Nickel Iron vs. Lead Acid - Off Grid battery debate

[Iron Bran]

More ni-fe research

Some old gov't reports on ni-fe batteries. Interesting ideas for cycle life test.

[Iron Bran]

Lithium Hydroxide now available -- Electrolyte Refresh

Hi everyone,

I just recieved 2kg of LiOH for mixing with the KOH in the Ni-Fe electrolyte.

(This may be one of the only places in the world where that actually makes sense)

If you are looking for some LiOH for an electrolyte refresh, or even for improving efficiency of your hydrogen generator, do let me know.

brandon@ironedison.com

[Mike90250]

I like the inverter, not a speck of trouble from it, starts the well pump, runs the welder, and keeps the fridge cold. the current old batteries are the weak spot.

[Iron Bran]

Xantrex XW info

Here is the manual for the Xantrex XW 6048... How do you like using this inverter?
I really like all the settings for the time-of-day grid-tie buy/sell operation. Some of my customers (and I) are very interested in the 4024.

Cool ! Thx for the shot (and manual) I'll have to see what the XW6048 max input is, and if my Morningstar MPPT can go that high.

Alkaline Batteries
48V bank:
Bulk = 67.2V
Float = 62V

Hmmm... XW6048 range is 44-64 VDC So I'll call a stop at 63V Can't fry a $3.5K inverter.

Hmmm Hmmmm. MS TS MPPT 60
custom settings - page 19, limits ?? there is a preset that will take me to 62VDC, and I think the battery limit is 72V My array is about 90V (5, "12V" panels in series )

[Mike90250]

Cool ! Thx for the shot (and manual) I'll have to see what the XW6048 max input is, and if my Morningstar MPPT can go that high.

Alkaline Batteries
48V bank:
Bulk = 67.2V
Float = 62V

Hmmm... XW6048 range is 44-64 VDC So I'll call a stop at 63V Can't fry a $3.5K inverter.

Hmmm Hmmmm. MS TS MPPT 60
custom settings - page 19, limits ?? there is a preset that will take me to 62VDC, and I think the battery limit is 72V My array is about 90V (5, "12V" panels in series )

[Iron Bran]

Charge settings for winter, Ni-Fe specific charger

Very interesting, there are no charge controllers that I know of that can re-adjust based on date, but this is a functionality that could easily be built in.

The kind folks over at Apollo offered to update the firmware to say Ni-Fe when I spoke to them about charge settings. I bet they would be interested in hearing this "SEASONAL" setting, although now that I think about it, this problem is solved by using a temp sensor.

Please check out the Xantrex Classic series charge controllers / diversion controllers (great for all you micro-hydro or wind powered folks) Note - this is a PWM charge controller

Ni-Fe charge settings for C-Series:




Full instruction manual - attached

[isoutar]

Lot temperature perfomance of NiFe cells

Thanks for the Changhong data. That is for a normal mix of electrolyte. The guys in northern Canada are using a special concentration of KOH with no LiOH added. The curve for their batteries is optimal around zero degrees C. The guy doing the low temperature research says that at -40C his cells are only at 60% capacity.

Do you know what electroyte mix was used for the low temperature performance curve set?

Thanks for the data

Ian Soutar

1) low temp performance
Changhong_DeRating chart indicates this. (attached)

2) I have a 700ah 48V bank (40 cells) on order, and wondering what, from your experience has been, are good charge controller set points for winter & summer. I've got the Morningstar MPPT 60, which has a completely user settable field.

[Mike90250]

1) low temp performance
Changhong_DeRating chart indicates this. (attached)

2) I have a 700ah 48V bank (40 cells) on order, and wondering what, from your experience has been, are good charge controller set points for winter & summer. I've got the Morningstar MPPT 60, which has a completely user settable field.

[isoutar]

Please email me ... I can date those NiFe cells

If you email me I can put you in contact with a dating expert for old Nickel Iron cells for the 1920s. Many of them are still in use after some rejuvenation (washing and refilling with electrolyte.) People are curious about their ancient cells and this question of dating keeps coming up.

I will try to track down the dating codes to post here as well.

Ian Soutar

[isoutar]

Multiple charge voltages for nickel iron depending on conditions.

This is an interesting possibility ... multiple charge voltages for NiFe depending on season.

In the winter I charge to a full charge. That is because the sun might only be out for 2 hours and I want to pack the most energy into it.

In the spring and fall I change to midway between a full charge and a float charge.
In the summer I switch to just a float charge. These changes are done to prevent the need to water the batteries as often.

The controller is programmed with the new values at each season change. Since I design electronic products for a living, our company is designing an ideal nickel iron battery charger that takes advantage of the seasonal charge voltages.

