Dyness Powerbox Battery: A First Look At Its Specifications & Warranty

There’s a new battery contender in town – the Dyness Powerbox. And if you live in SA it’s eligible for South Australia’s hefty home battery subsidy. Finn tells me it looks a lot like a Tesla Powerwall 2, but I don’t see it myself and I’m going to defend the Powerbox by pointing out all the ways it doesn’t resemble a Powerwall.  For one thing, it’s got rounded corners.

Also, unlike the Powerwall 2, the Dyness Powerbox¹ doesn’t contain a battery inverter and so requires a compatible hybrid inverter to work.  This contender is just a container that holds up to 4 battery modules.  Each module has:

• 2.4 kilowatt-hours nominal capacity
• 2.16 kilowatt-hours usable capacity
• 1.2 kilowatts continuous power output
• $1,200 subsidy in South Australia

When 4 modules have their powers combined into a fully loaded Dyness quad module Powerbox, it will have:

• 9.6 kilowatt-hours nominal capacity
• 8.64 kilowatt-hours usable capacity
• 4.8 kilowatts continuous power output
• $4,800 subsidy in South Australia²

The battery’s chemistry is lithium iron phosphate (LiFePO₄) which is the lithium chemistry most able to handle misuse.

Its operating temperature is from 0 to 50ºC.  This is a good for a lithium battery and suitable for most of Australia.

Its warranty promises modules will retain 70% of their original capacity until 10 years have passed or they have provided 6,700 kilowatt-hours.  Whichever comes first.  This means a household would have to use an average 0.76 full cycles³ or less per day for the batteries to retain the 70% capacity warranty for 10 years.

If you are in in South Australia and want a subsidised Dyness Powerbox, they can only be obtained from one provider at the moment — Target Solar.  If you’re not in SA another provider I know of is Sealed Performance Batteries or SPB for short.

Update 18 Nov 2019:  Another supplier of the Dyness Powerbox is Solar Energy Warehouse. 

Tech Specs

Here are technical specifications for the Dyness Powerbox lifted straight from its brochure:

I’ll go into some of these numbers in more detail and explain why — if you care about keeping your warranty — many of them are irrelevant.

Storage Capacity

Each module has a nominal storage capacity of 2.4 kilowatt-hours, but the warranty limits the maximum depth of discharge to 90%.  This makes their usable storage capacity 2.16 kilowatt-hours when new.  This comes to to a total of 8.64 kilowatt hours when a Powerbox is maxed out with 4 modules.

If more energy storage is needed, multiple Powerboxes can be used.  While Dyness says there is no limit, I think the average inverter will have problems handling a limitless number of Powerboxes.

Power Output

Energy stored is given in kilowatt-hours but power is kilowatts.  If you need to check out the difference between the two, Finn bangs on about energy vs. power here.

The maximum power output for each module given in the tech specs is 2.4 kilowatts.  However the warranty states:

This means, in normal use, the power the module can supply or be charged with is 1.2 kilowatts.  The maximum continuous power output for a 4 module Powerbox will be 4.8 kilowatts.

Indoors Or Outdoor Installation

The Powerbox has an Ingress Protection (IP) rating of 65:

This means it can be located out in the rain without problem.  But flooding is a problem, so keep that in mind if it’s on the cards.  Because heat is not good for batteries I definitely recommend locating it out of sunlight.  According the warranty they cannot be exposed to temperatures over 60 degrees.  Fire safety is also a consideration whether it’s located indoors, outdoors, or pretty much anywhere in Australia.

Dimensions And Weight

I’ve mentioned that some people — or some person — think the Powerbox is attempting to look like a Tesla Powerwall, but no one can deny from the front it looks considerably smaller:

But because the Powerbox is thicker, the volume of the Powerwall 2 is only 25% more:

• Dyness Powerbox volume = 108 litres
• Tesla Powerwall 2 volume = 135 litres

Because the Powerwall 2 has more storage capacity (13.5 kilowatt-hours when new) than a maxed out Powerbox, it wins on litres of volume per kilowatt-hour of usable capacity:

• 4 module Dyness Powerbox volume per usable kilowatt-hour = 12.5 litres
• Tesla Powerwall 2 volume per usable kilowatt-hour = 10 litres

As the Powerwall 2 contains a battery inverter and an active cooling system while the Powerbox is just batteries, the lithium iron phosphate battery cells inside obviously take up more space than the NMC (Nickel Manganese Cobalt) cells used by Tesla’s Powerwall 2.

