EV Battery Packs Have It Easy Compared To Home Batteries
It has been two weeks since I laid down the heavy news that out of the 26 home batteries given a whirl by the Canberra Battery Test Centre, only two worked as they should without suffering a fault or excessive capacity deterioration. This sad news has caused some people to wonder if electric car battery packs will have similar poor performance.
Fortunately, on this topic, I’m the bearer of good tidings. I’m hauling so many high-quality tidings my back hurts.
The best tiding I have is:
- EV battery packs have it easy compared to home batteries. In normal use, they’ll be fully cycled far less often. This will help them to — mostly — go the distance their warranty promises and then some.
This chart illustrates the difference (you’ll have to read on to see my working):
I also have another tiding that isn’t exactly good, but it does improve the odds of EV battery packs having fewer problems:
- It’s harder for companies to get away with supplying unreliable EV battery packs without ruining their reputation compared to home batteries.
I’ll explain further below, so read on if you want to learn why electric car battery packs should mostly survive well beyond the end of their warranties and provide years of additional driving. If you’d like to read the Canberra Battery Test Centre article that caused this consternation, you can do that here.
Home Batteries Work Far Harder
EV batteries aren’t expected to supply anywhere near as much energy, per kilowatt-hour of usable storage, as home batteries. Their warranties make this clear. Fortunately, some companies sell electric cars and home battery systems, making the comparison easy. Two that operate in Australia are…
- BYD — A Chinese company that named itself after this combination of letters simply because they hadn’t been taken yet, but later decided it meant “Build Your Dreams”.
- Tesla — A US company founded by Martin Eberhard and later, in his dreams, by Elon Musk.
I’ll focus mainly on Tesla. While both companies have sold many home batteries here, Tesla has sold a lot more electric cars, and I have better information on them. But I will compare the warranties of BYD’s home batteries and their Atto 3 EV, which should now be available in Australia.
Tesla Powerwall 2 Warranty
The Tesla Powerwall 2 warranty says it will last for 10 years when it’s exclusively used for home use. If put to any other additional purpose, such as being part of a Virtual Power Plant (VPP), the warranty is for 10 years or until it supplies 37,800 kilowatt-hours of stored energy. Whichever comes first. In either situation, the warranty promises it will retain at least 70% of its original capacity by its end.
When a new and fully charged Powerwall 2 is discharged of all usable energy, it can supply 13.5 kilowatt-hours. If a battery is fully charged and then fully discharged1, that is called one full cycle. I’m going to use this term to refer to the maximum amount of energy a home battery or EV battery pack can normally provide when new. Batteries slowly decline in capacity with use, but I’m not taking this into account when I talk about full cycles.
For a Powerwall 2 to supply the 37,800 kilowatt-hours its warranty allows when not used exclusively for home use, it will need to be fully cycled 2,800 times. This is far more than the number of full cycles Tesla’s EV battery pack warranties cover.
Tesla Model 3 EV Warranty
Going by sales, the most popular EV in the world2 is the Tesla Model 3 Standard Range Plus — or Model 3 Rear Wheel Drive, as it’s called now. It has a battery pack of around 60 kilowatt-hours capacity, with 57.5 kilowatt-hours of usable storage. Its warranty lasts for 8 years or 160,000 km — whichever comes first. Like the Powerwall 2 warranty, it also promises it will retain at least 70% of its original capacity.
To work out how many full cycles 160,000 km represents, we’ll need to know the average amount of energy it consumes per km. I know from fun earned experience that Tesla’s figures for range can’t be trusted3, but the EV Database says it gets around 7.75 km per kilowatt-hour in mild weather. Using this figure means the battery pack warranty only covers around 359 full cycles before it hits its km limit. That’s only 13% as many as the Powerwall 2 warranty allows.
Climate Control & Vampire Drain
There are a couple of reasons to expect actual energy use per km driven to be higher than the EV Database figure I used. These are:
- Vehicle cabin climate control, and…
- Vampire drain
Climate Control
Australians are a pretty soft bunch. If you burn down their house, they complain bitterly. If their local cafe serves them a nice bowl of broken glass and rusty nails, they ask to see the manager. For this reason, I expect electric cars here will use a considerable amount of heating in winter and a lot of air conditioning in summer.
Unfortunately, the EV Database is European and doesn’t give figures for air conditioner consumption. This is despite the fact I’d expect Europeans to be using a lot of air conditioning at the moment, considering the River Loire has all but dried up.
Vampire Drain
Vampire drain occurs when the car isn’t in use, either because it’s thinking about stuff, updating software, or simply monitoring the battery. In some situations the EV may heat or cool the battery pack in order to protect it. Various features, such as Tesla’s “Sentry Mode” security system and heating or cooling the cabin before you get in, can greatly increase vampire drain.
Here we see vampire drain sapping the proletariat of the will to resist their aristocratic masters.
As a mildly educated guess, I’d say climate control and vampire drain may add an extra 15% to average energy consumption per km driven4. This increases the number of full cycles that will occur before the warranty’s km is hit, but this adjustment only means the battery pack will be fully cycled 15% as much as the Powerwall 2 warranty allows instead of 13%.
Combined Cycle
There’s also a reason to think that electric cars will use less energy per km than the EV database figure suggests. This is because it’s for a combined driving cycle that assumes the EV will be driven 50% on highways and 50% in town. In practice, the majority of km will be done on town and city roads and — unlike internal combustion engine cars — EVs require less energy per km for urban driving than on the highway.
I’m not going to try to adjust for this for three reasons:
- I don’t have good information on the split between town and highway driving.
- If my estimate is off by 50% either way, it won’t change the fact that EV battery pack warranties cover far fewer full cycles than home battery warranties.
- I’m lazy.
Other Tesla EV Models
If I use the EV Database figure for energy consumption but bump it up 15% to account for climate control and vampire drain, then the Tesla Model 3 Rear Wheel Drive will fully cycle its battery around 422 times before its km limit is reached. This is only 15% as many full cycles as the Powerwall 2 warranty allows.
The battery pack warranties for most other Tesla vehicles allow them to be driven more km, as you can see here:
But because most other models have larger battery packs, it doesn’t make much difference to the number of full cycles their warranties allow. Below I’ve listed approximately how many times the battery packs of different Tesla electric vehicles can be fully cycled before they reach their warranty’s km limit.
