LG Chem Resu 6.4Ex vs Tesla Powerwall

LG resu 6.4ex and a powerwall

How does the LG Resu compare to the Tesla Powerwall?

If you are looking at a 6.4kWh Lithium-Ion battery for use in Australia right now, you are probably tossing up between a LG Chem Resu 6.4Ex and the Tesla Powerwall.

To help you decide which one is for you – here is a side by side comparison, and some commentary on their warranties below.

LG Chem Resu 6.4EX
$7,500
6.4kWh nominal storage
5.1kWh warranted
-
drops to 3.8kWh after 7 years
3.6kW steady, 4.6kW peak
single or 3 phase
no inverter included
10 year warranty
19.2MWh warranted throughput
warranty void at 50ºC ambient
Tesla Powerwall
$8,000
6.4 kWh nominal storage
5.4kWh warranted
drops to 4.6kWh after 2 years
drops to 3.8kWh after 5 years
3.3 kW, 5kW peak
single or 3 phase
no inverter included
10 year Warranty
18MWh warranted throughput
warranty void if avg temp > 30ºC

The most important numbers to consider when buying a battery, are the ones that the manufacturer will actually warrant. I’ve read both warranty documents in detail and here’s how they compare in terms of battery performance over 10 years:

Tesla Powerwall

Despite the 6.4kWh nominal storage capacity, the Tesla is only warranted to give:

  • 5.4kWh over the first 2 years
  • 4.6kWh for the next 2 years
  • 3.8kWh for the final 5 years of the warranty

This gives a total of 16,000kWh of warranted energy output over the warranty period cycled once per day, or 18,000kWh if you cycle it more than once per day.

The low kWh for the final 5 years of the warranty is a definite disadvantage, and will cause disappointment for people who were hoping to cover 5-6kWh of energy consumption overnight for the life of the battery.

Here’s what the warranty looks like:

tesla powerwall warranty conditions graph

Warranted energy storage for the Tesla Powerwall.

Internet connection requirements

The warranty will be voided after 48 months if you don’t connect the Powerwall to the internet and register it within 3 months after the installation. Also your internet must not be down for more than 45 days following registration or the warranty is voided.

Operating Temperature

The warranty document does not explicitly give a temperature range for operation or storage – but it does say the battery must be used as per the user manual. The user manual says “The average ambient temperature over the system’s life should be 30°C or less”.  Kudos to Telsa for not voiding the warranty if the battery is occasionally subject to some of the extreme temperatures we get here in Australia.

LG Chem Resu 6.6 EX

The LG Chem battery is warranted to retain:

  • “at least 80% of Nominal Energy 6.4kWh for 7 years”
  • “and at least 60% of Nominal Energy 6.4kWh [for the following 3 years]”

This gives a total warranted throughput of 17,000kWh cycled once per day or 19,200 kWh if you cycle it more than once per day.

The warranty also stipulates that you should not discharge more than 1920kWh per year. If you do, then the warranted kWh is reduced on a sliding scale. I won’t go into the details here – you can read them in the warranty document. I suspect that the details of this will be irrelevant to most people as I’m guessing the Battery Management System (BMS) will be programmed to never breach the 1920kWh per year limit by default.

In the chart below, I’ve worked out the max number of cycles you can perform to stay under the warranted kWh as a % of nominal energy, and also keep under the annual kWh limit (1920kWh per year).

As you can see you certainly get the initially warranted energy storage, for longer, compared to the Powerwall.

LG Chem Resu 6.4EX warranty chart

LG Chem Resu 6.4EX warranted energy storage

Warranted Temperature Range

The battery warranty is voided if the battery operates below 0ºC or over 40ºC. I believe the battery has a temperature cut out switch that makes this impossible – unless you override the default software.

The warranty is voided if the battery is exposed to a temperature over 50ºC. So don’t keep it in an uninsulated garage or shed.

Conclusion

Both batteries are about the same price, give or take $500. Both warrant a similar amount of energy give or take 1,200kWh over 10 years.