While the Powerbox’s smaller size is not impressive given it’s lower capacity and functionality, it still counts as a difference in appearance from the Powerwall 2.  I’m even going to make a list of all the ways its appearance is different:

“Oh Dyness Powerbox, how art thou different from a Powerwall 2?  Let me count the ways…”

• Smaller
• Fatter
• Rounded corners
• Six visible holes for bolts or whatever type of fasteners it uses

See, Finn?  They’re nothing alike!

Compatible Inverters

Dyness provides a long list of inverters they say are compatible with the Powerbox and list them in an order that’s not at all alphabetical:

• Goodwe — China
• Victron — Netherlands
• Solis — China
• Imeon — France
• Luxpower — China
• Growatt — China
• GMDE — China
• Sofar — China
• Voltronic — China
• Ningbo Deye — China

If your response is,

“I’ve never heard of some of those inverters!”

I would say,

“Join the club!”

I’ve put the location of their headquarters or where I know their manufacturing is done next to the names.  As you can see, a whole lot of inverters are being made in China.

Dyness says more compatible inverters will be announced in the future.  I’ve noticed battery manufacturers always say this, but it doesn’t always happen.

Backup Depends On Inverter

What kind of backup power, if any, the Powerbox will be able to provide depends on the inverter it’s connected to.  Generally speaking, it’s possible to get almost instantaneous changeover to battery power in a blackout as well as the ability to charge the Powerbox from solar panels when the grid is down.   With a suitable inverter they can be used entirely off-grid.

Operating Temperature

In its tech specs the operating temperature range is given as -20 to 50 degrees, which is excellent.  Unfortunately, that’s not what the warranty allows.  It states:

While this will no doubt disappoint anyone planning to use it in the (not very) Snowy Mountains or the Australian Antarctic Territory, it’s still a good operating range for Australia.  Because it says “operating environment” I am going to assume it means air temperature.  If it’s battery temperature that’s very different as they heat up from energy losses when charging and discharging.  The good news is other lithium iron phosphate batteries are able to operate in air temperatures of up to 50 degrees, so it’s likely the Powerbox modules can do the same.

Battery Efficiency May Be 95%

The tech specs don’t give the battery round trip efficiency, but information I’ve acquired puts it at 95%.  That’s not bad, but it’s only for charging and discharging the battery and doesn’t include inverter or other losses.

Warranty

The tech specs say the battery can be cycled 6,000 times, but looking at the small print…

…reveals this only is when the battery is treated like a little baby.  It has to be:

• Kept at a constant 25 degrees
• Charged and discharged at a mild 480 watts per module
• Discharged to a depth of only 80%

But if the battery is treated this gently, the warranty doesn’t care and won’t cover that many cycles.  What it will cover is 3,650 full cycles or 10 years.  Whichever comes first.  Fortunately, for most homes, 10 years should come first.

Using the average of 365.25 days in a year, the maximum amount of stored energy that can be provided while remaining in warranty is:

• Per module:  8,766 kilowatt-hours
• For a 4 module Powerbox:  35,064 kilowatt-hours

Because most households fully cycle their batteries less than once per day and because the battery capacity will deteriorate over time, this amount is unlikely to be reached inside of 10 years.⁴

Warranted Remaining Capacity — There’s A Trick To It

Like almost every home and business solar battery,⁵ its warranty promises it will maintain a specific percentage of its original capacity.  But the Dyness Powerbox does it in a weird and, I think, unfortunate way.

The warranty promises the battery will retain at least 70% of its original capacity until 10 years pass or it has provided 6,700 kilowatt-hours.  This is only three quarters of the 8,766 kilowatt-hours of energy output its warranty covers.

This means for the warranty to still cover it having 70% of its original capacity for the full ten years the average amount of stored energy that can be used each day would be only:

• 1 module:  1.83 kilowatt-hours
• 4 modules:  7.34 kilowatt-hours

That is an average of 0.76 full cycles per day.  Many households could reach this point before the 10 year warranty maximum is reached and so have a period where the battery modules would still be under warranty, but with no promised minimum amount for remaining battery capacity.

This is an odd warranty.  I presume they are not confident the batteries will still be at 70% of their original capacity after 10 years but didn’t want to have either a minimum promised capacity of under 70% or warranty of less than 10 years, so Dyness went with this weird solution.  I don’t like it as it makes the warranty harder to understand and makes it more difficult to compare with other battery warranties.  I hope they will improve it, or at least make it simpler.

I suppose many households would still use an average of less than 0.76 full cycles per day and so the Powerbox will end up warranted to have at least 70% of its original capacity for 10 years.  But if you plan to use your battery at high capacity, watch out for this.

