I will replay to the post by SemiMan in CAPS between lines as requested ... I did not reply to it earlier.
IT WOULD SEEM THAT SOME LEAD ACID BATTERY USERS HAVE AN ALMOST RELIGIOUS BELIEF IN THEIR MERIT. EACH BATTERY DESIGN IS NOT BETTER THAN ANOTHER ... THEY HAVE DIFFERING PROPERTIES THAT MAKE THEM IDEAL FOR SOME APPLICATIONS AND NOT GOOD FOR OTHERS. NICKEL IRON HAPPENS TO BE IDEAL FOR RENEWABLE ENERGY STORAGE. LEAD ACID BATTERIES CAN BE USED IF YOU ARE PREPARED TO REPLACE THEM AT REGULAR INTERVALS AND DISPOSE OF THE OLD BATTERIES IN THE CORRECT WAY. THIS MAKES LEAD ACID BATTERIES A CONSUMABLE ITEM WITH A SHORT LIFE. LOTS OF PEOPLE IN THIS FORUM HAVE HAD EXPENSIVE AND UNPLEASANT ISSUES RELATING TO LEAD ACID FAILURES.
THE MAIN NEGATIVE ASPECT OFNICKEL IRON BATTERIES IS THEIR LOW CURRENT CAPACITY ... BUT WITH GOOD DESIGN THIS IS NOT AN ISSUE OF CONCERN. 200 AH NICKEL IRON BATTERIES CAN DELIVER 50 AMPS OF CONTINUOUS CURRENT EASILY. THE DESIGN RULE IS TO USE A FACTOR OF 4 (200/4=50).
I consider any article that only promotes the positive aspects of a technology and does not consider the negative aspects to be either a) Propaganda or b) Sales Material
So, I will take the WHY NOT side of Nickel Iron:
1) Comparatively terrible charge/discharge efficiency. Currently best case 80%, but typically in the 65% range. That is a major hit on the solar house side. Good quality AGM batteries hit 90%+ efficiency (with Lithium chemistries 90+).
THE CHARGE / DISCHARGE EFFICIENCY OF NICKEL IRON BATTERIES STARTS LOWER AT AROUND 60% AND RISES FOR THE FIRST 2 YEARS TO ABOUT 80% . EDISON DID 3.5 MILLION DOLLARS IN RESEARCH BETWEEN 1902 TO 1910 WHICH MAKES IT ONE OF THE MOST HEAVILY RESEARCHED OF ANY BATTERY DESIGN. EDISON STATED THAT THE IMPROVEMENT IN EFFICIENCY CONTINUES TO RISE SLIGHTLY FOR ANOTHER 4 YEARS.
IN COMPARISON, LEAD ACID EFFICENCY DECLINES AFTER THE FIRST YEAR STEADILY.
2) Poor low temperature performance.
I AM USING MINE OUTSIDE IN A GARDEN SHED WITH THE AVERAGE TEMPERATURE SITTING AT 5 DEGREES C MOST OF THE WINTER. I MIXED MY ELECTOLYTE TO SUPPORT DOWN TO MINUS 20 DEGREES C BUT I COULD HAVE MIXED IT FOR OPERATION AT MINUS 40 DEGREES C. NICKEL IRON BATTERIES WILL NEVER FREEZE AT ANY TEMPERATURE SEEN ON EARTH. OPERATIONAL RANGE FOR THE LAST CENTURY OF NICKEL IRON BATTERY USE HAS BEEN MINUS 40 CENTIGRADE TO PLUS 46C. THEY HAVE NO PROBLEM WITH LOW TEMPERATURES.
LEAD ACID ON THE OTHER HAND IS SERIOUSLY DAMAGED IF THEY HAPPEN TO DISCHARGE. SO IF YOU HAD A COTTAGE ON SOLAR AND THE PANEL / CONTROLLER SYSTEM FAILED AND IT WENT BELOW ZERO THE BATTERIES WOULD BE DESTROYED. IT IS LEAD ACID BATTERIES THAT SUFFER
3) High internal resistance / poor high rate performance. This often results in requiring a larger battery bank to meet high load requirements.
