, 04:45:14 AM »

Dave:

Good news is that my source in China makes 800 Ah cells (or up to slightly over 1,000 Ah for that matter) and whether at 400 or 800 would be a bit cheaper than their competition even after shipping to Australia and allowing for Australia's 5% import duty and the compounded 10% tax on top of FOB price plus duty.

Bad news is that, as a domestic manufacturer for the Chinese market, they do not have an Australian distributor so you'd have to have them imported yourself just as I had mine imported into the US. The experience wasn't too painful, but for my next batch I'm going to try to pre-pay the 3.6% US import duty rather than get stuck paying $55 for a few days worth of $5000 customs bond. (Seems like a waste of money to pay for 5 grand worth of bond for the purpose of assuring bureaucrats that they'll definitely get their 3 or 4 hundred in import duty even if my trucker never show up to get the hardware out of the bonded warehouse!!)

If you'd like a current quote sent to you (priced in Australian dollars per Ah) for FOB Australian port of your choice, shoot me an email at g_owen_home@yahoo.com and I'll have them respond directly to you.

If you have no desire to get involved in the import business (either for your own use or for selling to the Australian market in the future), the following will be of no interest....

Source for 5% import duty: Go to http://www.apectariff.org/tdb.cgi/ff3133323230/apeccgi.cgi?AU , click "search" at top and do search for nickel-iron. That will lead you to 5% duty on "Harmonized System" code of 8507.40. Or, at same site, just drop down to Harmonized System Code and type in 8507.40

Source for indication that Australia charges 10% tax on top of FOB plus duty:

http://www.ita.doc.gov/td/tic/tariff/country_tariff_info.htm#Australia

Two final thoughts... (1) In comparing to competition's price for batteries already in Australia and assuming practices in Australia are similar to here in US, savings will actually be less than the math indicates because of piddly things that nobody tells you about ahead of time like warehouse charging a $10 fuel surcharge and -- believe it or not -- the port authority charging $6.10 for allowing truck onto the pier. So, allow an extra $100 or so for things like that. (2) If filling out customs paperwork isn't your cup of tea, it might be worth $90 to have a worldwide logistics company take care of the details for you. Some good ones are W M Logistics, Probus One Touch, and AIT Worldwide.

Caradoc

Colaman · « **Reply #22 on:** September 08, 2006, 03:16:11 PM »

Thanks Caradoc, I'll shoot you an email and we'll see how things go.

Haven't asked the supplier here about higher Ah cells yet - I really must get around to it.

I've got about 18 months or so before all the bits for the system have to be here so there's no great rush ... yet. :-)

Caradoc · « **Reply #23 on:** December 06, 2007, 10:29:21 PM »

Colaman:

Hope you got more accomplished over the last year than I did! Did your system come together?

Caradoc

shay · « **Reply #24 on:** May 11, 2009, 10:59:10 PM »

Just received 40 and will be testing them for a 661 amp discharge over 100 hours (.01C). The cells are rated by the manufacturer as nominal 500 Ah. Is this 100 hour discharge rate reasonable or is the importer misrepresenting/overcharging for these cells? The cells weigh 42 pounds dry and I expected them to weigh 49 pounds from the importers literature. He claims I should be happy that I saved the cost of shipping and I say I'd rather pay the shipping ($330 for 2500 lbs) when they initially cost $10 a pound.

shay · « **Reply #25 on:** May 12, 2009, 08:42:36 PM »

Advice: The dry weight and volume of a NiFe cell are diagnostic. The technology is about a century old so modern weights/volumes don't shimmy and shake like the girls downtown. It is not difficult to switch your purchase to the next smaller cell by using a deceptive 100 hour rating thereby decreasing the value of your purchase by 25%.

News: