Zenaji Batteries: Will People Pay More For A 20-Year Warranty?

Zenaji aeon battery

The black tubes are the Zenaji Aeon battery. They offer a 20 year replacement warranty and cost $1,500 per kWh. Image: Zenaji

Australian battery vendor Zenaji is getting ready for what it hopes will be a ramp-up for lithium titanate batteries, which it says in home and grid storage applications offer better lifetime, safety, and value for money than the more popular and familiar lithium-ion chemistries.

Zenaji CEO Dawson Johns told SolarQuotes the first batches of its 48V, 2kWh Aeon battery (full specifications here) are landed and reaching customers, with a grid-scale 30kWh battery due to ship during 2020.

We asked Johns why the company is taking a punt on a technology that has so little awareness, and he nominated long life as its killer feature – Zenaji is offering the Aeon with a twenty year replacement warranty. Johns claims that guarantees customers will get a return on their investment without external factors such as government subsidy.

“As long as you treat the battery reasonably well, it really will last at least 20 years,” he said. “At three cycles a day, that’s 22,000 cycles.”

Johns said at the 20 year mark, the batteries will retain a minimum 80% of their capacity, and if a fault develops, it’s “not a declining warranty” (as is the case for lead acid batteries, for example).

And that’s just the warranty life: Johns believes the lithium titanate batteries should have a useful life of as much as 50 years.

Zenaji CEO and CTO with battery

Dawson Johns (right) and Charles van Dongen with the company’s slim Aeon battery

That, Johns said, should give the Aeon a lead in terms of return on investment other Li-ion batteries can’t match, in spite of its premium upfront price ($3,000 per 2 kWh battery module). This is because over the Aeon’s warranty lifetime a lead acid or conventional li-ion will have gone through at least one replacement cycle.

Inside The Zenaji Aeon Battery

For those who need it, here’s a quick primer on the well-known Li-ion battery: charged lithium atoms (ions) pass from the cathode (made from lithium cobalt oxide) through the electrolyte solution, to the anode (made from carbon).

In the chemistry Zenaji uses, the anode is made from lithium titanate nanocrystals, which have a much larger surface area than carbon anodes – 100 square metres per gram (m2/g) compared to a mere 3m2/g for carbon.

That huge surface area lets the charge-carrying ions pass into the anode in huge numbers, resulting in faster charge and discharge rates. CTO Charles van Dongen told us in an e-mail the lithium titanate battery can be typically be recharged in minutes rather than hours. Given that, the chemistry looks like a natural for EVs, but for one thing: conventional Li-ion beats them in energy density, and you need that to ease the owner’s range anxiety.

The chemistry has a safety advantage as well:

“The lack of carbon in the anode of the LTOs eliminates any overheating problems making the battery safer to use,” van Dongen told us.

Safety also gets a boost from the lithium titanate anode’s surface area – the current density per unit area is comparatively low, so the anode’s surface doesn’t heat up as much as a carbon anode.

Finally, van Dongen wrote,

“the major mode of failure in conventional Lithium Ion batteries is due to dendrite growth between the electrodes that eventually leads to internal micro short circuits. This process is completely absent in Lithium Titanate”.

Of course there are downsides, he said.

“The tradeoffs are much higher material cost and complexity compared with graphite, and the lower operating voltage (comparable to that of a lead acid cell) results in lower energy density.”

What kills a battery in a vehicular application isn’t so important in grid storage. Yes, you need to find a place for a larger physical package on a like-for-like basis, but the higher operating temperatures the Aeon chemistry can sustain – for example, they can cope with 55° Celsius, means in most parts of Australia the batteries could be installed underneath solar panels.

Easy Installation

Zenaji isn’t a cell manufacturer – the battery internals come from a Chinese manufacturer, with Zenaji concentrating on designing the battery management system and packaging. Johns noted delivering products with such long lifetime expectations has unexpected challenges, such as trying to find a circuit breaker likely to last that long.

Johns told us battery management is simpler, because discharge from 55.5V down to 42V is “a straight line, so you know how full it is”. That takes complexity out of the battery management system, and that in turn means “these are possibly the simplest batteries to install”, because “you don’t need complex communications”.

Rather than spending time on programming, “any competent electrician” can install the batteries, there’s no need for air conditioning — and the Aeon is a two-man lift onto a wall mount.

“We’re talking to a number of inverter companies to get a Zeniji setting, to make it easier to set up,” he added.

Zenaji’s next moves are to scale up manufacturing, and to bring its 30kWh grid-scale version to market. Fortunately, Johns is a technology manufacturing veteran, with a history stretching back decades. Old-timers in the IT sector may remember an Australian X-terminal vendor called Labtam, which was eventually sold to US company Tektronix.

Johns said ramping up manufacturing of the Aeon is a matter of funding, and is confident that it can be secured.

Zenaji is considering whether it’s possible to assemble the upcoming 30kWh grid-scale version in Australia. It will be packaged either in a large enclosure, for large household storage applications, or containers, for grid applications.

A local assembly plant:

“would largely depend on what level of government assistance we can get here, as opposed to other countries”.

About Richard Chirgwin

Joining the SolarQuotes blog team in 2019, Richard is a journalist with more than 30 years of experience covering a wide range of technology topics, including electronics, telecommunications, computing, science and solar. When not writing for us, he runs a solar-powered off-grid eco-resort in NSW’s blue mountains. Read Richard's full bio.


  1. Anticipated total cost?

    • Ronald Brakels says

      I have some information from Zenaji. Four batteries with a total of 7.7 usable kilowatt-hours of storage comes to $14,970. That’s $1,944 per usable kilowatt-hour. So the upfront cost is a lot, but if they last as long as claimed they should be good for Mad Max proofing your home.

      Note they may have since updated their prices.

      UPDATE: This price includes an inverter. I’m hoping to find out how much the inverter is.

      UPDATE UPDATE: The price is $12,000 for 4 batteries with 7.7 kilowatt-hours of usable storage. That’s $1,558 per usable kilowatt-hour.

  2. koen weijand says

    LTO batteries are the way to go. toshiba is marketing their SCiB cells as high rate and many cycles. at only 2.4V per cell the Lithium hardly wears out. just the price has to come down,but 20kcycles if charged softly makes up for the price easily.

  3. Chris Blair says

    We are replacing our old 3 phase 16kW air conditioner, and installing solar panels plus a battery. We would like to be able to use both the solar and the battery during a blackout.

    We can get a 16KW air conditioning unit in a single phase. We live in Sydney.

    Suggestions and comments are welcome

    • Ronald Brakels says

      Hi Chris

      It’s difficult to know what to suggest without knowing how much you can spend. If you don’t mind paying over $30,000 you could get a large solar system with a hybrid inverter, a moderate sized battery bank, and a small generator so you’ll never be caught short.

      A lower cost approach would to be make do with something like a single Powerwall 2, but you’d have to be careful with your electricity use, as it can only provide 5 kilowatts of power and an inefficient air conditioner with 16 kilowatts of cooling/heating ability can draw nearly 5 kilowatts of electrical power. It will also only hold a maximum of 13.5 kilowatt-hours of usable energy when new, so unless you always kept it nearly fully charged, it would be easy for it to run flat in a prolonged blackout.

      • Chris Blair says

        Thank you Ronald for very helpful advice.

        Having a small generator to top up during blackouts instead of a second Powerwall is a sensible option.

        Any suggestions, esp fuel type – natural gas or diesel.

        Any special issues connecting a backup generators to a solar system with blackout capabilities?

        A separate article on backup generators would, I think, be of interest to many readers.



        • Ronald Brakels says

          The best generator fuel will depend on your situation and what is available. It also depends on how often you think you’ll use it. Petrol can be stored for perhaps 18 months in a sealed container and diesel for up to a year. LPG can be stored almost indefinitely. With the right hybrid inverter and battery set up you can get away with a very small generator as it won’t have to meet your peak power draw during a blackout. One decision will be if you want to hardwire the generator in or you could leave it separate so if a friend or relative has a blackout when you don’t you could lend it out.

  4. Michael Oberhardt says

    Great news. I’m always following battery tech as it is something all the current offerings seem to always miss the mark in some way – including tesla with the internal invertor taking up system invertor capacity in QLF

  5. Bret Busby in Western Australia says

    The point with this battery, is notsomuch the initial capital cost for the battery (which I am not dismissing, as it IS an important factor in decision making), as the Levelised Cost per Warranted Kilowatt Hour, which I explained in a post, which has been subject to moderation, for a few days, now.

    I would be interested to see the details of the 30kWh battery, if and when it becomes available, and, what, if any, effect, cycles have, where the battery is only partially recharged.

  6. Have Zenaji got any data on the efficiency of their cells?

    • Charlie van Dongen says

      We rate it at 1C charge/ discharge at 25 degrees C to be around 96%. At lower C operation and higher temperatures it gets to around 98%

  7. Great!….. Now all I need is guarantee that I’LL be round ~ and willing to use archaic technology~ in 20 years……Anything less means the relatively HUGE price cannot be justified on any realistic benchmark.
    On ANY rational count the proven (and CHEAP agm-type LA battery) is by far the best option. I see they’re currently available @ between $1 and $2 per AH
    (which = up to about $150 per kWh of storage), and carry a warranty of 1 to 5 years. (some on a pro-rata basis).

  8. Charlie van Dongen says

    Hi, Charlie the CTO here. Just a small clarification. While you can install these batteries under the panel as temperature and our IP65 rating is fine, it is not our recommended method.

    The under panel concept was actually what gave us the idea of using Lithium Titanate originally as we were looking at an “all in one” unit modular unit that included the inverter/ charger. Ultimately we went for just the battery!!

  9. Bret Busby in Western Australia says

    The battery is warranted for operation at only 22 degrees centigrade. Loud Raspberry.

    • Ben Mathews says

      Bret, warranty document is available to show the “real warranted operation” which is contrary to this.

      Please contact me directly for any information you require.

      [email protected]

      • Bret Busby in Western Australia says

        I would reply, citing the source of my information, but the blog administrators are censoring out my postings.

      • Bret Busby in Western Australia says

        In the warranty document, as created by Dawson Johns and published on the Zenaji web site, from whence it was retrieved, with the heading

        Zenaji Australia Pty Ltd
        Product Warranty
        Effective Date: 29 October 2019
        Applies to: Zenaji 1.93kWh Aeon Battery


        It is important that you maintain your battery at normal room temperatures (22 degrees) or slightly below or
        the lifetime and cycle warranty will degrade and decline as per the below figures.

        which pretty clearly shows the batteries to be subject to the full cover of the warranty, only if operated for the full period of the warranty coverage,

        “at normal room temperatures (22 degrees) or slightly below”


  10. Ben Mathews says

    For all product enquiries please contact Ben – Australian Sales Manager @ Zenaji

    [email protected].

  11. Bret Busby in Western Australia says

    For the LCpWKWH (Levelised Cost per Warranted kiloWatt Hour) calculation,
    WC = 20 * 365 * 1 (using one cycle per day)
    = 7300
    PC * DoD = 1.93 (usable capacity)
    RE = 0.96
    DRoE = 0.905

    So the numerator is 7300 * 1.93 * 0.96 * 0.905
    = 12240.5 (rounded)

    LCpWKWH = 3000 / 12240.5
    = 0.2451 (rounded)
    = 24.51 cents per warranted kWh.

    And, with the purchase price cited above, of 3000 for a battery with 1.93kWh of usable capacity (from the Zenaji web page for the battery), that is 1554.40AUD per kWh of usable capacity.

    For 13.5kWh of usable capacity (to compare with the examples below), the purchase price would be (on a pro rata basis),
    13.5 * 1554.40 = 20984.40AUD.

    This compares with calculated values for the LCpWKWH, of
    24.46 cents for the DCS PV 13.5, which has a current price of 10750AUD for 13.5kWh usable capacity (796.30AUD per kWh usable capacity)
    24.34 cents for the BYD B-Box Pro 13.8, which has a price of 9600AUD for 13.8kWh usable capacity (price and data used for calculation, sourced from Solar Quotes battery comparison table) (695.65AUD per kWh usable capacity).

    Is this Zenaji thing economically feasible, and a good buy?

    Not from these figures.

    The above battery prices are for only purchase of each battery, and, do not include delivery and installation, or the cost of associated inverters, to the best of my knowledge.

    • Anyone can add a year to a warranty to make cost per warrantied kWh number drop, but that makes no difference to the financial benefit (or loss in most cases) actually realised by a homeowner.

      Financial cost/benefit analysis on that basis is pretty meaningless unless and until you factor in how a battery will be used in any given home (to assess capacity utilisation for instance) its performance characteristics (e.g. charge and discharge power limits and round trip efficiency) and the electricity tariffs which apply (import, TOU and export), both now and into the future (with all the increasing uncertainty involved the further into the future one looks).

      Which is why the installed cost per kWh of storage capacity is more useful in this respect. Then you can, based on your own tariff structures and expected capacity utilisation, assess what sort of return rate you are going to get from a battery today, and with reasonable certainty over the next handful of years. Beyond that is a crap shoot.

      That one battery might have a longer warranty over another is nice but in and of itself doesn’t mean it’s a financially more prudent or optimal choice.

  12. Charlie van Dongen says

    Hi Bret, from the actual warrantee………………………

    Temperature effects on cycles and length of time warranted.
    • -40 to -10 degrees Celsius. Cycles warranted decline from 22,000 cycles by 10 cycles per day that the batteries are used at these temperatures. The warranty on time is also reduced by 10 days for each day the batteries are cycled at these temperatures.
    • -10 to +5 degrees Celsius. Cycles warranted decline from 22,000 cycles by 5 cycles each day the batteries are used at these temperatures. The warranty on time is also reduced by 5 days for each day the batteries are cycled at these temperatures.
    • +5 to +35 degrees Celsius. Cycles are warranted at 22,000 cycles and 20 years.
    • +35 to +45 degrees Celsius. Cycles are warranted to decline from 22,000 cycles by 5 cycles each day the batteries are used at these temperatures. The warranty on time is also reduced by 5 days for each day the batteries are cycled at these temperatures.
    • +45 to +60 degrees Celsius. Cycles are warranted to decline from 22,000 cycles by 10 cycles each day the batteries are used at these temperatures. The warranty on time is also reduced by 10 days for each day the batteries are cycled at these temperatures.
    • Operating a battery in temperatures below -40 degrees Celsius or over +60 degrees Celsius will void your warranty.

  13. Chris Thaler says

    Now the icing on the cake would be an external insurance policy underwriting the warranty 100% in case the manufacturer/supplier disappears into the corporate ether during the warranty period.

  14. Hi,

    Sorry, a 20 year warranty? Really? Will the company (let alone the purchaser) still be in existence?

    How are they going to guarantee (;p) they’ll be able to honour it?

    Good luck to them though (both the purchasers & the company).


  15. It’s great we have another battery choice but is it really going to fly given the costs are still way too high for a domestic scenario? We need to be talking about $200/kWh to be making financial sense.

    Aside from the absurdity of a start up operation offering a 20 year warranty, the payback time on these batteries *for me* is 46.5years. A 7.7kWh battery saves me a whopping $258 per year. My solar PV system saves more than 10 times the money per year than adding this battery does.

