More on Nickel Iron batteries….

24 07 2018

You read a lot of rubbish on the internet about batteries. It’s usually written by people who have very little experience with them too… for instance…:

The BIG reason to NOT buy NiFe batteries is they are incredibly expensive, they are charging you 9x the price of a lead acid and guarantying you only 5x the life. 

In reality, a Nickel Iron battery costs about double the price of a good Lead Acid battery. For example, a 12V, 300Ah Giant Power Sealed AGM Lead Acid Battery cost $669.00 online. This battery is rated at 1,850 cycles @ 30% DOD, which is 5 years. A comparable Nickel Iron Battery would be an Ironcore 12V, 200Ah battery rated at 7200+ cycles, which is 20+ years. This battery will cost you $1480.00……  and in reality give you more capacity than the above. It’s difficult to make a proper comparison, because in truth we’re comparing apples with oranges here….

So, if you are off grid and using your battery everyday, over a 20 years period you would have to replace that lead acid battery bank 4 times, and maybe 5 times….. With Nickel Iron you will never have to replace the battery, so over a 20 or more year period, you would have definitely saved money. More importantly, there will come a time it will be impossible to even replace the batteries!

NiFe batteries are VERY inefficient, which means a significant fraction of the energy you put in, does not get stored, something like around 25%. 

I am going to break this down into 2 parts. First, we are going to talk about Nickel Iron Battery efficiency, and then we will talk about Lead Acid Battery efficiency.

Nickel Iron Batteries are about 75% Efficient. The cells have been tested at the National Renewable Energy Laboratory, and below are the results. Overall at normal temps, they out performed their rated capacity between 75-80% efficiency.

Lead Acid Battery Efficiency – Below is a link to the Sandia National Laboratories results on Lead Acid Battery Efficiency. According to this document, they found out that when you are only using the top 20-30% of a battery, it really only has a charge efficiency of 55%.

So after looking at the actual data – the nickel iron battery is more efficient than a lead acid battery in daily off-grid charging, because you can discharge them as much as you like, and as often as you like without causing any damage whatever…. living with NiFe batteries is a completely different mindset that took me ages to get used to!

They are VERY VERY gassy, that is why there is such a huge head space on them to hold SO MUCH extra water, which MUST be distilled water ONLY. 

Nickel Iron Batteries do off-gas a little more than a lead acid battery, but this is because of the differences in the batteries’ chemistry. Both a wet lead acid and nickel iron battery require to be put in a battery box and I recommend using a vent fan or a whirly bird or two as I did in my container station.

The Nickel Iron Battery produces hydrogen when the battery pushes the oxygen from the water molecule to increase the oxygen concentration on the nickel plate. The head space is not huge on a nickel iron battery, but you do want an area for the electrolyte so you are not having to fill the battery with distilled water all the time. In my experience, I have to top my batteries up three times a year which takes about 20 minutes… 1 minute per cell.

A wet lead acid battery produces hydrogen through inefficient charging, when the electricity not used from charging is spent on splitting a water atom.

Both a wet Lead acid battery and Nickel Iron Battery use distilled water only. A sealed lead acid battery does not need water and does not off-gas, but has a much shorter shorter life if cycled everyday…..  or even if not cycled every day. I had sealed lead acid batteries in Cooran that were floated all day long that lasted just long enough to go out of warranty which was two years! A friend of mine in Queensland bought better quality ones that lasted six years….

They have a high rate of self discharge, so if you just leave them there, they can loose 10% or more of their charge PER DAY.

I reality, Nickel Iron Batteries have a 1% self discharge rate. If you are wanting a battery that will just sit there and not be used, then you might want a sealed lead acid battery. Sealed lead acid batteries are good for people that are not using their battery and want it to just sit there and hold its power in case the power goes out once a year or so…. personally, I think that’s a waste of time money and resources, last time I did this the batteries lasted just two years….

