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Nickel iron batteries, a long term prep ?
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sam_uk



Joined: 20 Oct 2008
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PostPosted: Tue Feb 14, 2012 12:34 am    Post subject: Reply with quote

I recently found out about Nickel Iron batteries.

40+ year life in a solar scenario. Reports of some cells still functioning after 100 years.

Not damaged by deep discharge, and no toxic chemicals. Still at research phase for me, but sound interesting.

More here
http://www.nickel-iron-battery.com/

About 4000 for 500Ah/12v (@US Prices) http://www.zappworks.com/battery_prices.htm
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mikepepler
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PostPosted: Tue Feb 14, 2012 8:54 am    Post subject: Reply with quote

sam_uk wrote:
I recently found out about Nickel Iron batteries.

40+ year life in a solar scenario. Reports of some cells still functioning after 100 years.

Not damaged by deep discharge, and no toxic chemicals. Still at research phase for me, but sound interesting.
Interesting, but some info on the wikipedia pages shows some down downsides:

"Due to its low specific energy, poor charge retention, and its high cost of manufacture, other types of rechargeable batteries have displaced the nickeliron battery in most applications."

"While the slow formation of iron crystals preserves the electrodes, it also limits the high rate performance: these cells charge slowly, and are only able to discharge slowly."

"Nickeliron cells should not be charged from a constant voltage supply since they can be damaged by thermal runaway; the cell internal voltage drops as gassing begins, raising temperature, which increases current drawn and so further increases gassing and temperature."

Looks like they've been made for over 100 years, and more research is now being done, but for now I think lead-acid still wins...

http://en.wikipedia.org/wiki/Nickel%E2%80%93iron_battery
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adam2
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PostPosted: Tue Feb 14, 2012 9:31 am    Post subject: Reply with quote

Nickel iron batteries are worthy of consideration by hard core doomers in view of the very long life, at least 30 years and up to 100 years.
They do however have a number of drawbacks, and are not a drop in replacement for the far more common lead acid battery.

Each cell is only about 1.2 volts, therefore more cells are needed for a given voltage.
The voltage variation is much greater than with lead acid cells. A 10 cell (12 volt nominal) nickel iron battery will take as much as 17 or even 18volts to fully charge it, this voltage is much too high for most 12 volt loads.
At end of discharge, the voltage will as low as 9 volts which is too low for most 12 volt loads.
A 12 volt nickel iron battery certainly wont charge fully/properly from a charge controller intended for lead acid batteries.

Advantages, apart from long life, include tolerance of over discharge and overcharge.
A nickel iron battery could be charged directly from a suitable PV module via a fuse and blocking diode.
The state of charge would need manual observation, with reduction of the charging current when it is nearly full.
MODEST overcharge will do no harm.
No charge controller to fail, though these are now cheap and reliable.
The very variable output voltage would be acceptable for basic emergency lighting useing LEDs.
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sam_uk



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PostPosted: Tue Feb 14, 2012 4:56 pm    Post subject: Reply with quote

mikepepler wrote:
Interesting, but some info on the wikipedia pages shows some down downsides:


I have heard that a lot of the negative claims surfaced as Exide discontinued the batteries in the 1970's. Perhaps they were not making enough cash for the producer and they wanted to write off the technology?

mikepepler wrote:

"Due to its low specific energy, poor charge retention, and its high cost of manufacture,


Sure but if I only have to buy one set in my lifetime, and I have the money now that is quite appealing. I don't really care how big they are, and in a renewable system they will typically not need to hold charge for more than a week before there is more wind/sun.

mikepepler wrote:
they can be damaged by thermal runaway; the cell internal voltage drops as gassing begins, raising temperature, which increases current drawn and so further increases gassing and temperature."


This is more concerning. It is the only reference to it I have seen. Will investigate further..

Adam2 is there anything you don't know about Smile
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adam2
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PostPosted: Tue Feb 14, 2012 5:45 pm    Post subject: Reply with quote

The 10 or 15% self discharge per month could be a significant drawback.
Consider a smallish PV system with a 12 volt 200 A/H nickel iron battery.
That represents a loss of 1 A/H a day, and in winter conditions would require perhaps an extra 20 watts of PV capacity simply to make up the loss.