    This is based on my own detailed modelling of 5-min energy flows when adding a simulated battery to the system of the specifications listed and with an installed price of $12,000.

  16. Anthony Helsby says

    will these batteries power the house and also continue to charge from the panels in case the grid goes down?

    • Ronald Brakels says

      That will all depend what type of inverter they are connected to. With the right hybrid inverter they will enable a home to operate entirely independently from the grid. This won’t be cheap to set up though.

  17. Anthony Helsby says

    In my mind it’s almost pointless in having a battery if you don’t get the benefits of UPS and able to have the batteries continue to charge off the panels during an outage. I reckon a couple of grand is offset by the savings in not having to purchase a generator which is unlikely to provide a UPS facility (unless you’re really well off)

    • > unlikely to provide a UPS facility (unless you’re really well off)

      Certainly not cheap to buy or run for a true UPS generator, but an auto-start 3kW generator can be up and running in ~10 seconds if you use a relay that closes when the mains go down to trigger auto-start. Cost ~$1000 for 10+ hours run time on a tank of fuel.
      Manual plugging in fridges etc required unless you want to spend a bit more for an auto-changeover switch.

      Sadly, yes it is environmentally unsound FF burning, but you have to draw the line somewhere when batteries are so expensive, and after 20 years you are unlikely to have spent anywhere near the cost of the batteries under discussion here.

  18. $6,000 for 4kW that will last 20 years? $6K over 20 years is 54c a day. Okay, I’m “in”! When solarquotes,com.au keeps telling me batteries have poor ROI?

    Well as I see it 4KW is more than I would use overnight.

    And during the day I hear my 18c rebate for each kW I sell to the grid is going to return even less as there is simply too much daytime solar – I already have 6.6kW of panels and use little of the energy it creates each day.

    So how can batteries be a bad ROI??

    • Ronald Brakels says

      Finn has a Powerwall 2 it saves him an average of less than $1 a day. If it lasts 15 years it will never pay for itself at its full price or its subsidized SA price. That’s the case even if you value its backup capability at a couple of grand.

      • Bret Busby in Western Australia says

        Ah, but the Tesla Powerwall 2, is not a comparatively good buy, or, a good example to use for economical feasibility of ESS batteries for PV systems.

        My calculations show, for batteries and their Levelised Cost per Warranted KiloWatt Hour,
        Tesla Powerwall 2 – 30.5 cents
        LG Chem RESU 10 – 32.76 cents
        (the full size, 13.5 kWh RESU 13.5 was missing from the SQ battery comparison table)
        BYD B-Box Pro 13.8 – 24.34 cents
        DCS PV 13.5 – 24.46 cents
        and, for the Zenaji battery, as mentioned above, 24.51 cents.

        So, the Tesla Powerwall 2 battery, is one of the more expensive battery options, and, perhaps, not a good example to use as a reference for economic feasibility of ESS batteries for PV systems.

        As I have stated elsewhere, my calculated values for the Levelised Cost per Warranted KiloWatt Hour, for the batteries, relate only to the purchase price of the batteries, and, do not take into account, delivery and installation, or the price of associated required inverters.

  19. Chris Blair says

    Autostart UPS generator ?

    This topic has generated (?) an excellent and very knowledgeable series of contributors.

    May I suggest another topic devoted to backup generators, the role of UPS, and how a generator can be integrated into a solar + battery configuration.

    Based on the response to this thread, it is likely to be very popular.

  20. See this report (11th Nov 2019) by iTWire:
    Senec apparently is going to provide a 20-year warranty also.

    How does this battery compare with Senaji’s?

  21. do these batteries work with MPP Solar inverters?

  22. Thanks again and can I install it myself—–it appears it’s only a couple of wire to hookup to the mpp solar inverter and a simple install.

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