I’ve used the EV Database energy consumption figures for mild weather driving and bumped them up by 15%. I’ve also given kWh figures, which are how many usable kilowatt-hours of battery storage the EV Database says these vehicles have – but note Tesla can vary the capacity of battery packs. The EV Database doesn’t have information on the Model Y Rear Wheel Drive, so it’s not included:
- Model 3 Rear Wheel Drive (57.5 kWh): 422 full cycles — 15% as many as a Powerwall 2
- Model 3 Long Range (75 kWh): 404 full cycles — 14% as many as a Powerwall 2
- Model 3 Performance (75 kWh): 470 full cycles — 17% as many as a Powerwall 2
- Model Y Performance (75 kWh): 470 full cycles — 17% as many as a Powerwall 2
- Model S (95 kWh): 434 full cycles — 16% as many as a Powerwall 2
- Model X (95 kWh): 538 full cycles — 19% as many as a Powerwall 2
Their warranties only cover from 14-19% as many full cycles as the Powerwall 2 warranty. The Model X is a full three percentage points ahead of the other Tesla vehicles thanks to having the highest energy consumption per km.
BYD Batteries
The warranty of BYD home batteries lasts for 10 years or until they supply around 3,050 kilowatt-hours of stored energy for every kilowatt-hour of usable storage capacity. A new BYD HVM home battery with 13.8 kilowatt-hours of usable storage can provide 42,690 kilowatt-hours of stored energy in total before hitting its warranty limit. This is 3,093 full cycles and 10% more than the Powerwall 2 warranty allows.
However, the BYD warranty only promises a minimum battery capacity retention of 60%, rather than Tesla’s 70%, so I consider BYD’s warranty to be worse for typical households.
While BYD hasn’t sold many electric cars in Australia, they may sell a considerable number of their new Atto 3, as the standard range version will have an on road cost of around $45,000 or less. That’s not cheap, but it is cheaper than plenty of other cars, whether EV or conventional.
The warranty for the Atto 3 battery pack is similar to the one for Tesla’s Model 3 Rear Wheel Drive, as it has…
- An 8 year time limit
- A 160,000 km limit
- A battery capacity retention minimum that’s 70% of the original capacity
But the warranty requires the vehicle to be serviced at least once per year, and this makes it worse than Tesla’s warranty.
The EV Database doesn’t have information on BYD vehicles, but — as far as I can tell — the Atto 3 appears to use around 19% more energy per km than the Tesla Model 3 Rear Wheel Drive. The battery pack of the extended range Atto 3 is similar in size to that of the Tesla vehicle and, using the same same assumptions for climate control and vampire drain, can be fully cycled around 490 times before reaching its warranty’s km limit. This is only 16% as many full cycles as the warranty of a BYD home battery allows.
The standard range Atto 3 has a 17% smaller battery pack and can be fully cycled around 590 times before reaching its warranty’s km limit. This is still only 19% as much as a BYD home battery.
Full Cycles In Actual Use
On average, Australians drive private cars around 13,000 km a year. For a Tesla Model 3 Rear Wheel Drive, this represents around 34 full cycles. That’s an average of under one full cycle every 10 days.
A Tesla Powerwall 2 home battery that’s only used for home storage and isn’t part of a VPP may be fully cycled an average 0.8 times a day by a home with well above average electricity consumption. That comes to 292 full cycles a year. This is 8.6 times more full cycles per year than the EV.
After 8 years, which is the maximum time period the EV battery pack warranty will last, the number of full cycles each will have undergone will be:
- Tesla Model 3 Rear Wheel Drive: 272 full cycles
- Tesla Powerwall 2: 2,336 full cycles (2,920 full cycles by the end of its 10 year warranty.)
That’s a huge difference in the amount of work they’re expected to do. After 8 years the EV battery pack discharges less than 12% of the full cycles of a Powerwall 2. The more a battery is fully cycled, the more likely it is to develop a problem. The relatively low number of cycles required from EV battery packs greatly improves their chances of reaching the end of their warranty without issue.
If the Model 3 Rear Wheel Drive battery pack delivered as many full cycles as the Powerwall 2 warranty covers, it could drive over one million km. That’s enough to get to the moon and back and nearly get to the moon again5.
It’s Not All Easy For EV Batteries
EV battery packs have it easy compared to home batteries in terms of the number of full cycles their warranties cover, but their lives aren’t entirely a bed of roses. Additional challenges they face include:
- High power draw
- Temperature extremes
- Vibration
- Lightweight design
Because home batteries have it far easier in these areas, optimising them for durability is easier.
High Power Draw
The biggest difference between an EV battery pack and a home battery is how much power they’re expected to provide per kilowatt-hour of energy storage capacity. (Here’s an explanation of the difference between power and energy if required.)
Ignoring minor DC to AC losses, a Powerwall 2 normally never discharges more than 5 kilowatts of power. At that rate, it would discharge 37% of a full cycle in one hour. A Model 3 Rear Wheel Drive may have to supply 208 kilowatts for brief periods. If maintained for an hour — which is impossible — it would represent 360% of a full cycle. The Model 3 Performance EV can briefly draw up to 377 kilowatts, and if maintained for an hour, that would be 500% of a full cycle.
This high power draw puts the batteries under considerable strain and is a major reason their warranties don’t cover as many cycles or years as home batteries.
When high power is used to fast charge an EV, it also puts the battery pack under strain. This is why EV manufacturers normally recommend limiting fast charging.
Temperature Extremes
High power drain heats batteries, and parking an EV in the sun can also raise its temperature. The hotter lithium batteries get, the faster they degrade. Most EVs have active cooling systems that can protect the batteries if necessary, but if the EV isn’t charging, it’s Catch-22 because energy used to cool the battery pack has to come from the battery pack. Home batteries also have to deal with high temperatures in summer, but as they’re not likely to be driven hard and then parked in the sun, the problem isn’t as extreme.
Vibrations
EV battery packs are also exposed to a lot more vibration than home batteries. It isn’t as bad as you may think because most of the vibration in conventional cars is the result of engines that run off explosions. But Australian roads are not smooth, mirror-like surfaces. Even with decent suspension, this means an EV battery pack will be exposed to far more vibration than a home battery.
