Nickel Iron vs Lithium Ion Battery from Tesla Motors

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Intro

Good discussion from https://forums.tesla.com/forum/forums/nickeliron-batteries showing the strenghts and weaknesses of Nickel Iron Batteries, archived here.

Thread

Nickel-Iron batteries

Submitted by xxxiter on July 22, 2015

Can anyone explain me, why Elon chose Lithium batteries for stationary power systems, while there are exists Nickel-Iron batteries which are declared to serve at least 50 years?:

http://youtube.com/watch?v=K84PywMwjZg

I understand about the cars: it must be as low weight and quick charge as possible, but these requirements are not a priority for stationary systems!

Dramsey | July 22, 2015 According to Wikipedia:

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

xxxiter | July 22, 2015 This cite looks like justifying, not like true reason. 1) "low specific energy" // Not the priority for stationary system. What prevents us from making 2 "powerwalls" instead of 1? 2) "poor charge retention" // How really poor? If we want to preserve energy just for one night or at most several nights, will be it enough? If you look at permies.com some people use Ni-Fe many years and thay are satisfied with them. 3) "high cost of manufacture" // According to Elon's principle, let's look to the root. Does it contains some rare material, such as lithium? If not, why it should be expensive other than poor technology and low volumes of production? And is it really expensive per one cycle of usage? 4) "other types of rechargeable batteries have displaced the nickel–iron battery in most applications" // It was true in XX century because there was need in a large volumes of starter batteries for cars. And it was as true for ICE cars that they were cheaper, faster and had more range, than electric ones, isn't it?

Grinnin'.VA | July 23, 2015 @ xxxiter | July 22, 2015

>>>This cite looks like justifying, not like true reason.

^^^ REALLY? You are challenging both Tesla's technical expertise in battery chemistry for BEVs and their honesty!

Based on WHAT?!!

DTsea | July 23, 2015 Grinnin, OP seems to have just been pretending to ask a question, as a vehicle for making his statement.

johnse | July 23, 2015 I would say because it leverages their work with the auto systems. If economies of scale allow for lower costs, then increasing the scale makes it moreso.

Further, it has been suggested--but not confirmed--that older cells--no longer with enough charge capability for BEV use, but not requiring recycling yet--may find more years of use in stationary packs.

As for cost, lithium is not really very rare, nor is it expensive. It is not currently considered worthy of reclamation during recycling--though that may change.

Dramsey | July 23, 2015 Seriously, I get so f**king tired of morons who read some article on the latest miracle battery, or some oddity about electrical systems, or something Nikola Tesla is rumored to have done way back when, and then post indignant messages demanding to know why isn't Tesla using this?

Because they're experienced automotive engineers, and you're just some jerk with a keyboard and an internet connection, that's why. Jesus.

xxxiter | July 24, 2015 >>>Because they're experienced automotive engineers, and you're just some jerk with a keyboard and an internet connection, that's why. Jesus.

My question is not about automobiles. So keep you straw man for another case.

>>>You are challenging both Tesla's technical expertise in battery chemistry for BEVs and their honesty! >>>Based on WHAT?!!

I'm an engineer. I don't beleive is anyone's infallibility, either Tesla or Pope. If I don't understand something, I'm just asking a question, like all regular engineers do. The cite of Dramsey doesn't look like compehensive answer. It reflects just someone's version, which is questionable, and above I already explained why.

One of possible reasons for Tesla is unification of manufacturing and recycling of batteries. It can be profitable for Tesla not to diversificate the technonoly (as was mentioned above - economies of scale matters). But it is not necessary the best solution for customer in long term.

EQC | July 24, 2015 >>>> why Elon chose Lithium batteries for stationary power systems, while there are exists Nickel-Iron batteries which are declared to serve at least 50 years?

Batteries are a fast-improving technology...a 50-year lifespan isn't necessarily a good thing. It might be less expensive and more useful to recycle old/inefficient batteries every 15 years and install new ones that work much better. Charge retention, charging efficiency, and charge capacity on new-technology batteries could make the running costs much cheaper as time goes on.