THIS IS A DESIGN PARAMETER THAT NEEDS TO BE LOOKED AT CAREFULLY WHEN SELECTING NICKEL IRON BATTERIES. AS A RULE OF THUMB YOU NEED TO SELECT AN AMP HOUR RATING THAT IS EQUAL TO 4 TIMES THE PEAK AMP DELIVERY NEEDS. FOR EXAMPLE IF YOU NEEDED 50 AMPS AT ONCE THEN 200 AMP HOUR NICKEL IRON BATTERIES WOULD BE USED. IF YOU NEEDED 250 AMPS THEN YOU WOULD CHOOSE 1000 AH BATTERIES.
THIS VERY SAME CHARACTERISTIC THAT LIMITS MAXIMUM CURRENT DELIVERY IS THE SAME MECHANISM THAT PRODUCES THE INCREDIBLY LONG LIFE OF THE NIFE CELL.
4) Typically not maintenance free (but neither are the longest life lead ACID). That said, the Nickel Iron does take more maintenance.
TO BE ACCURATE THE TYPE OF MAINTENANCE NEEDED IS SIMPLY THAT DISTILLED WATER NEEDS TO BE ADDED EVERY 2 MONTHS. I ADD 50 ML OF WATER TO EACH CELL EVERY 2 TO 3 MONTHS. CHANGHONG HAS COME OUT WITH TWO LEADING EDGE (RELEASED LAST MONTH) OPTIONS. THEIR NEW SOLAR NICKEL IRON BATTERY HAS FOUR TIMES THE STORAGE AREA FOR ELECTROLYTE SO THAT YOU ONLY HAVE TO WATER THEM 2 OR 3 TIMES PER YEAR. THEY ALSO MAKE A CATALYTIC CAP THAT RECOMBINES THE H2 AND O2 INTO WATER SO THAT YOU NEVER HAVE TO FILL THEM. THESE ARE AVAILABLE ALSO FOR LEAD ACID BUT IN THAT CASE THE SULPHUR CONTENT OF THE LEAD ACID BATTERIES WILL DESTROY THE PLATINUM CATALYTIC CAPS OVER 4 TO 5 YEARS. NIFE BATTERIES CONTAIN NO CATALYTIC POISONS SO THEY SHOULD WORK FOR DECADES WITHOUT LOSING WATER. THESE CATALYTIC CAP VERSIONS ARE IN TESTING RIGHT NOW AT CHANGHONG BUT THE SOLAR ONES ARE FOR SALE NOW. CHANGHONG IS HOPING TO TAKE OVER THE EUROPEAN MARKET FOR FLOODED NICKEL CADMIUM CELLS WHICH ARE WIDELY USED IN INDUSTRY BUT ARE ABOUT TO BE BANNED BECAUSE OF THE CADMIUM. NIFE IS A PERFECT REPLACEMENT BECAUSE THE CHARGE SYSTEM AND MOST OF THE CHARACTERISTICS ARE THE SAME AS AN NICAD DESIGN.
WORTH LOOKING AT NEW RESEARCH FROM 2005 IN INDIA ... LISTED ON THE NICKEL IRON BATTERY ASSOCATION SITE. THEY SUCCEEDED IN PRODUCING A SEALED NICKEL IRON BATTERY FOR THE FIRST TIME IN HISTORY.
5) Currently expensive (maybe volume can fix that?)
THIS WILL NOT BE FIXED BY QUANITITY MANUFACTURING BECAUSE NICKEL IS 10 TIMES MORE EXPENSIVE THAN LEAD. IF THE NIFE BATTERY EVER FAILS, MOST OF THE COST WILL BE RECOVERED DURING RECYCLING WHEREAS YOU WILL ONLY GET ABOUT FIVE BUCKS FOR AN OLD LEAD BATTERY. NIFE IS 1/2 NICKEL AND 1/2 IRON BUT IRON IS WORTHLESS SO YOU CAN SEE THAT THEY WILL ALWAYS REMAIN AT THE 4 TO 5 TIMES HIGHER COST.