Lightweight
The lighter an EV battery pack is, the better since it has to be driven around; but weight isn’t a major problem for home batteries. A lightweight battery isn’t necessarily less durable than a heavier one but, generally speaking, it’s going to be easier to design a durable battery if you don’t also have to worry about how heavy it is.
It’s Easier To Screw People Over With Bad Home Batteries
Car manufacturers have reputations based on their vehicle’s reliability. Some have better reputations than others…
…but none want their reputation to grow worse.
A car manufacturer cannot afford to sell electric vehicles with failure-prone battery packs. Ensuring they’re both safe and reliable is a major reason why large manufacturers such as Toyota have been so slow to offer EVs outside of countries with low expectations for reliability.
When a car breaks down under warranty, people are very quick to let the dealer know about it. Most people depend on a working car to get through their daily lives, and if they don’t receive a rapid response to warranty claims, they will complain about it bitterly. Reliability issues are huge headaches for car companies, and major problems that result in recalls and battery pack replacements will cost them a fortune. They have powerful incentives to get it right.
But companies selling home batteries are in a very different situation for the following reasons:
- Home batteries are a new technology, so people don’t have the same expectations for reliability as they do for vehicles.
- Home battery manufacturers may not have been around long enough to develop a reputation. This means they have less to risk by selling unreliable products.
- If a company has a reputation in other areas, they can expect poor publicity from unreliable home batteries to only have a limited effect on their other areas of business.
- When a home battery that’s used on-grid fails, it’s less of an immediate problem than a car breakdown because the household will still have power. This makes a home battery breakdown less costly to the consumer. There are a considerable number of people who have defective home batteries at this moment and don’t even realize it.
- There’s no direct competition. While it’s possible to install a generator for backup power, if you want to store solar energy for use in the evening, your only real option is to buy a home battery. (This may change as options for electric cars to supply power to homes improve.)
Because they’ve been able to get away with it, home battery manufacturers have been using customers as unpaid beta testers for products that weren’t ready for market. This approach seems to have worked for Tesla, as Powerwalls installed now are generally reliable.
But many other manufacturers have disappeared because of reliability issues — and others will potentially disappear as problems in batteries they’ve already sold come to light. Even large companies with plenty of battery experience have had major problems.
Large car companies can’t get away with providing electric vehicles with anywhere close to the low average reliability of home batteries. Not without ruining their reputation. They not only face competition from other EVs, but conventional and hybrid vehicles as well. Tesla tried launching their Model 3 EV without taking time to address quality and reliability issues and — despite their battery packs functioning acceptably — it nearly destroyed the company.
Some EV Batteries Will Fail Early
The battery packs in most electric cars sold today will operate without problem for the duration of their warranties and will continue to be problem-free for years afterwards. I expect the large majority of electric cars sold now that are on the road in 15 years will still have the same battery pack they had when their warranty ended.
But EV battery packs are still a relatively new technology and are continually being tweaked and improved. It’s inevitable some major car manufacturers will sell EVs with defective battery packs. If these are replaced without fuss under warranty, then it’s not a serious problem for owners.
A worst-case scenario is if the manufacturer has installed so many lousy battery packs they go bankrupt, causing warranty support to disappear. It’s possible to protect against this by buying electric vehicles from companies in good financial condition. EV manufacturers are currently going through a lot of effort to protect themselves from this type of disaster.
Another situation that isn’t worst case, but still bad case, is if a battery pack is just good enough to survive until shortly after its warranty is over. This would be really annoying. On the bright side, Australian Consumer Guarantees provide some protection against this, and you may be able to get a car manufacturer to provide a remedy, even if the written warranty has expired.
I’m not expecting a large number of EV battery packs to fail soon after their warranties end. This is because, to limit costs, EV manufacturers only want to be required to replace a limited number of battery packs at their expense. This means the average battery pack has be reliable enough to last well beyond the limits its warranty allows.
Some people are paranoid about planned obsolescence and companies intentionally producing battery packs that fail soon after their warranty periods are over, but this is very unlikely. If a manufacturer was caught doing this, its reputation would, or at least should, be destroyed.
They also — should — suffer severe legal consequences. Producing electric vehicles designed to fail is environmentally harmful, and legal penalties similar to — or more severe — than those for the various emission scandals makers of conventional cars have engaged in seem appropriate.
Future Improvement
At the moment, for people with typical driving habits, most EV battery pack warranties will last eight years. But I don’t see any reason why this couldn’t be 10 years or more with current battery technology. Currently, it’s usually only eight years because manufacturers know there is a risk their battery packs have defects, and they keep warranty periods short to reduce this financial risk.
Short warranty periods aren’t great for consumers, but on the bright side, it does let manufacturers charge slightly less for their electric cars than they would otherwise.
There’s good reason for future optimism. Once manufacturers become confident their batteries are reliable, warranties should improve. Current lithium battery technology is sufficient for EVs to replace conventional cars but, provided solid-state lithium batteries become affordable, we may see battery packs with million km warranties in the future. But don’t expect them any time soon. They would have to be used for a considerable time before manufacturers have the confidence to provide that kind of warranty.
TL;DR
Canberra Battery Test Centre results have shown abysmal reliability for home batteries. The situation isn’t as bad as it seems, as you can improve your chances by buying from a manufacturer with a good reputation and using a top-notch installer, but it’s definitely not good news.
While some electric vehicles will have problems, in general, EV battery packs will prove far more reliable than home batteries have been so far. The main reason is that they will be fully cycled far fewer times per year than home batteries. Also, car manufacturers have much stronger incentives to provide reliable products. They have reputations to protect and face stiff competition.
While it’s inevitable some electric cars will suffer battery pack problems, most will be dealt with under warranty, and I expect the typical EV battery pack will function for many years after its warranty ends.