The LG’s warranted energy is more consistent than the Powerwall’s, which will make it easier to design into your home, and predict savings.

The LG is definitely easier to install mechanically.

The LG is sold by the major wholesalers, so any installer can get hold of it. The Tesla is only available from a select few installers.

The LG can be expanded by 3.6kWh at a time. The Powerwall can be expanded by 6.4kWh at a time.

The Powerwall is more tolerant of extreme Aussie temperatures. You have to be careful not to expose the LG to more than 50ºC, and be aware that it will cut out automatically at 40ºC.

The total installed price of the LG will be lower because it is compatible with cheaper hybrid inverters. The Powerwall only works with Solar Edge on single phase and Fronius on 3 phase. This will change when the ~$1,500 SMA Sunny Boy Storage battery inverter is released.

My personal choice would be the LG. I value the more consistent, warranted kWh. It is more flexible in terms of inverter choice, installer choice, future expansion and installation location. Fully installed, it works out a couple of thousand dollars cheaper. And I have a well insulated garage, so I’m confident it won’t get too hot.

But if you are not confident that you can keep the battery under 40ºC then the Powerwall looks like a better choice.

And don’t forget all the other batteries that are out there which you can compare with our comprehensive battery storage comparison table.

About Finn Peacock

I'm a Chartered Electrical Engineer, Solar and Energy Efficiency nut, dad, and founder of SolarQuotes.com.au. My last "real job" was working for the CSIRO in their renewable energy division.

Comments

  1. At these prices none of them is compelling particularly when you look at that drop off figure.
    To put it in perspective I have 6.3 KW on my roof running through a 5.3KW inverter.
    Just checked my electricity account and I am importing around 10KW a day and another 8KW on hot water tariff. My system can produce up to 32kWh per day and of that I am exporting 18 to 22kWh a day.
    So at 6.3KW it is still short and then you have the drop off over 5 years.
    Not a compelling argument to do anything for a while .
    I have said it before.
    Unless these prices drop to around $3,000 and can store 11kWh its a no go and a waste of money and I am a 3 person household.

    • Hi Eric,

      Agreed, battery prices have to halve to become compelling for the majority of Aussie households.

      Finn

      • FIT dropped so it is now prob is now its 6c FIT and e.g. buy during peak which is 7am til 11pm and from 7-9am and 6-11pm solar not working so you getting it off the grid at peak times and I’m charged 31c so 10kw to get back during no solar times I’m paying 31c – FIT of 6c so i get small discount, rather put into a battery and use the extra

  2. John Harrison says:

    Better off waiting for the Aussie Z Cell Battery coming out Mid Year 10kW can be recycled Every day ..!!

  3. The proposed ‘Sunny Boy Storage Inverter 2.5’ for the Powerwall, has a maximum AC output of 2.5kW. DC battery input is limited to 2.65kW.
    There is no PV input. Appears to be a ‘back-up’ inverter.

  4. Warranties are open to interpretation, but LG’s new Lithium Polymer cell, is more likely to last longer than 18650 cell forced into unintended use. Calender life is important when considering 10 to 20 years’ use, but can be undermined if the effects of accumulated energy dominate. If the lower accumulated energy guidline is followed 80% at 10 years, and 60% at 20 years are within the warranty.

    LG’s warranty is specified according to accumulated energy.
    The first is;
    “If 0%<Use Rate <10%, then the warranted usable energy will be reduced by Use Rate ×0.3"
    Where Use Rate is 1920kwh/year. The above still applies if the total accumulated energy 10% greater. For that range, annual capaciity loss is calculated as 4.2% x 0.3 = 1.26%, or 98.74% retention.

    To be safe, assume 1920kWh/year.
    After 2 years, retention is .9874^2 = .9749 or ~ 97.5%, for 3.8MWh accumulated energy.
    At 2 years, the Powerwall warranities 4MWh, and 85% capacity.

    The difference is that for LG, ~4MWh is much less than could be accumulated at 2 years, if cycled more often, though at the expense of increasing capacity loss, whereas for Tesla, 4MWh is the most that can be accumulated, while retaining only 85% capacity at 2 years. When a battery shows such marked decline from the start, it is operating at the limit of performance.