6) So so energy density and as above, poor power density.
THE POWER DENISITY IS IRRELEVANT FOR SOLAR AND RENEWABLE APPLICATIONS. EVEN THOUGH NICKEL IRON WAS USED IN EARLY CARS FROM 1912 THEY ARE NOT RECOMMENDED FOR THIS APPLICATION. FOR BOATS NICKEL IRON BATTERIES ARE FINE. THEY HAVE ABOUT THE SAME POWER DENSITY AS LEAD ACID. SOME OF THE NEWER DESIGNS HAVE ACHIEVED NOT MORE THAN A 30% IMPROVEMENT.
IN THE BASEMENT OF A HOME OR GARDEN SHED ... NO ONE CARES ABOUT THE POWER DENSITY.
Nickel Iron does not have infinite deep discharge. 2000-3000 cycles is what I typically see quoted. This is very good, but not infinite. That said, an electrolyte recharge can recover capacity so that is quite interesting. They have great float capacity.
NICKEL IRON CAN DO ABOUT 1000 DEEP DISCHARGES TO ZERO VOLTS. LEAD ACID CANNOT SURVIVE EVEN ONE OF THOSE KIND OF MISTAKES. I LOVE NIFE BECAUSE I NEVER NEED TO WORRY ABOUT ANYTHING GOING WRONG.
NOW THE PROPER WAY TO DESIGN AN NIFE BATTERY SYSTEM IS TO OVERSIZE IT SO THAT THE MAXIMUM DEEP DISCHARGE IS ONLY 40% OR LESS. IN THIS CASE WE CAN GET UP TO 10,000 CHARGE DISCHARGE CYCLES. AS STATED IT IS TRUE THAT OLD CELLS THAT ARE 30 TO 50 YEARS OLD CAN OFTEN BE PUT INTO USE AFTER WASHING THEM AND CHANGING THE ELECTROLYTE. LOOK AT THE CHICAGO OFF GRID HOME USING NIFE BATTERIES ... THE GUY USED HERITAGE BATTERIES MADE BY EDISON'S COMPANY EXCLUSIVELY.
http://nickel-iron-batteries.com/comparisons.htm ... is full of errors .... let's look at some of the errors:
* A Nickel-Iron cell can last well over 20 years in robust service if properly maintained. Lead-Acid cells are lucky to last 15 years in light duty.
- Expensive Lead-Acid batteries last 10 years in fairly heavy service ... and they are still cheaper than Nickel Iron
(NONE OF THESE ERRORS WERE ERRORS) THE NAME OF THE GAME IN RENEWABLE ENERGY IS TO FIND BATTERIES THAT ARE BOTH NON TOXIC AND ROBUST.
I KNOW THREE RENEWABLE ENERGY COMPANIES IN VICTORIA WHO ALL ADMIT THAT THE WEAKEST PART OF ANY SYSTEM IS THE LEAD ACID BATTERIES. THEY STATED THAT 10 YEARS IS ONLY ACHIEVABLE IF ONE NEVER MAKES A MISTAKE. WITH NIFE WHO CARES IF YOU MAKE A MISTAKE AND OVER DISCHARGE OR OVER CHARGE IT A FEW HUNDRED TIMES. IT JUST DOES NOT MATTER. I HAVE RUN MY SYSTEM FOR A FEW WEEKS WITH NO CONTROLLER AT ALL WITHOUT ANY PROBLEM.
* Nickel-Iron cells wont sulphate if left in a discharged state, unlike Lead-Acid cells.
- This is true, but since this site is heavily focused on Solar, when is a battery in a solar system ever left discharged for any length of time?
ELECTRONIC FAILURE IS NOT UNCOMMON. WOULD IT NOT BE GOOD TO KNOW THAT NOTHING BAD CAN HAPPEN IN ANY CASE?