Footnotes
- as per the usable energy capacity (kWh) on its data sheet ↩
- BYD is currently selling more electric cars than Tesla, but the Model 3 appears to have been the best-selling individual EV so far. ↩
- This does not mean other EV manufacturers’ range figures can be trusted. ↩
- This 15% figure is for a car driven at least 20,000 km a year and hits its warranty limit of 160,000 km before hitting its 8 year time limit. If it was driven the average annual distance of around 13,000 km, I would increase it, as the portion of energy consumption lost to vampire drain would be greater. ↩
- But this only works if there is a road, gravity doesn’t operate the way we think it does, and the amount of heating and cooling required doesn’t change in the vacuum of space. ↩
About Ronald Brakels
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Great piece as always, thank you. With demand I think we’ll see exponential innovation in battery technology. This one caught my eye: https://www.freethink.com/environment/lithium-sulfur-battery
Hopefully, we will get cost-competitive lithium-sulphur batteries out of that discovery. These things rarely pan out the way optimists hope, but every now and then they do, so fingers crossed.
I tried to get batteries for my solar system from two of the “new technology” manufacturers based on my being a beta test site. Neither was interested. I was hoping for one of the “flow” gel batteries but was disappointed. Maybe soon? No names sorry.
“my being a beta test site…”
You mean like an influencer, you tried to get them for free ?
A very well written article with product comparisons, specifications, consumer views, engineering views, and realistic expectations.
Thank you!
Would the home batteries cycle as much if they were similarly size to EV batteries ie 50-60kwh?
Home batteries that large would be cycled much less because few households regularly consume more than 15 kilowatt-hours overnight. In a situation where a Powewall 2 is fully cycled 290 times a year, a 50 kilowatt-hour home battery may only be fully cycled 87 times a year. But this still comes to more than a 50 kilowatt-hour EV battery pack would be cycled if it was driven the average distance of around 13,000 km per year. (Note that many small cycles will add up to one full cycle.)
I’d been planning to restrict the batteries in my off-grid build, supplementing with an EV with V2H, but your article prompts me to reconsider. The low cycle life of EV batteries suggests that an extra home battery might be a worthwhile investment. Who can say for certain how long a replacement EV battery will be available, given the rapid rate of change? Tesla is flying from 2170 through 3680 to BYD blade battery packaging, and from ternary lithium to LiFePO4 chemistry, with who knows what next. Biofuel at reasonable cost, for the generator, would be a cheaper alternative, I guess. Spare parts prices on an EV battery significantly exceeded the cost of a new car on the Polestar 2 for one driver in China recently, I heard.
Erik Christiansen,
“Biofuel at reasonable cost, for the generator, would be a cheaper alternative, I guess.”
Nope.
https://www.transportenvironment.org/discover/biofuels-are-twice-as-expensive-as-fossil-fuels/
No Geoff, it’s not “Nope”. The post topic, and thus the comparison, was not with fossil fuels, but with a home battery. The $14k cost of a Powerwall pays for many decades of occasional running of a 3.2 kW Honda generator to fill in when there are _consecutive_ days of negligible insolation. Granted, distilled dinosaur is cheaper, but a little diesel generator runnibg on sunflower or rice bran oil would be an improved use for these oils with unhealthy omega-6 to omega-3 ratios.
A decrease in food availability can only help contain the runaway human population, with beneficial effects on elbow room, house prices, and the environment. A population crunch 30 years ago might have helped limit the toasting which is encroaching on our children at a rate of knots. (The Thwaites glacier could rip by 2025. That’ll wake a few of the somnolent.)
Erik Christiansen,
“The $14k cost of a Powerwall pays for many decades of occasional running of a 3.2 kW Honda generator to fill in when there are _consecutive_ days of negligible insolation.”
Erik, have you actually crunched the numbers?
What’s your specs (including fuel consumption) & estimated cost of installing an off-grid genset?
What’s the fuel cost/litre that you estimate to run the genset over the next decade?
How many hours on average per year do you estimate to run your genset?
What other maintenance/service costs for the genset over it’s operating life?
Have you done a sensitivity analysis for a rising fuel price & a range of running hours?
https://www.solarquotes.com.au/blog/cairns-network-battery-mb2535/#comment-1478894
“A decrease in food availability can only help contain the runaway human population, with beneficial effects on elbow room, house prices, and the environment.”
Careful what you wish for – you might just get it! Decreasing food availability increases food prices & worsens social instability. Rising food prices will increase your costs of living, including running your genset (if using biofuels).
“The Thwaites glacier could rip by 2025. That’ll wake a few of the somnolent.”
It seems it’s perhaps already too late for the Greenland Ice Sheet. Glaciologist Professor Jason Box says: “Technically now, Greenland is beyond its viability threshold…”
https://www.solarquotes.com.au/blog/2022-election-clean-energy/#comment-1437698
Geoff, the cost competitiveness of my off-grid genset vs a $14k – $15k Powerwall for domestic energy infill is inevitable for many years to come.
I have two Honda generators, one as standby and for dragging down the paddock. When the 20 year old one sagged to only 190 Vac, I replaced the capacitor in the primitive ferroresonant voltage regulation circuit with a 20 uF motor run capacitor, at a cost of $7, so maintenance cost is not significant so far.
There seems to be more consecutive days of heavy overcast in the warmer half of the year, in Gippsland, than in decades past, with maybe a few less in winter. My guess of 20 to 30 days annually, each with a 4 hr run, will take many years to eat the price of a home battery. If a very attractive battery technology should be developed in the future, then the generatprs can be pensioned off. It is though as Finn says, batteries are still rather pricey. (Though not as pricey as running the generator every night.)
Ah, your warning about the Greenland Ice Sheet is sobering, even if a substantial melt may take some centuries. (I don’t believe the wishful “millenium” estimate.) Thwaites glacier will be sudden, but only raise mean sea level by a foot or so, compared to more than 7 metres for the GIS. The planetary experiment is well advanced, and we’re still making the consequences worse on an industrial scale, with much more talk and planning than completed action. Neither nonlinearity nor feedback appear to be adequately modelled, so overshoot is now going to be civilisation-changing to an extreme degree. It’s not so much a matter of what we wish for as what we act for, and we have acted for a millenium of civilisation-scale disasters, increasing in severity from the small stuff tickling us now. High ground, water supply, energy independence, and local food supplies will count for a lot.
Climate DESTABILISATION is the word. This will kill us, Australians can not migrate into the cool latitude of the Great Southern Oceans, nobody in the southern hemisphere.