  5. Good article, thanks Finn.

    According to your own battery storage comparison table the LG looks like a much better deal at 0.43c/kWh versus the Powerwall at 0.50c/kWh. That’s a 14% better deal BEFORE you factor in the inverter cost which, as you point out, is likely to be less with the LG.

    I also find it interesting to note that the best deal for battery storage currently available in Australia is our very own Redflow Z-cell. For larger systems this looks like the way to go. Perhaps an article comparing it to both the LG and Powerwall?

  6. I’m keen to hear more about the Z cell as it is Aussie built, keeping more of us employed,, low toxicity and recyclable .
    Now question on an open forum to all, ( at the very possible chance of showing my ignorance, but do we need a change-over switch and or ATS when going from running on batteries to going back to mains?

    Be nice,,, I’m a diesel fitter

  7. Hi Guys.

    I’m an owner/builder on a rural block and I’m looking for advice on the most sensible way to go in setting up an off the grid system.
    I live in Western Australia, 1hr north east of Perth with a north facing block.
    At present my wife and I are living in a shed using 12v solar power for lighting and TV and an inverter to run our fridge, which is working very well, though this system is not what I’ll be requiring when the house is built
    Do I go with Lithium batteries and worry about temperature issues as we have had 45 degree days during summer, or do I look at the liquid flow batteries, as either way it is going to be the same price if not cheaper than having the power company connect power to my block.

    • Ronald Brakels says:

      Hi Robbo, that is a tough question, as what will suit you best will depend on a number of factors. But you may be okay with a system that can operate at a maximum ambient temperature of 45 degrees provided it is well positioned out of direct sunlight and you have a generator to provide power if it shuts down due to extreme temperatures. But if you check out our battery comparison table:

      https://www.solarquotes.com.au/battery-storage/comparison-table/

      You will see there are lithium-ion batteries with operating temperatures of up to 65 degrees. But the ZCell flow battery could still be a good choice for reasons other than operating temperature.

  8. Hi Finn,
    I was wondering if you knew how many cycles the LG provides at various rates of DOD? I read somewhere that it is 6000 at 100% but that doesn’t seem right. If you could answer this and do a comparison with Lead Nanocarbon that would be interesting. Cheers

    • Ronald Brakels says:

      Hi Byron, Ronald here. The new RESU produced by LG Chem have a depth of discharge of around 90% and their warranty covers just under 2,500 kilowatt-hours of stored energy per kilowatt-hour of nominal capacity. That comes to around 2,700 cycles if deterioration in battery capacity isn’t taken into account. I wrote about them here:

      https://www.solarquotes.com.au/blog/new-lg-chem-resu-batteries-smaller-powerful-cheaper-powerwall/

      Comparing lithium batteries to lead-acids is very difficult because they are very different things. It’s not really possible without making some major assumptions about how the batteries are going to be used and not everyone is going to agree with those assumptions.

      But if you have a link to some concise information on the batteries you are interested in maybe I can do a quick and dirty comparison, or at least give an opinion.

  9. Peter Kesby says:

    Thank you Finn for a really informative website. Have already recommended it to friends considering solar.

    Your comments re payback on batteries at the moment is particularly helpful. Was about to spend but will certainly now wait awhile

  10. Peter Truscott says:

    Hi Guys,

    We live in the Hunter Valley on a small farm and have a stand alone solar system, which has served us well over the 7 years since we installed it. Now, our batteries are dying and we need to replace them. We’s like to explore using one of the new batteries such as the LG Chem units rather than just replace our current batteries with the same thing. Below is a rundown on our system:

