EV (electric vehicle) News & Discussion

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#3354900 18-Mar-2025 18:03

Dingbatt:

At the moment the going rate for public charging is about 80c/kWh. With the way NZ’s electricity market works I imagine that will go to $1/kWh in the not too distant future.

So for an EV that does 15kWh/100km, that is 15c/km and add on 7.2c/km for RUC, which is 22.2c/km ($22.20/100km, if my maths is correct). That equates to an ICE vehicle that uses 7.2l/100km (using $3/litre for 95RON).

Since there are plenty of hybrids, many of which run on cheaper 91RON, that will return economy figures way better than 7.2l/100km, you wouldn’t want to get an EV if you didn’t have charging at home or work, if your goal was to save money.

I don't think the math works that way.

Many of the BEV people I know only charge their vehicles on a normal wall socket about once per week which tends not to equate to the petrol tank being filled every week.

I would suggest, an electric motor is not an engine, there are a different set of efficiencies involved. There is also a large difference in the older BEV vehicles based on a normal car chassis (with a similar designed motor such as a PMSM) and say a modern vehicle that is using an Axiel flux motor on each wheel with an electronic axle.

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HarmLessSolutions

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#3354961 18-Mar-2025 18:28

TwoSeven:

Dingbatt:

At the moment the going rate for public charging is about 80c/kWh. With the way NZ’s electricity market works I imagine that will go to $1/kWh in the not too distant future.

So for an EV that does 15kWh/100km, that is 15c/km and add on 7.2c/km for RUC, which is 22.2c/km ($22.20/100km, if my maths is correct). That equates to an ICE vehicle that uses 7.2l/100km (using $3/litre for 95RON).

Since there are plenty of hybrids, many of which run on cheaper 91RON, that will return economy figures way better than 7.2l/100km, you wouldn’t want to get an EV if you didn’t have charging at home or work, if your goal was to save money.

I don't think the math works that way.

Many of the BEV people I know only charge their vehicles on a normal wall socket about once per week which tends not to equate to the petrol tank being filled every week.

I would suggest, an electric motor is not an engine, there are a different set of efficiencies involved. There is also a large difference in the older BEV vehicles based on a normal car chassis (with a similar designed motor such as a PMSM) and say a modern vehicle that is using an Axiel flux motor on each wheel with an electronic axle.

Dingbatt's calcs are sound. It all comes down to what the vehicle consumes per km and the cost of that energy source, be it petrol, diesel or electricity, plus RUCs where applicable. How often a vehicle is charged or refuelled isn't relevant, only the cost of that fuel or electricity and neither does whether you call it an engine or a motor that's providing the propulsion.

Our Polestar2 is almost totally charged at home from our solar so the cost of its 'fuel' is whatever opportunity loss we suffer from not exporting it, and our FIT is 17c/kWh so at ~5km/kWh it costs us ~3.5c/km + 7.6c RUC/km = ~11c/km or roughly half the cost of feeding an equivalent ICE petrol. The 85c/kWh that ChargeNet costs for charging (or over $1 at Tesla charging) brings the cost up to that of feeding an ICE but that situation is very rare for us.

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jonathan18

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#3354979 18-Mar-2025 19:23

PolicyGuy:

In my admittedly limited experience in Oz, one way of dealing with the fact that the local electricity distribution network simply can't cope with really fast chargers is to have the charger include a decent sized battery bank. That way the charger can draw 25kW or 50kW from the local grid - continuously if needed - but deliver much faster than that from the batteries for short periods while a vehicle charges up. The batteries recharge in the gaps between vehicles. This solves the problem that adding a point load of say 150kW would cause voltage instability to other consumers on the long thin rural or rural town distribution network

They’ve tried this in NZ too, in cases re-purposing old Leaf batteries. (eg https://countiesenergy.co.nz/media-centre/counties-energy-repurposes-end-of-life-ev-batteries-to-recharge-new-ev-cars/)

One of the worst black spots in the South Island for EV charging is supposed to be fixed by a similar charger (only 2x50 kW chargers - even those slow speeds are only possible due to the batteries) in Spring’s Junction, but that’s been promised for ages (years I believe); I see a press release in Nov 24 promises action soon, but I can’t see any indication it’s open yet? https://www.meridianenergy.co.nz/news-and-events/media-release-an-oasis-for-south-islands-ev-charging-desert

gzt

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#3354989 18-Mar-2025 20:20

dafman: I cannot imagine why anyone who can’t charge at home would be interested in an EV. “Bye hon, I’m just popping out for an hour to fill up the car”

Depends how many km someone travels in an average week and how long they usually take doing the shopping. Park and shop. It works for some people. It easily works for my usual shopping destinations.

alasta

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#3355052 19-Mar-2025 09:10

gzt:

dafman: I cannot imagine why anyone who can’t charge at home would be interested in an EV. “Bye hon, I’m just popping out for an hour to fill up the car”

Depends how many km someone travels in an average week and how long they usually take doing the shopping. Park and shop. It works for some people. It easily works for my usual shopping destinations.

The experts here will correct me if I'm wrong, but I think 20 minutes of charging at 50kw would add at least 100km of range. There are public chargers at my local supermarket and pool, and I spent at least an hour and a half in those locations each week.