* Nickel-Iron cells have a wider operating temperature range than Lead-Acid cells.
- What??? AGM lead acid batteries are good to -40C well beyond the useful temp of Nickel Iron.
NICKEL IRON BATTERIES ARE ALSO GOOD TO MINUS 40. READ ANY MANUAL ABOUT MIXING THE ELECTOLYTE. TEMPERATURE RANGES OF MINUS 40 TO PLUS 46 DEGREES C CAN BE ACHIEVED BY DIFFERENT MIXES ... SIMILAR TO LEAD ACID BATTERIES IN THE TROPICS WHICH USE A DIFFERENT CONCENTRATION OF SUPHURIC ACID. I WAS UNAWARE THAT LEAD ACID COULD MATCH THE LOW TEMPERATURE OPERATION OF NICKEL IRON. THIS MIGHT BE A MISTAKE IN THE ARTICLE TO SAY THAT LEAD ACID CANNOT WORK AT LOW TEMPERATURES. OF COURSE IF LEAD ACID ONES LOSE THEIR CHARGE AT MINUS 20 C THEY WOULD BE COMPLETELY DESTROYED.
* Nickel-Iron cells have a higher self discharge rate of up to 40% a month compared to Lead-Acid of 5% a month and Nickel-Cadmium of between 2 and 20% a month.
THIS IS WHAT MAKES NICKEL IRON IDEAL FOR SOLAR APPLICATIONS BUT NOT FOR CARS. THEY LOSE IN REALITY ABOUT 1 % / DAY. WITH DAILY SOLAR / WIND CHARGING THIS IS A NON ISSUE. FOR STARTING A CAR IT IS AN ISSUE BUT THAT IS NOT WHAT NICKEL IRON BATTERIES ARE USED FOR. THEY ARE AN APPROPRIATE TECHNOLOGY FOR RENEWABLE APPLICATIONS.
- Good quality lead acid are closer to 2% per month but not important
* Over charging will not cause damage to Nickel-Iron cells. Unlike Lead-Acid cells.
- In this day of good quality chargers, especially for solar systems, overcharging does not happen.
AGAIN ... ACCIDENTS ALWAYS HAPPEN. GREAT TO KNOW THAT IF YOU DISCHARGE YOUR NIFE BATTERY BY ACCIDENT ONCE YOU HAVE 999 LIVES LEFT! WITH LEAD ACID IT IS TIME TO BUY ANOTHER ONE. PLUS THERE IS THE WORK AS WELL AS THE COST OF REMOVING 1000 POUNDS OF BATTERIES AND PUTTING IN NEW ONES. COST HAS TO INCLUDE THE LABOUR.
* Amp hour capacity for Nickel-Iron cells is rated over 5 hours rather than 100 or 120 hours for Lead-Acid cells. If Nickel-Iron cells are rated over 100 hours they would measure around a 20% increase in capacity. If any battery type is discharged slowly it gives up more amps than if it is discharged quickly.
- Lead Acid batteries for solar systems are typically shown at C/10 if not C/20 rates worst case.
IT IS TRUE THAT THE NICKEL IRON BATTERIES ARE RATED IN A MORE CONSERVATIVE AND MORE HONEST WAY. THIS MIGHT LEAD TO THEM SEEMING LESS EFFECTIVE.
For Solar, a C/100 rate is also provided as this is common in solar. That said, Lead-Acid has lower internal resistance hence is better at high discharge.
- There are so few commercial Nickel Iron batteries on the market (almost none) that making a blanket statement that Nickel Iron cells are rated at C/5 is completely meaningless
THEY ARE PRODUCED IN THE MILLIONS / YEAR THROUGHOUT EUROPE AND ASIA. THEY ARE ALWAYS RECOMMENDED TO BE CHARGED AT 1/4TH OF THEIR CAPACITY IN AMPS. IT HAS BEEN STATED THIS WAY SINCE ABOUT 1914 ... AND IS ALSO STATED THIS WAY IN MODERN MANUALS BY CHANGHONG.