    STAND ALONE – OFF GRID SOLAR POWER GENERATION SYSTEM

    Located at: Hunter Valley NSW
    Elevation: 425 M
    System Installed: February 2010
    Set-up: The 3 arrays are mounted on steel posts in a paddock about 30m from the house. DC power is underground to a dedicated shed near to the arrays which houses all equipment. AC power to the house and outbuildings is underground. All systems meet normal electrical standards.
    Solar Panels: 18 x ET 170 Watt set up in 3 arrays of 6 on actuated frame trackers.
    Inverter/Charger: Outback 3,000 Watt 48 Volt Model VFX3048E Note: Installation Manual and Programming Manual available
    Advanced Solar Charge Controller: Plasmatronics PL60 Note: Manual available
    Remote Monitor: Plasmatronics PLM installed in the house
    System Controller and Display: Outback Mate
    Batteries: 24 x B.NPG1000-2 (2V 1000Ah)
    Generator: Gentech Honda powered Remote Start Generator 8.0KVA
    Automatic Generator Controller: SmartgenHGM1780 V1.2
    Generator Battery Charger: Ozcharge Model OC121.5 trickle charger

    Current situation: The system works well except that the batteries are no longer efficient after about 8 years and they need to be replaced. This results in our generator running for approx 2 hours per day.

    Objective: Rather than replace the current batteries with the same units, we wish to investigate the potential of using a newer technology battery such as the LG Chem battery. We would also like to increase the battery capacity to provide more DC power storage, thereby relying less on our generator in times of low solar power generation due to long cloudy periods. The LG Chem Resu 6.4Ex sounds like it could work for us but we need to be sure of compatibility with our current equipment.

    Can you comment and make any suggestions please? I’d be happy to supply any further information you may need if I can find it in the manuals!

    • Ronald Brakels says:

      There are a wide range of non-lead-acid batteries now available, as our battery comparison table shows:

      https://www.solarquotes.com.au/battery-storage/comparison-table/

      One thing you could consider is increasing your PV capacity, as that can reduce the amount of battery storage required and reduce wear and tear on the batteries during the day. While it is possible to add PV to your existing system and get STCs for the first 940 watts added, any new panels added to the existing setup would be held back to the output of the old ones. (I assume, because of its age, your current inverter can only has one MTTP and so can’t handle two independent strings of panels.)

      The LG Chem RESUs are (mostly) 48 volt, as is your inverter charger, but your system is so old it probably can’t handle lithium batteries. So if you want lithium batteries, you’ll probably want to get a new multimode (hybrid) inverter. And if you get a new inverter, then it’s likely to make sense to expand your PV capacity to reduce the amount of battery storage you’ll need. Modern inverters can almost all handle two separate strings of panels so your current panels could be one string while new capacity can be a second string.

  11. Sheila Singh says:

    Hi, My electricity bills average around $450 quarterly, Despite having 20 solar panels on the roof. I have a ‘Solis 5K – 2G’ Inverter (from manufacturer: Ningbo Ginlong Technologies Co.Ltd). The solar installation was arranged by AGL Electricity Co. Unfortunately, my electricity usage in mainly in the evening due to all three of us working during day. I have been suggested to buy battery. I do not know much about this, would you be able to give me some suggestions. I was also told my Inverter in not compatible to support any battery. When I contacted AGL Solar, I was told certain types of batteries are compatible with the Inverter I have. I have rung different companies, got more confused with their questions and explanations. I am on 8c buyback with AGL, this is no help as I believe I am using the power from grid in the evenings. Could you please help tell me which would be a suitable battery in my case. Thank you. Sheila.

    • Ronald Brakels says:

      Hello Sheila.

      I am afraid that no battery will pay for itself at the moment. They have to come down further in price before that happens.

      The good news is feed-in tariffs increased for most Australians at the beginning of this month. I don’t know where you are, but in NSW AGL now offers 11.1 cents per kilowatt-hour. This means you will be paid more for the the electricity your solar system produces during the day and sends into the grid. Other retailers are offering even higher feed-in tariffs, but it is important to check they aren’t giving with one hand and taking with the other by charging more elsewhere.

      So I would check that your current retailer is giving a good feed-in tariff, and I would see if there were any better options available from other retailers. You can use our electricity plan comparison tool to see what’s available:

      https://www.solarquotes.com.au/energy/

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