Now my point is the new EV should be able to self park.
So every building is connected to the grid and every EV should be able to ‘self nuzzle’ up to a wall plug at bumper height and trade stability and energy with the grid. Ezi pezi.
Huge EV batteries can easily handle the daily drive 14kwh and the home overnight 7kwh and be topped up daily from the grid.
The home 33kwh daily supply can feed some into the grid.
My home use is only 7kwh daily.
The EV battery can be softly topped up daily for years and years.
Little home batteries, 14kwh, maybe a total waste.
The EV battery comes for free with the vehicle. Hahaha.
Here is an idea. I have a larger solar array (9.2kw panels on a 7.1 Fronius 3 phase Inverter). Typical home batteries cost about $12-15k incl fitting. I can buy a used small EV such as a Mitsubishi I-Mev for about the same price.
Now, let us assume just for the purposes of this discussion that my Fronius and the I-Mev can manage V2H loads. I know the I-Mev can’t do it. not sure about the Fronius.
The I-Mev has a 42kw/h battery when new. Would it be a viable option to buy a used EV instead of a battery and use it then for V2H and for minimal round town use charged from my panels.
I ask because I can neither afford nor wish to buy a new EV at this stage.
At present there are no commercial V2H systems available. The ones in the pipeline seem to be quite expensive, so you could another 10k onto that used imiev, which makes it much less attractive. Since the technology to do this is really just a reconfigured solar inverter which are available for only a couple of thousand, I would imagine prices will come down to reasonable levels fairly soon.
I did point out that this was not possible with my Fronius and the iMEV. The idea was purely for discussion of the potential..
My question still remains. Would it be a practical proposition, including for the occasional road use of the car – or even excluding it?
Would love to see a discussion of this, perhaps even if it is possible to modify an EV and inverter to do V2H and whether that would be prohibitively costly..
Come on brains trust – how about some ideas?
Can I suggest that a bigger rooftop that over feeds the grid at a low feed in tariff during the day so that the smaller night time consumption from the grid at a higher rate may equal out, and the battery will not be so necessary.
Great article as it brings into focus the risk consumers carry with the introduction of new tech into the home. For many years I worked in the high end computer industry on large data centres where we used very large scale UPS systems based on a combination of large batteries and onsite generators. The battery systems were always problematic when it came to long term capacity and reliability management. We reduced the risk with smart load shedding where critical systems were protected by automated shutdown of less critical systems using software that safely closed application before dropping supply. I think similar outcomes could be achieved by better load management in the evenings with things like turning off or limiting the current to hot water heaters or delaying the car charge til later in the evening. Re the car do we use a battery on wheels to manage high demand in the evening then charge from the home battery late at night. Compute is cheap and making our homes smart can be used to better manage our expensive and possibly fragile first generation battery solutions.
Tesla batteries are insanely flammable.
They use the most unstable and dangerous battery chemistry in order to get INSANE and LUDICROUS performance.
Comes at a price.
August 26, 2022 NHTSA ID NUMBER: 11481466
Components: FUEL/PROPULSION SYSTEM
NHTSA ID Number: 11481466
Incident Date July 31, 2022
Consumer Location Unknown
Vehicle Identification Number 5YJ3E1EB7MF****
Summary of Complaint
CRASHYes
FIREYes
INJURIES0
DEATHS0
This is a complaint about the unacceptable fire risk that affects all Teslas due to the dangerous battery chemistry and the vulnerability to impact damage that can trigger an instantaneous fire . The VIN of a random Tesla has been used. This problem affects every Tesla. Here is a video of a test conducted by a European testing authority which shows the Tesla igniting almost immediately after a deliberate crash that only caused a minor strike to the underside. https://www.youtube.com/watch?v=QRDCKfCdh90 When NHTSA and many other testing authorities perform crash tests on Teslas they should do so with a fully charge battery that is warm from charging or from having being driven. This is a much more realistic scenario than using cold depleted batteries that are less prone to instant ignition. By comparison with a Tesla the Pinto was just a damp squib. And yet it was recalled and grounded. Please do the right thing before even more people get burned alive. Thank you
We definitely want electric vehicles to be safe as reasonably possible. Of course, the same goes for vehicles hauling around 50+ litres of potentially explosive petrol.
And petrol explodes somewhat more spectacularly than the battery failure shown in this video and will engulf the entire vehicle in no time.
According to findings pointed out by AutoInsuranceEZ, vehicles that operate using gasoline are tenfold more likely to catch fire compared to EVs.
Car fires by vehicle type:
* Hybrid: _ _ 3,474.5 fires per 100k sales _ _ 16,051 total fires
* Gas/petrol: 1,529.9 fires per 100k sales _ 199,533 total fires
* Electric: _ _ _ 25.1 fires per 100k sales _ _ _ _ 52 total fires
https://www.autoinsuranceez.com/gas-vs-electric-car-fires/
Perhaps we should ban ICEVs? Much more dangerous! ?
I think you’ll find that BMWs self imolate more frequently than Teslas.
https://www.abc.net.au/news/2022-03-10/bmw-recalls-more-than-1-million-vehicles-over-fire-risk/100897448
Keef Wivaneff,
“This problem affects every Tesla. Here is a video of a test…
It seems to me the video you refer to is a fake. Today, The Driven posted an article by Bryce Gaton headlined Batteries not included: EV crash fire faked for insurance company video, including:
https://thedriven.io/2022/09/08/batteries-not-included-ev-crash-fire-faked-by-insurance-company-demo/
“Falsehood flies, and the Truth comes limping after it.” – Jonathan Swift
I’m interested to know if V2H increasing the cycles in an EV has a material affect on the EV’s battery life or if the large battery capacity reduces this risk? Investing funds into an EV that can be used by the home seems to be more economic that a home battery, provided the EV battery can cope with the additional load?
EVs providing energy to homes will have an effect on battery pack life, but:
1. If the EV only provides a tiny portion of the power it’s capable of, the effect on the battery pack will be very minor.