* Nickel-Iron cells can be fully charged in 5 to 7 hours without harm - unlike Lead-Acid cells. If a generator is used to charge the batteries this can mean less running time.
- AGM lead ACID can be charged at very high currents, much higher than Nickel Iron. Same for many high quality for solar batteries. Nickel Iron tends to create a lot of hydrogen which one must be careful with.
ACTUALLY THEY CAN BE CHARGED IN 5 HOURS. IN THE NICKEL IRON WORLD THIS MEANS THAT FROM ZERO VOLTS YOU CAN ACHIEVE A FULL CHARGE. FOR EXAMPLE IF A NICKEL IRON 200 AMP HOUR BATTERY IS USED THEN THE MAXIMUM CHARGE RATE IS 50 AMPS AND THEORETICALLY IT MIGHT CHANGE IN 4 HOURS. BUT INEFFICIENCIES MEAN THAT IT TAKES 5 HOURS.
IT IS THE INITIAL CONDITIONING CHARGE THAT CAN TAKE SEVERAL DAY. THIS IN ONLY NECESSARY ONCE WHEN YOU BUY THE BATTERIES. AFTER THAT A 5 HOUR CHARGE WORKS.
* Battery capacities change over time. Brand new Nickel-Iron batteries put straight to hard work in deep discharges have a 20% lower capacity than their rating, increasing rapidly to 100% or better (in a month or so) then gradually reduce in capacity over the years to stabilize at over 70% of rated capacity. Lead-Acid batteries tend to have a lower capacity when new, increase for a few months then decrease slowly but continuously for the rest of their life.
IT WOULD BE A POOR DESIGN OF AN NIFE BATTERY SYSTEM IF IT WERE DEEP DISCHARGED TO ZERO. NORMALLY THEY MAINTAIN THEIR RATING FOR AT LEAST 20 YEARS (WHEN CONSERVATIVELY CYCLED) AND THEN SLOWLY GO DOWN FROM THERE. ELECTROLYTE REPLACEMENT OF NIFE BATTERIES IN EXCESS OF 50 YEARS OLD RESULTED IN USEABLE BATTERIES THAT WERE REDUCED TO ABOUT 60% OF THEIR ORIGINAL CAPACITY. THE INDUSTRIAL DEFINITION OF THE END OF LIFE OF NIFE IS WHEN IT ONLY ACHIEVES 70% OF CAPACITY. BUT THOSE EXPIRED BATTERIES CAN STILL DO USEFUL WORK FOR MANY DECADES.
- Nope, Nickel Iron degrade too unless the electrolyte is recharged
OF COURSE WITH LEAD ACID THE BATTERY IS SHOT PERIOD ... CHANGING THE ELECTROLYTE WILL BRING THE LEAD ACID ONE BACK TO LIFE FOR A BRIEF PERIOD BUT IT WILL ALWAYS HOLD ONLY A MUCH SMALLER CHARGE THAN ITS ORIGINAL DESIGN OFFERED.
* With Nickel-Iron cells the full available capacity can be utilised when calculating battery size for solar systems. After years of use available capacity should stabilise at about 70-80% of rated capacity. Lead-Acid batteries are always over sized in solar systems usually by 2 to 5 times to avoid deep discharging.
- Actually batteries for solar systems are sized for 5-10 days of storage and when dealing with Lead-Acid, typically a 20% reserve is kept for deep discharge knowing that in reality, this should rarely be tapped. No one over sizes by 5 times to avoid deep discharge. 50% over sizing I have seen occur but never for home systems where "must have" power is needed. It is more for convenience systems.