Constant voltage charging is unwise for the reasons given of thermal runaway. It might be acceptable at a relatively low voltage such as 14 volts, but that would probably never fully charge the battery.
This should not damage the battery, but does mean that some of the very expensive capacity is unused.

The traditional way to charge nickel iron batteries in cyclic use was a relatively large current until the cells start to gas, and then a lower current.
For standby use, a fairly low, roughly constant current was used, with a manually or timmer controlled boost charge after a discharge.
Modest, continual overcharging should not damage the battery but does entail frequent topping up, and also wastes energy.
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RenewableCandy



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PostPosted: Tue Feb 14, 2012 9:44 pm    Post subject: Reply with quote

In answer to that last q., if it's got current flowing through it, he knows all about it Very Happy
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sam_uk



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PostPosted: Wed Feb 15, 2012 10:44 am    Post subject: Reply with quote

Just got a quote for importing 500ah/12 of the Chinese Nickel Iron batteries. They quote 2194 + Vat (423) = 2617
Expected life 21 + years


Compared to 780 for decent quality lead acid http://www.leisurebatteriesireland.com/store/index.php?route=product/product&product_id=56
Expected life 7 years

So they do seem a touch more expensive (300 over 21 year life)

However if they last 80+ years as some of the original cells did..
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SleeperService



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PostPosted: Wed Feb 15, 2012 11:03 am    Post subject: Reply with quote

sam_uk wrote:
Just got a quote for importing 500ah/12 of the Chinese Nickel Iron batteries. They quote 2194 + Vat (423) = 2617
Expected life 21 + years


Compared to 780 for decent quality lead acid http://www.leisurebatteriesireland.com/store/index.php?route=product/product&product_id=56
Expected life 7 years

So they do seem a touch more expensive (300 over 21 year life)

However if they last 80+ years as some of the original cells did..


Especially with those prices I'd look at rebuildable lead acid batteries as an alternative. The plates can be rebuilt relatively easily and the acid filtered for reuse. IIRC submarine or fork lift batteries fit the bill for this. Lead acid is getting a poor reputation due to designed in weaknesses. As soon as the deposits in the bottom reach the plates and short them that cell is dead. Modern batteries have a very shallow gap partly to get more storage capacity but also to ensure regular replacement and revenue for the manufacturer.

The lead acid type you link to I would definately place in the designed for weakness category.
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adam2
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PostPosted: Wed Feb 15, 2012 11:41 am    Post subject: Reply with quote

The older type of lead acid cell with pure lead plates, generous spacing between plates, and a large sediment space under the plates, should last 25 years or more.
These are less readily available than in years gone by, but can still be found. They are properly known as "plante" lead acid cells after the inventor.
They are very bulky and very expensive.

Plante lead acid cells are easy to make and should last at least as well as industrialy made cells.
They will be probably be even bulkier, and still expensive on account of the amount of materials needed.

The making of cells is disscussed here
http://www.powerswitch.org.uk/forum/viewtopic.php?t=8367&highlight=making+lead+acid+battery

Where disscussions may be continued if desired.
Lets try to keep THIS thread on the topic of nickel iron batteries.
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sam_uk



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PostPosted: Wed Feb 15, 2012 5:39 pm    Post subject: Reply with quote

Adam2 can you provide any links to people who manufacturer or sell these 'superior' lead acids?

I do think this is relevant as a comparission regarding the longevity of Nickel Irons..

Paying over the odds for a Nickel Iron battery that is likely to last 25 years + still seems appealing to me. I know I can afford them now. I may not be able to afford a new bank in 7 or 14 years time.

That peace of mind is worth a lot to me, so long as the longevity claims are substantiated.
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mobbsey



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PostPosted: Wed Feb 15, 2012 8:40 pm    Post subject: Reply with quote

I think you're idolising the "technology" of power storage beyond the "purpose" for which it is stored.