2. Wholesale electricity spots prices can reach $15.50 per kilowatt-hour. (And can potentially go higher if other charges are added in.) If a car discharges just 50 kilowatt-hours to the grid over a year, but at an average price of $10 per kilowatt-hour, that represents a $500 payment for the household, which is worth far more than the small amount of degradation that will result.
So, in the future, people may want both. A dedicated home battery that handles most night-time energy consumption, and a bidirectional EV charger so they can take greater advantage of high wholesale electricity prices when they occur.
We’ll just have to see how things turn out.
I wonder if the house battery test of many complete cycles per day was one of the causes of battery failure? This is running flat out over and over, while houses rarely run flat out and rarely use 1 full cycle in one day. It would be the same as driving an electric car at maximum speed for a thousand km a day every day. Most machines aren’t designed to function continuously on turbo. So I am also wondering if you get this many failures reported to you from house battery users under average conditions? The most accurate measure of reliability would be the people who have been the early adopters, like yourselves.
The accelerated testing used could definitely have contributed to greater battery capacity deterioration than would occur in typical household use. But it should not have led to the problems the majority of batteries tested. None of the batteries were used in a way that was not permitted by their warranties.
Thanks for the analysis!
Regarding your statement “I know from fun earned experience that Tesla’s figures for range can’t be trusted”, can I just say that I own a Tesla, and it consistently achieves better range than the car’s stated value. This is for around-town driving – obviously for freeway driving efficiency will be lower, but many people will drive more distance on local roads than on the freeway. I would say that it’s much easier to achieve Tesla’s rating than in any petrol or diesel car I’ve driven, especially diesel cars with DPFs!
I will add that when my daughter drives the car, efficiencly drops noticeably :-(.
I guess that is the challenge with EV efficiency claims. Driving conditions and driver style vary dramatically. As you point out your daughter’s driving habits and yours produce different results. I have a number of coupled friends who say their partner gets significantly different fuel consumption from them – and it isn’t always the bloke who is the higher consumer.
I would rarely if ever achieve the range claims of an EV. I live in an place where I use highways and freeways regularly and I have never met a kw I didn’t love!
But given other aspects of my lifestyle and that I have a larger solar array slow recharging would largely be done at home during the day so mostly range and high charge rates aren’t much of an issue for me. Occasional long distance travel (10000-1700kms only about 3-5 times a year these days) no longer involves the need to rush so only occasional partial fast recharges would have little effect on the life of my EV battery.
The vast majority of Australians would live comfortably with current EV range since they rarely if ever travel long distances, particularly in any hurry or in more remote areas. For many it is the mistaken belief that their actual use would not be accommodated and the comparatively high price and unavailability of EVs which puts them off.
No arguments from me. I guess my point is that people seem to get hot under the collar about EVs not achieving rated range/efficiency, but no-one seems to care that it is exactly the same with ICE cars.
The NEDC rating on the windscreen label is rubbish (for all vehicles), but for me the WLTP rating (which is pretty close to the range the car reports) is very realistic. I have stats for the car from near day 1 and over 35000 kms ,I’m averaging about 5% better efficiency than the Tesla (WLTP) rating. Even with 7% battery degradation over the first 20,000 kms, the car theoretical range (100 down to 0% battery at 105% efficiency) is around 580 kms.
Like you I have plenty of solar and most of my charging is at home – as much as possible self-consuming during the day. I’m using an app that enables (amongst other things) control of car charging so that it only uses excess solar (https://chargehq.net/).
The BBC’s Top Gear show compared the fuel consumption of a Prius being driven as fast as it possibly could around numerous laps of their track, with that of a very high performance BMW M3 driven by Jeremy Clarkson holding close station with the Prius (and having a very relaxed and easy time of it).
Result – BMW used less fuel.
The comment was made – the fuel economy you get is as much to do with how you drive, compared with what you drive.
For the record, years ago the company I worked for as an engineer conducted official fuel economy and emissions testing of experimental and other vehicles. At the time we used the LA4 test procedure – which had been developed in Los Angeles by driving an actual vehicle through the city, for a typical mixture of city street and highway driving. The speed profile was logged, and used for targetted driving on a ‘rolling road’ dynamometer. The dyno accurately electronically simulated vehicle inertia, rolling drag, and aerodynamic (wind) drag. The vehicle exhaust was diluted and captured, and measured with extremely accurately calibrated instruments. The vehicle was pre-conditioned for a typical cold start as per the procedure.
I think a lot of comments I’ve seen reflect very little knowledge in terms of reality.
How do they measure the exhaust emissions of an EV?
What a ridiculous comparison, but then that is Jeremy Clarkson in a word. Sure the M3 may use less if you buy a BMW sports car and drive it at shopping centre car park speeds, while you flog your small car well past the red line.
Ha-a David
What they’d need to do, is measure the filthy emissions of the nearest coal fired power station – that would have had to ‘turn up the wick’ to pick up the extra energy demand to charge that EV, cover the transmission line and transformer losses, battery charger losses, battery losses, etc.
I don’t ‘buy’ Ronald’s ‘blended energy sources’ argument – except where VRE is enabled to be taken out of curtailment. Presently, that would never happen at night – Australia is commonly running at 80% FF-sourced energy at present, or more, shortly after dark (when all the big batteries have run flat following evening peak demand).
EVs not producing emissions is simply a marketing myth.
It is indeed a completely useless comparison as is typical for Top Gear. Firstly, the M3 is a high performance road car also designed for track use. The Prius is a parallel Hybrid primarily for city and urban use. No-one ever buys a Prius to use as a part time track car, plenty of M3 are bought for this reason, some for full time track use.
And no doubt, Top Gear being what it is, entertainment and not a car testing show, to make the comparison even more in the favour of the M3 they ensured the battery was fully depleted at the start.
And to Ian Thompson, given that many people charge their EVs of solar at home or even work or used time controlled charging to low load periods(remember, hydro and wind don’t go to sleep), your claim re loads doesn’t stand up.
Actually, I do disagree with your statement “The NEDC rating on the windscreen label is rubbish (for all vehicles)”. As a long time and regular reader of car magazines and tests here and overseas I have found an increasing tendency for those tests to find that more and more cars are achieving close to or the same as their rated economy figures. It also needs to be acknowledged that motoring journalists rarely drive like the average person, they tend to pedal harder than most, although some longer term tests do try to replicate sort of similar driving patterns to us mortals. Remember though, people tend to load up cars, leave stuff in the boot and around the car etc, add accessories (remember, NEDC tests like WLTP are laboratory tests in absolutely standard spec, not on roads with owners and the detritus of live in them).