I HAVE SIZED MY NICKEL IRON BATTERIES TO 50%. HOW GREAT IT IS TO KNOW THAT IF THE SUNSHINE FAILS FOR AN EXCESSIVE TIME THERE IS NO PROBLEM WITH GOING FOR A MUCH DEEPER DISCHARGE ... WITH NO NEGATIVE CONSEQUENCES. DEEP DISCHARGES ARE TO BE MINIMIZED BUT CERTAINLY NOT TO BE AVOIDED SINCE YOU ARE ALLOWED A THOUSAND DEEP DISCHARGES.
* The charge pattern of solar panels matches perfectly with the charge pattern of Nickel-Iron cells. Because of this Nickel-Iron cells can be used in a solar system without a charge regulator. All Lead-Acid cells used in a solar system should be charged through a charge regulator to avoid damage through over charging.
- Ya right! Of course you need a charge regulator to match panel to battery voltage. ESPECIALLY with Nickel Iron batteries where you already have very poor charge/discharge efficiency. In fact you really need an MPPT controller to maximize the charge efficiency. Nickel Iron has a very wide operating voltage range that needs to be matched for any tolerable efficiency.
I RAN MINE FOR TWO OR THREE WEEKS WITH NO CONTROLLER AT ALL. NOT HARD TO DO ... I USE 22 CELLS TO A NOMINAL VOLTAGE OF 26.4 VOLTS. EQUALIZATION VOLAGE IS 36.4 VOLTS. I USED 40 VOLT PANELS AND THEY SIMPLY COULD NOT DELIVER CURRENT AT 40 VOLTS. THEY CHARGED PERFECTLY TO AN EQUALIZATION VOLTAGE EVERY TIME BUT WITH NICKEL IRON YOU CAN DO THAT EVERY CHARGE IF YOU WANT. I KNOW IT SEEMS STRANGE TO SAY YOU CAN RUN THEM WITHOUT A CONTROLLER BUT FROM EXPERIENCE I KNOW THAT THIS IS TRUE! MANY HAVE WRITTEN ABOUT THIS.
THERE WAS A DOWN SIDE THE CAUSED ME TO BUY A MPPT OUTBACK CONTROLLER. WHITHOUT A CONTROLLER THE LEVELS OF WATER GO DOWN FAST. I GOT TIRED OF TOPPING IT EVERY WEEKS! YOU CAN DO IT BUT YOU CREATE WORK FOR YOURSELF.
PLEASE FEEL FREE TO RESEARCH ANY OF THIS INFORMATION ... IT IS NOT HARD TO FIND. THE GUY IN CHICAGO THAT DID A LARGE NIFE BACKED OFF GRID HOUSE DISCUSSES THE TECHNICAL DETAILS OF HIS HOUSE BUILT ABOUT 15 YEARS AGO. HE USED MOSTLY RECYCLED NICKEL IRON BATTERIES HE GOT FOR FREE AND RECONDITIONED THEM BY WASHING AND REFILLING. MOST WERE 30 YEARS OLD AND SOME WERE MUCH OLDER.
I ALSO HATE MISINFORMATION AND THERE SEEMS TO BE A LOT FLOATING ABOUT. ESPECIALLY CONCERNING NICKEL IRON BATTERIES. OF COURSE THE EXIDE LEAD ACID BATTERY COMPANY PROMOTED THE BELIEF THAT NIFE BATTERIES WERE POOR IN 1975 WHEN THEY HAD TO JUSTIFY THE ACQUISITION OF THE EDISION NICKEL IRON STORAGE BATTERY CO IN 1972 FOR SOME 200 MILLION DOLLARS ONLY TO ABANDON THEM 3 YEARS LATER. THE REAL REASON WAS THEIR LONG LIFE.
HERE IS A MODERN NICKEL IRON BATTERY MANUAL THAT SUPPORTS CHANGHONG BATTERIES NEWEST SOLAR VERSION. ANOTHER MANUAL COMING FROM THE RUSSIAN KURST ACCUMULATOR WORKS IS ON ITS WAY.
http://microsec.net/Solar Nickel Iron battery.pdf
I am not saying Nickel Iron does not have potential, but I hate misinformation!