I have never seen another battery design where you can simply choose the charge voltage that is most convenient. They cannot be destroyed even if you make a drastic error in this voltage.

Hey,

I am very interested on your thoughts on different efficiencies at different charge levels.

Here is a detailed writeup I found on charging, and I would like to hear what you think. Especially the 2nd paragraph. Granted, this is for NiCd but I just want to point out that efficiency is not exactly constant. Anyways amigo, check this out...

To obtain a sufficient voltage drop, the charge rate must be 0.5C and higher. Lower than 0.5C charge rates produce a very shallow voltage decrease that is often difficult to measure, especially if the cells are slightly mismatched. In a battery pack that has mismatched cells, each cell reaches the full charge at a different time and the curve gets distorted. Failing to achieve a sufficient negative slope allows the fast-charge to continue, causing excessive heat buildup due to overcharge. Chargers using the NDV must include other charge-termination methods to provide safe charging under all conditions. Most chargers also observe the battery temperature.

The charge efficiency factor of a standard NiCd is better on fast charge than slow charge. At a 1C charge rate, the typical charge efficiency is 1.1 or 91 percent. On an overnight slow charge (0.1C), the efficiency drops to 1.4 or 71 percent.

At a rate of 1C, the charge time of a NiCd is slightly longer than 60 minutes (66 minutes at an assumed charge efficiency of 1.1). The charge time on a battery that is partially discharged or cannot hold full capacity due to memory or other degradation is shorter accordingly. At a 0.1C charge rate, the charge time of an empty NiCd is about 14 hours, which relates to the charge efficiency of 1.4.

During the first 70 percent of the charge cycle, the charge efficiency of a NiCd battery is close to 100 percent. Almost all of the energy is absorbed and the battery remains cool. Currents of several times the C-rating can be applied to a NiCd battery designed for fast charging without causing heat build-up. Ultra-fast chargers use this unique phenomenon and charge a battery to the 70 percent charge level within a few minutes. The charge continues at a lower rate until the battery is fully charged.

Once the 70 percent charge threshold is passed, the battery gradually loses ability to accept charge. The cells start to generate gases, the pressure rises and the temperature increases. The charge acceptance drops further as the battery reaches 80 and 90 percent SoC. Once full charge is reached, the battery goes into overcharge. In an attempt to gain a few extra capacity points, some chargers allow a measured amount of overcharge

[isoutar]

Lots of Experimentation with Nickel Iron Cells underway in Canada.

Iron Bran

Thanks for your discussions ... lots of real experience in the forum here with Nickel Iron cells now. A year ago it was mostly theoretical talk.

In Canada there are a number of large experiments underway this year using Nickel Iron cells. The largest installation will be in Manitoba where a 3000 ah system at 48 volts is going in. There is another system I know of in Northern Manitoba ... one that needs to operate at negative 40 degrees C in the winter. The owner is installing them outside and under his cottage specifically to see how well they work at -40 C or lower.

He had previously used lead acid banks but several were destroyed when his charge controller failed mid winter, the cells discharged, froze and were ruined.

I am not sure where the rumour came out that NiFe cells do not work in cold temperatures. It is one of their strong points.

A noteable old installation ... the main Toronto library has a bank of NiFe that they are still using to back up some of their computers. The power backup system was installed in the late 1960s and is still in use.

Canada is only just beginning to use NiFe cells again in large government funded projects and in some smaller privately owned energy systems.

Ian

Hi everyone,

I am interested in learning if you have any experience with non-traditional battery systems?

Is anyone using ni-cad or nickel iron? I am looking into Nickel Iron (ni-fe), anyone currently using these?

Thanks!

[Iron Bran]

How did you identify the year??

Hi,

I have some old ni-fe batteries and need to find what year they are from.

Model: A6H
Serials:
2113AD
2146AD
2145AD
2156AD

I have a small solar system that powers my garage. The solar panels add up to 90 watts. This has been in use now for ~ 5 years to power the lights, televison, radio and small power tools. The batteries I have been using are whatever is lying around, primarily glassmat alarm batteries and Nicads. I was about to buy a set of golf cart deep cycle lead acid batteries then remembered I had a bunch of Edison Nickel Iron cells on a shelf hidden by years of accumulation. I bought these in the late 70's from different sources and never used them. The electrolyte had long dried out to the point is was not visible through the fill caps. The newest set was manufactured in 1961, the oldest before 1928. After much research, I figured out the formula for the electrolyte and replaced it. This was followed by cycle testing with a motor/generator set and load resistors. In the end, the set made before 1928 is still at 65% of new rated capacity. The set made in 1961 is at 70-75% of new capacity. I have been using the newer set for a year now and am thrilled with the performance. I know they are expensive but seem to be a good fit for solar systems. Unlike other batteries, they really are nearly indestructible. I don't even have a charge controller hooked to them. I will get one at some point but just add water ever 3-4 months for now. The only difference to be considered with these is the need for a different charge controller. The fully charged voltage of a nickel iron set produces 14-15 volts and will trip off inverters designed for lead acid. There are inverters available with adjustable set points. For now, when working in the garage, I momentarily remove a couple of cells from the circuit to get the inverter started, then apply a load. Works for now !