If you plan on using your battery every day, it really does not matter if it discharges 1%, because you are going to charge up the battery and use the batteries power next day. In my experience, that overnight loss is regained in the first twenty minutes after sunrise, so it’s a non argument……

edison EV

Thomas Edison with early EV

Of late, I have been thinking more and more about an eventual conversion of my trusty 4WD Bravo to electric drive. Never forget that NiFe batteries were originally invented for the very purpose of driving electric cars at the turn of the 20th Century……

Ironcore, from whom I bought the powerstation’s battery bank, sell 12V 10Ah batteries (actually 10 x 1.2V cells connected together) for $270. To achieve 120V por motor power, I’d need 10 of those giving me a capacity of 120V x 10 Ah = 1.2kWh or barely what’s in a litre of petrol! The old ute would go about 10km on that amount of fuel, but as electric motors are twice as efficient (or more) than ICE’s, it’s more likely it would go 20km. Furthermore, because NiFe batteries can be discharged far more than other types, it’s possible the ute would actually go farther, but of course that’s hard to predict…

Image result for 12V ironcore battery

10 of these connected together make a 12V battery

By having two such banks in parallel would double the range, which is probably about as far as I would need to go, especially after everything’s shut down from lack of fuel! Gathering firewood would almost certainly be its biggest task, and the forest is not very far away at all.

Out of the blue, an article about enthusiasts like me converting ICE cars to electric drives came up on out ABC internet website, which is what prompted me to write this while spending time in Queensland, supporting my better half looking after her 94 year old mother while the Tasmanian winter weather does its thing…. and the prime subject of these conversions is a ute, though unfortunately, while the batteries are mentioned, they are not shown, so I have no idea what this guy used… there’s a video at the link.



17 responses

24 07 2018
Bruce Teakle

Thanks for this post Mike – you should drop in while you’re in Qld!
On lead acid battery efficiency: I totally agree. Especially with flooded cells, efficiency isn’t such a big part of system design. You need to have enough PV capacity, it looks to me like at least about C/20, to equalise and gass your batteries well enough to avoid stratification, regardless of how much energy you need. Thus big batteries with small arrays die of stratification, even if there is enough PV input to cover daily loads.
Re electric cars: we do need transport for goods, but electric cars are a terribly expensive way to do this. My electric cargo bike uses between 5Wh and 20Wh per kilometre, depending on hill climbing and load. It’s so much cheaper in capital and running cost than a car, yet we see endless talk about how to maintain the driving culture in an energy constrained future. Most of the time, the personal electric car is the wrong answer to the wrong question. The community electric ute is more likely to be a goer.

24 07 2018

Like I said above, I need to be able to carry a tonne of firewood, at least until I have enough trees growing on our farm…. and I don’t think a cargo bike will cut it, especially at my age… 🙂

24 07 2018

Hi Mike, the batteries used by the guy in the linked article are Winston Lithiums, there is a full write up on a site called The Back Shed or TBS.
For some reason I cannot do a link.

Bruce, it depends on what you carry and how far for electric bikes, but for me a heavy duty electric trike is the answer, but one with a steering wheel as my shoulder will not work a set of handle bars.
With some panels over the cargo area it would be useable all day.

24 07 2018
25 07 2018

Capacitors realy need to be part of the storage mix. Capacitors can withstand many times the number of cycles, orders of magnitude more. Capacitors can provide massive rates of dischange and charge up so quickly. Capacitors store much more per unit size.

However capacitors are only short term storage, you will still need batteries. A super capacitor will discharge 50% to 100% in a month. Capacitor voltage drops as it discharges, much more than a battery does, so you need better regulators. You will need an output regulator.