>>>> 1) "low specific energy" // Not the priority for stationary system. What prevents us from making 2 "powerwalls" instead of 1?

Space and weight does matter in something stationary. "2 powerwalls instead of 1" means that shipping/delivery and installation is going to cost more. Additionally, "2 instead of 1" means you're buying twice as much of everything in the system that isn't battery [internal electronics, wiring, case, labor/assembly time, etc.]...raising the effective/total price. And, nobody has "infinite space" on a garage wall to install powerwalls...so "installing 2 instead of 1" translates to "cutting the maximum potential storage capacity in half." All of this must be studied and balanced to optimize the system for functionality vs. cost.

>>>> 2) "poor charge retention" // How really poor? If we want to preserve energy just for one night or at most several nights, will be it enough? If you look at permies.com some people use Ni-Fe many years and thay are satisfied with them.

"Poor charge retention" also translates to "low efficiency" and "wasted energy" and therefore "higher costs of operation." New systems shouldn't be designed just to match the inefficient technology that "some people" accepted when they installed it "many years" ago. Something better is available now, and Tesla doesn't just want to match what "some people" have already been using for "many years"....they want to do something better and appeal to a much wider audience.

3) "high cost of manufacture" // According to Elon's principle, let's look to the root. Does it contains some rare material, such as lithium? If not, why it should be expensive other than poor technology and low volumes of production? And is it really expensive per one cycle of usage?

The name of a battery doesn't tell you everything that's in it. There's probably around 50 pounds of lithium in tesla's ~1000 pound battery pack. It probably doesn't drive much of the cost.

Your quoted text says "high cost of manufacture," not 'high material cost' anyway. Tesla/Elon know the costs of actually building Lithium ion batteries. They work with a partner that is an expert in making Lithium ion batteries, and have worked out how to make huge numbers of them. With Lithium ion, they can hit their price target and production volume goals.

Tesla partners with existing battery manufacturers and works to optimize things for their purposes. If a potential partner was pushing nickel-iron batteries, and could demonstrate superior cost and/or performance and/or mass manufacturing to Tesla, I'm sure Tesla would be interested...but apparently that hasn't happened. Maybe such a partner doesn't exist at all, and maybe there's a good reason for that.

When promoting a random technology, rather than saying "why don't you use this? prove to me it is worse than what you use now!" it might be better to actually prove or show why it is better.

It shouldn't be Tesla's job to work out the manufacturing intricacies of every potential, theoretical, possibly-feasible technology when their Lithium ion solution is already quite workable.

xxxiter | July 24, 2015 >>>"it might be better to actually prove or show why it is better."

One point was shown: almost infinite lifecycle, which in order good for customer, but may be not so good for manufacturer, which may tend to avoid of saturation of market. For the sake of this argument, consider Panasonic made batteries with >3000 cycles, by demand of Tesla: https://goo.gl/oKQcEt . So, they CAN do more cycles, but usually they don't.

Other point, about the cost of production (namely, mass production, including future recycling and possible future deficiency of raw materials), requires an expertise, which available to very few people.

>>>"It shouldn't be Tesla's job to work out the manufacturing intricacies of every potential, theoretical, possibly-feasible technology when their Lithium ion solution is already quite workable."

First, Ni-Fe is not "theoretical". So if you trying to compete something old and established, then it seems good me to prove why new solution (which is, concerning stationary systems, definitely Li-ion, not Ni-Fe) expected to be better. Second, for me as a customer it is worthwhile to choose as sustainabe solution as possible (at decent price), so I do a job, actually, on analyzing the market. If Tesla is interested in critically thinking customers (well, they may be not interested either: the popularity of iPhones even in relatively poor countries gracefully shows the possibility to sell a mediocre goods at premium prices) then it should be not diffucult for them to publish something like FAQ (sure, I'm not alone who asking this question), just to shift discussion to a higher level.