Dyness Doesn’t Understand Temperature

Lithium iron phosphate is the most stable lithium battery chemistry, but that alone is not enough to make it safe.  If it’s not part of a well designed system then any lithium battery is dangerous and all are capable of catching on fire, venting flames, spewing toxic gases, and — if tightly confined as battery cells usually are — exploding.  None-the-less, Dyness makes a big deal of lithium iron phosphate (LiFePO4) batteries’ safety:

Wait, what was that?  Say that middle bit again!

No it’s not!  It’s not 100% higher!  Dyness even provide a graph that contradicts this:

This is a graph of the Temperature Range of Decomposition, which is a fancy way of saying “at these temperatures the shit starts to hit the fan and the fan is made of explosions”.

If we look at the lower ends of the bars on the graph, the temperature at which the blue bar of the LMO battery starts to get explody is almost half the degrees Celsius figure of the green lithium iron phosphate (LFP) bar, but that is not a 100% higher temperature.

The freezing point of water was chosen as zero for Anders Celsius’s temperature scale because that’s convenient for humans,⁶ not because temperature starts at zero Celsius.  It starts at absolute zero which is -273.15 degrees Celsius.⁷  This is zero on the Kelvin scale which is something Lord Kelvin came up with in between inventing the Kelvinator and working out the first two laws of thermodynamics.

I’ll fix Dyness’s graph for them so temperature starts where it should:

That’s better.  Now we can see that lithium iron phosphate batteries start to get explody when their temperature is about 46% higher than the next most stable battery chemistry, not 100%.

Dyness — The Company

Dyness is located in Yangzhou City in Jiangsu Province in China.  Yangzhou City is famous for its Slender West Lake and for not quite being in the top 29 most polluted cities in China.

I haven’t found any evidence of Dyness existing before 2017.  Although it’s a young company I’m not going to hold that against them and I’m happy to wait and see what they can do.  It’s only if companies screw up that I mock them relentlessly and mercilessly.

But we can be sure their Research & Development department has some real smarts behind it, as this passage from their website demonstrates:

Thank god they didn’t have to share a laboratory with one of those abnormal universities.  I’ve seen enough monster movies to know that could have been disastrous.

The Dyness website also tells us how great their Powerbox is:

If they can do that and combine it with a better warranty, they should be onto a winner.  After all, who doesn’t like top class quality at an affordable price?  It’s amazing how few companies think of providing both of these things at the same time.  It’s almost as if they’re not really trying to succeed in business.

No Dyness Australian Office

Dyness does not have an office in Australia.  This means its importer has responsibility for the manufacturer’s warranty while the business you purchased it from still has all its obligations under Australian consumer law.

But Australia is important to Dyness because on their world map Australia has 4 out of 21 dots:

That means we’re in possession of 19% of Dyness’s map dots and that’s got to count for something.  Unless it doesn’t.

Availability And Price

If you’re in South Australia and want a Dyness Powerbox, the only place you can get one and receive the state’s subsidy at this time is Target Solar.  The subsidy is $1,200 per module or $4,800 for a Powerbox stuffed to the brim with 4 of them, so chances are you’re not going to want to miss out on it.

If you’re not after the SA subsidy, then Sealed Performance Batteries (SPB) is another provider of the Powerbox.  Based on information they gave, my estimate of the price of a Dyness Powerbox with 4 battery modules and 8.64 usable kilowatt-hours of storage is around $8,900.  This is before installation and doesn’t include a hybrid inverter.

SPB told me they have been using a 5 kilowatt Luxpower inverter with the Dyness Powerbox.  This inverter is new in Australia and I was told it can provide full backup and accept up to 8 kilowatts of solar panel capacity.  This is useful for people who are getting both solar and a battery installed at the same time, as STCs — usually referred to as the “solar rebate” — can be claimed for the full 8 kilowatts when a battery is being installed as well, rather than the usual maximum of 6.66 kilowatts for a 5 kilowatt inverter.  My price estimate for a this Luxpower hybrid inverter is around $2,600.  Again, this is before installation.

The people who will get the most bang for their buck from a Dyness Powerbox will be those installing a new solar power system with 8 kilowatts of panels.

Wallet Warning

In case you didn’t know, I’ll mention home batteries won’t pay for themselves at the moment unless there are special circumstances.  This is generally the case even with South Australia’s big fat subsidy.  So if your motivation is to save money, be very cautious and maybe keep an eye out for useful offers from Virtual Power Plants.

But if you’re not worried about losing money, then can I borrow some?  I only need enough to get me through Christmas and possibly purchase a small castle.