Even with capacitors Tesla cars suffer from battery overheating with fast acceleration regeneration cycles, more capacitance would help. Stator overheating is still a problem that capacitors wont fix and which renders the Tesla useless in much of Australia (useless may be an overstatement but that huge performance will not be available)

25 07 2018

“Huge performance” is not something we should be chasing in a limits to growth scenario……

26 07 2018

My point wasn’t so much we need massive performance but major limiting factors of deep cycle batteries are their draw rate and limited cycles. Capacitors could extend the life of batteries and reduce how many batteries are needed. In some cases the size of the battery pack is determined more by the rate than the total storage.

Just as batteries have improved in performance and got cheaper, the same is happening with capacitors.

Downside is compexity. While the capacitor is simple the associated electronics are less so.

25 07 2018

Excellent Mike, thanks for this. Bookmarked for future reference.

26 07 2018

Hi Mike…are your batteries Ironcore….I seem to remember yours came from Russia. Are you still using rainwater. My rainwater is slightly acidic…apparently mild carbonic acid formed during rainfall by dissolving CO2…I have to neutralise it in my aqua ponics system. The electrolyte in the iron core batteries sounds a lot more complicated with Lye solution and lithium.

26 07 2018

Hi Sean, yes they are Ironcore, but they came from China, I mistakenly thought they’d be Russian….. David Bartlett from Ironcore recommended not putting the Lithium in the electrolyte, so I didn’t. The mixing of the electrolyte is not so much difficult as time consuming, because you have to do it slowly or kill yourself! Just joking….. but it took me 3 or 4 days from memory to fill my 40 cells….

I haven’t reached the water tank stage, and only recently discovered rainwater is slightly acidic…. a friend of mine who stores their rainwater in concrete tanks had problems with the acid attacking the joints in their Besser block tank causing leaks, but I’d never heard of this before.

4 08 2018

All my tanks have a noodle basket, filled with limestone chips, hung by wire (all 316 stainless) under the inlet strainer… alkalises the water nicely. I reckon it tastes better, and its healthier too! Something like this might help your friend with the besser block tank?

I think distilled water is supposed to be neutral, but as Sean noted, once it touches air, dissolved CO2 will drop the pH. Do NiFe’s have a preferred water pH?

And how much water do you use each top up Mike? And are you just buying it, or distilling it yourself? I recall an old forum thread where some guy called himself the “Water Boy” he was doing it that often!

Also, my understanding is with the Lithium, you should get about 10% more out of the battery… why wouldn’t you put it in?

My cheap GEL batteries are still holding up (surprisingly) well, but I expect to be getting my NiFe’s in the next few years, so I appreciate your insights into living with ’em Mike!

26 07 2018

Thanks for reply….a battery bank is next on my list and few people have heard of NiFe. Lye could me made from wood ash at a stretch but I don’t think lithium will be easy to come by.

26 07 2018

I can’t remember why David said to not add it, but he is VERY knowledgeable and will talk you ears off if you let him. It’s actually great to get good support and advice for a change…

4 08 2018

Tom Murphy of “Do the Math” fame has recently posted this…:

In other news, my Nickel-Iron batteries seem to be holding up well (I owe a post on some real analysis of these). I am “living the dream” in my daily commute. After 12 years off a bike (obvious routes are dangerous; hilly profile would require time-inefficient shower), I finally solved the problems: (longer) trail route and an e-bike (off-grid-solar-charged). Purists would say I’m cheating, but I say I’m back on a bike and working plenty hard. The rough-hewn route exposes me to wildlife (the occasional coyote or bobcat, even), has a few stream crossings, and enriches my life by offering a daily connection to the natural world. My propulsion energy is now free of direct contributions from fossil fuels, which I find to be rewarding—even if the materials/manufacture are still utterly dependent.

I keep ckecking his website for an update, and wait with bated breath….

19 09 2018

I heard a comment there was a company in Australia manufacturing Nickel Iron Batteries . Is that true ? If so is there anyone to contact that could revive production of the anode and cathode plates ?

20 09 2018

It’s news to me…….

18 12 2018

Its expensive but longest lasting battery.

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