[isoutar]

Operating NiFe without a charge controller at all.

I initially ran my bank of NiFe cells without a charge controller just to verify that this kind of abuse will not affect the cells. I needed to add water after a week since the batteries were charged by 10 or 11 in the morning and just bubbled hydrogen for the rest of the day. No problems though ... overcharging has no negative effect at all on Nickel Iron Battery systems ... you just have to keep on top of the water.

But when I switched to an Outback MX60 controller and set the charge voltages, then I only needed to fill the batteries a bit in spring and fall.

I would recommend a charge controller but it is not essential with Nickel Iron as long as you are willing to fill the batteries regularly.

Ian Soutar

I have a small solar system that powers my garage. The solar panels add up to 90 watts. This has been in use now for ~ 5 years to power the lights, televison, radio and small power tools. The batteries I have been using are whatever is lying around, primarily glassmat alarm batteries and Nicads. I was about to buy a set of golf cart deep cycle lead acid batteries then remembered I had a bunch of Edison Nickel Iron cells on a shelf hidden by years of accumulation. I bought these in the late 70's from different sources and never used them. The electrolyte had long dried out to the point is was not visible through the fill caps. The newest set was manufactured in 1961, the oldest before 1928. After much research, I figured out the formula for the electrolyte and replaced it. This was followed by cycle testing with a motor/generator set and load resistors. In the end, the set made before 1928 is still at 65% of new rated capacity. The set made in 1961 is at 70-75% of new capacity. I have been using the newer set for a year now and am thrilled with the performance. I know they are expensive but seem to be a good fit for solar systems. Unlike other batteries, they really are nearly indestructible. I don't even have a charge controller hooked to them. I will get one at some point but just add water ever 3-4 months for now. The only difference to be considered with these is the need for a different charge controller. The fully charged voltage of a nickel iron set produces 14-15 volts and will trip off inverters designed for lead acid. There are inverters available with adjustable set points. For now, when working in the garage, I momentarily remove a couple of cells from the circuit to get the inverter started, then apply a load. Works for now !

[Iron Bran]

Charge / Discharge Chart

Real data...

[isoutar]

Yes ... there are people using NiFe cells for RE and are pleased with them.

Yes, my wife and I are living with Solar and Nickel Iron cells for all our lighting and computers.

Very pleased with them ... I have abused them like crazy ... discharging them completely for several weeks around christmas time last year. Their performance improved remarkably just as Edison had suggested. I think you can kill them ... but it might take a sledge hammer to do it.

I was going to sell them but I got into a geiger counter project and I decided I was not into being a battery salesman. In addition a service club is hiring my company to do a bunch of solar powered lighting systems for African schools and hospitals. These will all be NiFe systems. The service club had built solar schools over the last decade but each school ended up having a large graveyard of lead acid batteries ... they were thinking of abandoning the solar approach because of the lead batteries! A woman from Africa I met last week was speaking of the mess that lead batteries have created in her small town.

I also recommended nickel metal hydride for smaller installations in the home where the flooded stationary nife battery system was inappropriate. Nickel Metal Hydride is worth looking at ... the D size cells put out 10 amps at 1.2 volts. Another friend runs his car (gasoline car) with a battery pack he made up using D cells. The battery pack is about 1/3 the size of the original lead acid battery he was using. This kind of pack is great for small huts and cabins to provide for LED lighting.

Nickel Iron cells sure are worry free ... it is great to be able to overcharge them for weeks too. Last summer I ran them at the peak of summer just connected to my solar panels ... a drastic overcharge. I kept adding water each week because the overcharge uses water. But again their performance improved slightly ... but not as much as they improved after a few deep discharges.

I would not recommend running with no charge controller unless you like buying distilled water!

Ian Soutar

http://www.microsec.net

UPDATE: Working on bringing some very old Edison cells back to life. One cell is holding a charge, and I just opened up three of the perforated metal cases.

https://picasaweb.google.com/110321674492695329085/InsideTheNiFeCell

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