Anyway, it is more worthwhile explanation, than proposition to blindly believe in infallability of Tesla. Especially mentioning of ratio of Lithium (can you provide a proper link?).

EQC | July 25, 2015 For estimates of mass of lithium in a Tesla battery, see the curiousguy | June 20, 2014 comment here:

http://my.teslamotors.com/forum/forums/technical-battery-discussion

He estimates 47 lbs...he could be wrong, but it is obviously true that MOST of the battery weight is NOT lithium.

>>>>One point was shown: almost infinite lifecycle, which in order good for customer.

Not necessarily...it was said above that Nickel-iron batteries don't hold a charge well compared to other options. It costs money, one way or another, to charge up those batteries. If they waste some of it, that is lost money. If they last forever, then you're losing/wasting more money every day forever. Every variety of battery (even the lead acid batteries in cars) get better continually...having a battery that lasts forever isn't useful if using a more efficient option saves enough money to cover the cost of replacement batteries.

Tesla's planned gigafactory has recycling of old batteries built in. Tesla has always planned to repurpose and then recycle batteries as they age, and apparently have the details worked out for lithium ion.

>>>First, Ni-Fe is not "theoretical". So if you trying to compete something old and established, then it seems good me to prove why new solution (which is, concerning stationary systems, definitely Li-ion, not Ni-Fe) expected to be better.

We're not competing "old versus new" we're competing "existing lithium ion solution with proposed nickel-iron replacement." The nickel iron proposal would require the use of less energy dense batteries (taking up more space, costing more to ship and install), and result in a less efficient power storage system (since they don't hold a charge as well). Apparently these batteries have been around for "many years" based on your research, and apparently these problems have not been solved. Tesla is not looking to solve major issues with a decades-old technology when they have a solution that works for their metrics already, and a pathway to further improve that solution.

>>>Second, for me as a customer it is worthwhile to choose as sustainabe solution as possible (at decent price), so I do a job, actually, on analyzing the market.

Most customers in this market would care about the cost of the product including installation, it's running costs/efficiency, how it looks, how long it should last, and how much space it takes up.

Tesla provides the power specs on their batteries -- weight, size, and storage capacity of the power wall, efficiency, peak and continuous power output capabilities, and provides a 10-year warranty with the option to upgrade to an additional 10 years. After 20 years, new batteries will be vastly improved and significantly less expensive, and upgrading will make good sense, whether or not the old batteries have degraded. In his presentation, Elon described the advantages of high energy density for stationary applications. Space, volume, and weight do matter.

Is there some company offering mass production of nickel-iron batteries that can meet these specs and Tesla's demand? Tesla is delivering products in a month...

Nobody "blindly believes in infallability of Tesla" and Elon has repeatedly said that if anybody has a better battery, all they have to do is send a sample to Tesla and it will be evaluated. Internet articles that leave out key specifications while claiming to have a great technology come out every day. Tesla is moving quickly ahead with a solution that works, and have repeatedly said that, given real evidence, they will adopt superior solutions if the become available.

So, perhaps in addition to the low energy density and poor efficiency, the even more important reason why Tesla isn't using Nickel-Iron is because nobody is making the batteries at the enormous quantities Tesla needs.

xxxiter | July 28, 2015 According to my calculation, the volume is not so big issue. Equivalent volume of 10 kWh battery of TN100 cells from ironedison.com is 0.3458 m3 VS 0.2 m3 of 1 powerwall block. Both values are very small relatively of volume of house they assumed to power. But the weight is a big difference: 540 kg of battery of TN100 VS 100 kg powerwall block. But declared usability of 40 years (http://goo.gl/jte0ZH) and theoretically possible decentralized production of DIY kits (to optimize global transportation of heavy filled batteries) keeps the question of preference open (at least for me).

EQC | July 28, 2015 The entire powerwall has a volume of 0.2 m3 and weighs 100 kg...that includes the batteries, any necessary cooling system, electronics, the case, internal mounting structures, etc. Do the TN100 cells themselves take up 175% of the volume of the entire powerwall and already weigh 540 kg?