A recent test by a caravan suspension company show that the base model Discovery they bought with minimal accessories (no bullbar or heavy stuff) was already well over 100kgs heavier than standard.
Even on my 11yo Skoda V6 wagon I get close to the extra urban rating on country trips without trying hard and have exceeded it when I focus on economy and moderate my speed – I am not normally a slow driver, officer!
Ian Thompson have a look at Tony Seba’s videos.
https://www.youtube.com/watch?v=duWFnukFJhQ
The horse and cart disappeared from streets in 13 years.
The incumbents always fight change, and spread the deceptive information.
Kodak film died with digital image technology growth.
S curved change can be exponential and billions wiped from economies.
China probably hates being dependent on foreign fossil fuel imports.
Solar panels and EV production is ramping up, 10million EV sales this year and maybe 15million next year.
The only thing slowing China is the pandemic.
Tony Seba has documented many changes.
Stranded assets will destroy peoples lives and wealth.
My gut feel (as an engineer!) is home storage won’t be a major component of a future grid, with the development of distributed storage (community batteries, large-scale storage like pumped hydro etc.). Much too difficult to manage millions of household batteries for collective energy storage. EV batteries may be the exception, because there’s better support and servicing infrastructure through the car makers already in place.
There are good financial reasons for “behind the meter” battery storage because homes and businesses pay the retail price for electricity. I wrote about this here:
https://www.solarquotes.com.au/blog/big-vs-home-batteries/
The article is a couple of years old, but the basic point remains.
You win.
No contest. Sometimes I have a gut feeling but after doing research it turns out completely wrong.
Yep just jokes. From the price and functionality side of things, I agree the argument stacks up. From the engineering point of view, I still wonder about scaling, having too high a proportion of national storage in private hands. VPPs add some controls there I guess. We never developed private storage of petrol or gas to any great extent, for example. But we also weren’t producing them at home either, so it’s a difficult comparison, I know.
Is there an article on the site looking at the likely future for feed-in tariffs, with the massive changes coming to the grid, storage, generation etc.? Are they likely to survive? Go up or down? Etc. I’m interested whether generators are looking at that huge PV supply out there, which is still growing, and factoring it into their future generation plans. I’m guessing yes, with the emergence of VPPs. Will there come a day where feed-in tariffs become less important or obsolete? Or will they become more important over time?
There is this one that is now two years old:
https://www.solarquotes.com.au/blog/solar-feed-in-tariff-future/
An update to that is I am now expecting sizable solar feed-in tariffs next financial year, but that may be followed by a large decrease the year after. I’m not expecting them to disappear at any point, but they may go very low.
Thanks, will have a look.
Hi Nick
Yes, certainly ridiculous, but with respect Nick, I think you may have missed the deliberate humour – and the fact that both cars were being driven under identically conditions. The M3 was not being driven at shopping carpark speeds – it was simply matching the Prius – speed for speed, corner for corner.
Your conclusion also appears wrong – if the Prius was driven in a dawdling manner around shopping carparks, I am certain it would achieve better fuel economy than the M3, being driven equivalently.
The point being – if you drive any vehicle hard, you will get poorer fuel economy – even in an EV. I also believe some people think pressing the accelerator pedal as if it were covered in eggshells, will maximise fuel economy – but that is not true – engines run more efficiently at mid-load, and economy is best maximised by accelerating moderately, but to a lower top speed (as wind drag dominates due to the square law) – also by anticipating red lights, and backing off the throttle early to save energy, and also to ensure speed is maintained as high as possible for when the lights go green.
While I agree with most of what you say, I do have to disagree with your statement “some people think pressing the accelerator pedal as if it were covered in eggshells, will maximise fuel economy – but that is not true”.
If you read the book by Hans Tholstrup about his extreme fuel economy driving (he set many world records) he actually says to drive like you have an egg under the accelerator. Plus various guides for improving fuel economy from motoring associations and various other sources talk about using the lightest load for acceleration possible and employing other reduced load techniques including the things you mentioned. I have produced some exceptional improvements in economy by doing this but it does take serious concentration. Your techniques will produce good results though.
I commute a long distance each day (120 km ‘round trip). As an experiment I tried using cruise control and manual throttle control on alternate weeks, and measured the fuel consumption. With cruise control I use 20% less fuel. There is no way a human’s control of a throttle with their foot can be as relentlessly efficient as a machine, particularly now technologies like adaptive cruise control are becoming more common as well. So yes agree, how you use the throttle really matters.
What uses the most energy/fuel is having to generate momentum, accelerating 1-2 tonnes. Anything that minimises that, or even the rate of acceleration, will save the most fuel i think.
Hi Delan
With respect, if you understood the asymptotically reducing efficiency of an IC engine as load is reduced (caused by pumping work, the pistons drawing in air against an increasingly high intake manifold vacuum), then you might think differently. Zero (0) efficiency at idle. No – moderate acceleration is hugely more efficient – the important thing being to keep the top speed down, allowing the engine to work longer at a disproportionately more efficient load (and therefore, efficiency). Even an EV is not particularly efficient at low motor loads – the ‘sweet spot’ is located at mid-speed, and mid-load.
Hi Nick
I use cruise control almost all of the time. But you will note when you increase set speed on a cruise control, the car accelerates at a moderate rate – it does not ‘pussy foot’ around with extremely low rates of acceleration – nor does it floor the throttle. At high engine speeds, and at vert high loads (e.g., Wide open Throttle, WOT, when fuel enrichment comes into play), the engine efficiency falls off a little (but not as bad as at low engine loads).
You comment about momentum is only partly correct – when we used to conduct mixed-cycle emissions testing (and other measurements), the engine output energy (after accounting for water cooling losses, and lost heat to exhaust), was distributed approximately 1/3rd each to braking momentum losses, rolling resistance (in the tyres, bearings, etc.), and wind drag losses. Hence my point about keeping the top speed down – wind drag goes up as the square of speed ( 1/2 * rho * v * v * Cd * A).