When designing a power storage system the specifications are inherently defined by the consumption system it serves. E.g for a home it would be average power consumption during a given period of the year, multiplied by the days of nil-generation you would wish to sustain -- and that nil-generation period is going to be defined by the technology that you are using to create the power (e.g. wind is different from PV, is very different from a hybrid wind/PV system).

Within that calculation process the charging efficiency and internal self-discharge of the storage technology are going to be an integral design factor. You don't fit the technology to the design, you find a technology which matches the design parameters. E.g. nickel iron's high self-discharge might be useless for a PV-powered system, which is prone to long nil-/low-generation periods, but better suited to a micro-hydro system where fluctuations are seasonal but day-to-day generation can be largely constant.

Idolising technology is mental masturbation -- it's the same irrational trait which defines the perceived and planned obsolescence of consumerism. Instead you should understand the purposes for which we might use certain technologies, as often you might decide that "doing nothing" is an equally valid option as employing a specific kind of device, given the factors involved in creating or sustaining that system and the effect that it has on the consumption process.
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sam_uk



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PostPosted: Thu Feb 16, 2012 11:35 am    Post subject: Reply with quote

Fair point mobbsey

I do have a liking for things that are durable. The batteries have always seemed the weak link in a renewable system.

I would be thinking of a solar/wind/TEG system.
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PostPosted: Thu Feb 16, 2012 12:50 pm    Post subject: Reply with quote

mobbsey wrote:
I think you're idolising the "technology" of power storage beyond the "purpose" for which it is stored.

Instead you should understand the purposes for which we might use certain technologies, as often you might decide that "doing nothing" is an equally valid option as employing a specific kind of device, given the factors involved in creating or sustaining that system and the effect that it has on the consumption process.


Good points mobbsey.

I'm currently grappling with a very similar concept in the fight against Ireland being fracked. There's a lot of focus (generated for the supporters' benefit, in terms of distraction of their opponents) on (relatively) minor issues such as fluids being used, acreage, potential 'jobs' etc etc, all the usual gumph.

I point out that these are deliberate ploys frackers use to bog down and exhaust ordinary people, who might then miss the bigger problem, that of energy dependence, particularly fossil-fuel wise, but also generally.

A much bigger, society-wide debate is required, engaging ordinary citizens, over how we are going to leave fossil fuels behind. It's a surprisingly difficult subject for most to grasp!
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Mr. Fox



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PostPosted: Wed Feb 22, 2012 6:09 pm    Post subject: Reply with quote

We obtained a set of 70-odd NiFe cells about 5 years ago, which have since that time served well in an off-grid location (living/workshop). They came out of a hospital UPS system, I believe, and cost us ~150.

As noted above, they like to charge at around 16.5V, so are constantly fed by a ~60W PV module (~17Vpm) via a blocking diode - no charge controller.

There's a 3.5kVA Lister genset that is run for welding or larger machines/tools, so when running it charges the NiFe bank via a 'heavy duty' (22A) charger which luckily had enough space on the transformer secondary to fit a few extra windings to bring the voltage up to around 16.5V.

With pretty much all the lighting now LED, the PV module alone is enough to ensure that there is ALWAYS a bit of light available, even at this time of year. In the summer (with lower demand, etc and without the genny being run), the cells are often gassing by lunchtime.

The main problem is the inverters seeing 'overvoltage' above 15V - the solution to that is to have a 50W halogen lamp next to the inverter that is 'flashed' to drop the line voltage so that the inverter can start. As soon as there is any load, the line drops to around 14.5V.

All in all, they're pretty abuse/idiot proof, which for us is a distinct advantage. Wink

We've never replaced the electrolyte, although this is probably overdue... Anyone here know of a good UK supplier for relatively small quantities of Potassium Hydroxide / Lithium Hydroxide?
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sam_uk



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PostPosted: Wed Feb 22, 2012 11:35 pm    Post subject: Reply with quote

Mr Fox do you remember who you got them off? Very interested if they can be picked up for 150!
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