It sounds like a proposed nickel-iron system would end up about twice as large as a Tesla-designed powerwall, and almost 6 times as heavy. It would not be wall-mountable. We're comparing a 1200+ pound system to one that weighs 220 lbs...for shipping and installation logistics, that is a huge convenience and cost difference.

How much does 540 kg of Nickel-Iron batteries cost, and how does that compare to the $3500 for Tesla's 10 kWh Powerwall?

Perhaps for your application, these things don't matter...but for more wide-spread acceptance, Tesla's solution is probably more appealing to more people.

Tesla offers a default 10 year warranty on their products, with the option to buy an additional 10-year warranty. Most people stay in a home for 6-12 years.

With an over-1200-lb Nickel-Iron battery, for many people, owning it for 40 years would mean hauling it to a new house probably 3-5 times and paying for de-installation and re-installation all over again. If you want to leave it at your old house, what would the new buyer think about the 1200 lb, 20-year old battery on the garage floor?

These things might not matter to you. Most potential battery-pack buyers, on the other hand...

johnse | July 30, 2015 Since the OP has been so insistant that the Ni-Fe batteries are superior, I did some research on both http://ironedison.com and http://beutilityfree.com. This led me to the conclusion that the Tesla solution for stationary storage is significantly better than the Ni-Fe proposition.

First, it is important to compare the correct use cases. The Powerwall comes in two configurations: the 7kWh daily cycle and 10kWh backup. The comparable use case to Ni-Fe is the daily cycle. Iron Edison states, "In general, these cells like to be worked! Charge them up and push your batteries hard with a heavy load. You will find that your battery performs better with heavy use than if you let it sit in float charge."

Therefore, I will compare the 7kWh Powerwall with a 7.2kWh Ni-Fe system. Even with this almost equal comparison in rated capacity, there are notable differences in the configurations:

| Tesla | Ni-Fe | Charge/Discharge efficiency | 91% | 65%-85% | Voltage* | 350-450V | 12-72V | Charge rate | 1C+ ** | .2C | Discharge rate (cont/peak) | .7C / 1C | .25C / 1C | Warantee | 10 years | 10-15 years | Volume | .20 m2 | .34 m2 | Weight | 220 lbs | 484 lbs | Usable capacity **** | 6.3kWh | 5kWh | Cost *** | $3000 | $5820 | Cost / kWh | $429/kWh | $808/kWh | Max system capacity *+* | 63kWh | 48kWh | Cost / kWh at max | $429/kWh | $767/kWh |

  • Tesla Powerwall is designed to have a configurable interface voltage to match common solar systems being used in grid-tie environments. The Ni-Fe solutions are based on single (or at most 2-parallel) strings of high amp-hour cells. The lowest capacity cells are 100Ah allowing for 72 of these to be strung in series for 7.2kWh (though both sites only list up to 48V solutions). 24-48V systems are commonly used for off-grid today. The specifics that I am using for sizing are a 24V system with 300Ah cells.
    • Could not find this information specifically for Powerwall, but the Panasonic cells clearly have charge capacity above 1C.
      • Tesla includes BMS. Ni-Fe is batteries only
        • Max discharge of Tesla automobile battery packs reserve 10% SOC for battery health, giving a usable 90% of rated capacity. Ni-Fe should not be discharged below 20% SOC and are very inefficient during charging in the 80-100% range. Thus I'm guessing 70% usable capacity.
  • +* 9 powerwalls in parallel vs. largest 48V system (largest listed on supplier's site). Note that for larger systems, Powerpacks start at 100kWh, but if I recall correctly requires a minimum of 5 packs at $250/kWh.

Ni-Fe is a wet cell technology. It requires frequent watering to keep the electrolyte levels in the correct range Ni-Fe electrolyte must be replaced periodically (3-7 years, depending on how well cared for.) Ni-Fe off-gasses hydrogen and oxygen during charging, especially in the 80-100% SOC range