Obviously, at freeway speeds, wind drag dominates – but inertia around city streets. Which is why cruise control works so well – it keeps the speed constant – rather than allowing the vehicle to travel faster down hills, losing more energy.
Obviously, if you accelerate heavily, only to then have to brake heavily – and I see plenty of that – then a lot more inertial energy is wasted.
Very interesting. Are automatics now more efficient than manuals these days, as I’ve been told? Or is that only for fancy vehicles out of the price range of average Australians?
Sorry Ronald – I replied at the end of the post in error – meant to reply here.
So – my experience with emissions/fuel economy testing is somewhat historical now – but I do feel vehicle efficiencies have improved out of sight over the intervening years. Even the technology of my 10-11 year old car could get well over 40 mpg in the old scale, while doing 160 kph – my first car was a 998cc Ford Anglia – and this tiny car would barely get that fuel economy, at normal speeds (well, it couldn’t even get to 100 mph, unless falling off a cliff – am I allowed to mention that?).
Looking further down the link I provided:
https://en.wikipedia.org/wiki/Brake-specific_fuel_consumption
it was interesting to see (in the Examples Table), that a General Electric 605 MW CCGT could achieve 62.2% thermal efficiency – that old BMW and AUDI diesels could get 42.6% efficiencies (much better than a Prius). 2011 model Ford Ecoboost at 33.5% – even a 1931 Junker Jumo aircraft engine at 40%. ICE’s are a little more efficient than many people think.
BTW – I suspect the the benefits of regenerative braking (in reducing the 33% braking losses) may be a little overstated (a marketing ploy?). Might work better with Tesla permanent magnet front motor – but my experience is that induction motor regeneration is not very efficient. Interestingly, my car even kicks the alternator up to 14.8 volts during vehicle overrun (and fuel shut-off) – increases the braking effect a little, and saves having to charge the battery a little.
No problem. I saw your reply, I just hadn’t got around to thanking you for it yet. It looks like I can no longer feel smug about having a manual when it comes to fuel efficiency, even if I do drive carefully.
Ha – perhaps you could go for a DSG instead! Essentially a manual gearbox, with automatic control of clutch(es) and shifting.
My wife’s VW EOS convertible had a 6-speed DSG box – I’ve been told it was the fastest shifting gearbox in the world ~ 100msec. Practically, at high accelerations the shifts just felt like someone had tapped the underside of the car with a rubber mallet (and, the tacho shot back).
A lot of fun to drive – but I suspect because of that, not the greatest fuel economy! Had to be a little careful getting off the mark, to avoid tyre-smoking wheel-spin.
Comparing previous cars – I once had a 5-litre VK Commodore HSV – slightly ‘breathed on’ by Peter Brock to raise the stock power from 125 kW, to 139 kW – a 4-speed manual with about 12 L/100km, but HEAPS of torque. My present old car is bigger, heavier, quicker, 180 kW, an automatic, but gets about 6 L/100km. That is still fairly old technology…
Go for an automatic! Sorry – I suppose you are thinking EV…
It’s Clarkson at his disingenuous best. An M3 will not have to work hard to drive the same speed as a Prius, so it will use less fuel. But nobody who buys an M3 wants to drive it at Prius speeds.
No Nick
But, driven at Prius speeds an M3 will invariably burn more fuel.
Hi Ronald
Please see the graph (roll down a bit) of the attached link:
https://en.wikipedia.org/wiki/Brake-specific_fuel_consumption
BSFC is inverse of efficiency (smaller number = better efficiency).
Importantly, the best efficiency operating point of an engine, is at moderate speed but high load (at the ‘eye’ of the graph). The vertical axis shows (absolute) manifold pressure (or, engine torque). The aim is to operate as close to the eye, as possible.
Interestingly, my 10-year-old German family sedan has an 8-speed automatic, is turbo-charged, 180 kW, and I think has a ‘fly-by-wire’ throttle. When driving at WA’s speed limit of 110 kph, the engine is turning at barely 2,000rpm, and would be at a moderately high engine torque (load) – right in the ‘sweet-spot’. When climbing a hill, the engine and transmission electronics talk to each other, and if necessary, coordinate a down-shift (to 7th speed) – almost imperceptibly – you need to be looking at the taco to be aware as the engine goes up to ~ 2,300rpm, still close to the maximum efficiency eye of the graph. So – I suspect no normal driver would achieve much better – and anyway, couldn’t be bothered with an 8-speed manual. The large number of gear ratios helps keep the car efficient (and provides good acceleration for a small-capacity engine) – I commonly get ~ 5.8 L/100km or better in a heavy car, at 110kph.
Back in the day, manuals were most certainly much better than automatics – the torque-converter continuous slip introduced inefficiencies. The introduction of a ‘lock-up clutch’ improved things, but usually only in top gear. The advent of electronics went further – the shifter in my old car is only a ‘joystick’ – it has no linkages.
So – I suspect many modern automatics would do better than a manual – but I recognise my old car is a bit ‘up market’, so don’t really know where the ‘break-even’ is between them. You rarely ever see a ‘stick-shift’ in the USA!
The results of the Canberra battery test were not great but what I did notice was that the warranty did allow for many of them to be replaced. Although this is not ideal it does mean that you may get a new battery several years into it’s life which then resets everything and you would have a good change of getting a useable lifespan. I guess this is why home batteries are going up in price not down as the failure rate means manufacturers have to build in the cost of replacing a high percentage of batteries during their warranty period.
I think as long as you can go with a company that honours their warranty and does not go bust and you keep on top of monitoring so you are aware when it fails then it’s not such a bad thing to have a replacement battery half way thorough it’s life 🙂
Because I cannot find on the Solar Quotes web site, an email address for contacting Solar Quotes (with a suggestion for an article for the blog), and, therefore, cannot forward the email message that I received this afternoon, as a notification, I post this message here.
Friday 9 September 2022 is apparently, World EV Day.
At Forrest Place in Perth, WA, for the third such event in WA, from 1000 to 1900, is “a free event, no registration is required”; a WA exhibition of EV’s.
See https://aeva.asn.au/events/422/
Thanks for the heads up.