When I'm not travelling out of town I never drive anywhere near 100km in a week so it wouldn't be a problem. I'd be more concerned about range anxiety on longer trips, but that applies regardless of whether you have charging available at home.

sen8or

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#3355054 19-Mar-2025 09:22

I think psychologically theres a difference between the occasional fill at a charging station and a requirement to have to fill at a charging station. It goes from something you do whilst you do other things, to having to do other things whilst you fill up your car. This may just mean a mind / attitude shift for people, but its real none the less.

I used to leave my car on charge at work once a week and even though I rarely use my car during the day, it grew tiresome. Even though its a company car, I now simply choose to charge it at home over night once or twice a week, sure it costs me a few $ in electricity, but the cost is worth as I don't have to consciously make an effort to charge it at work.

SaltyNZ

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#3355055 19-Mar-2025 09:41

alasta:

The experts here will correct me if I'm wrong, but I think 20 minutes of charging at 50kw would add at least 100km of range. There are public chargers at my local supermarket and pool, and I spent at least an hour and a half in those locations each week.

When I'm not travelling out of town I never drive anywhere near 100km in a week so it wouldn't be a problem. I'd be more concerned about range anxiety on longer trips, but that applies regardless of whether you have charging available at home.

Definitely not a problem unique to New Zealand. As with most complicated problems the answer will be a combination of solutions for different environments - centralised DC charging hubs with attached useful services, street-lamp AC charging, greater availability of ad-hoc car rental services (like Lime scooters for cars), AC chargers at workplaces and greatly improving public transport to reduce the need for private vehicle ownership in the first place. They all have a place in our future.

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TwoSeven

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#3355308 19-Mar-2025 18:12

HarmLessSolutions:

Dingbatt's calcs are sound. It all comes down to what the vehicle consumes per km and the cost of that energy source, be it petrol, diesel or electricity, plus RUCs where applicable. How often a vehicle is charged or refuelled isn't relevant, only the cost of that fuel or electricity and neither does whether you call it an engine or a motor that's providing the propulsion.

Our Polestar2 is almost totally charged at home from our solar so the cost of its 'fuel' is whatever opportunity loss we suffer from not exporting it, and our FIT is 17c/kWh so at ~5km/kWh it costs us ~3.5c/km + 7.6c RUC/km = ~11c/km or roughly half the cost of feeding an equivalent ICE petrol. The 85c/kWh that ChargeNet costs for charging (or over $1 at Tesla charging) brings the cost up to that of feeding an ICE but that situation is very rare for us.

Not being pedantic, but I don't think they are. The point I am trying to make, is if one is comparing ver.1. (technology) electric cars with petrol cars, then yes because I would suggest that those vehicles are just normal cars with a different engine. But once one gets into newer technologies (ver. 2+), it is not so comparable for a number of reasons. While the cost of electricity (from an appropriate charging point) and the distance travelled are valid inputs - the calculation does not take into account efficiency, size and capability of the vehicle, usage purpose, technology being used and even the fuel source.

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Dingbatt

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#3355313 19-Mar-2025 18:50

You are being pedantic.

My example was in reply to the question about only using public charging, hence the bit in italics at the end of my post. Noting that if saving money was your objective, then public charging isn’t the way to go.

There is no doubt more efficient EVs will come along. I purposely chose neither the best (about 12kWh/100km) through to the worst (about 22kWh/100) of vehicles I have tested in recent times.

Theory vs real world numbers in NZ.

Edit: I will concede I got the RUC wrong. It’s 7.6c/km not the 7.2c I used in my calculations. But that just makes the economics slightly worse.

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Asteros

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#3355316 19-Mar-2025 19:08

Firstly, I don't know much about electric cars. I see that BYD have announced plans for 1 Megawatt charging in China. How difficult, in terms of cost and infrastructure, will it be to deliver? They are talking about 10C charging. What are the benefits and drawbacks of such high speed recharging?

gzt

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#3355330 19-Mar-2025 20:09

This article does a good summary:

BusinessKorea: BYD further announced that it would apply the Super e-Platform to mass-produced passenger vehicles, delivering 1,000V of high voltage and a charging power of over 1,000 kW–more than double Tesla’s capacity. To support this initiative, the company has begun pre-orders for two new vehicles featuring the platform: the Han L sedan starting at 270,000 yuan (approximately 54 million won or $37,327) and the Tang L SUV starting at 280,000 yuan, both of which are set for release in April. Additionally, BYD plans to install its ultra-fast charging infrastructure to expand the market, with over 4,000 charging stations across China.

Tesla supercharger is now at 350kw with plans to increase to 1/2 megawatt in the near future.

BYD's upcoming is around three times Tesla's current maximum and twice Tesla's short term future plans.

gzt

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#3355331 19-Mar-2025 20:14

I wonder if we'll need to align our current road network

more closely with our grid in some places..

South Island might get some bonus DC charging

gzt

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#3355334 19-Mar-2025 20:32

Asteros: Firstly, I don't know much about electric cars. I see that BYD have announced plans for 1 Megawatt charging in China. How difficult, in terms of cost and infrastructure,

BYD's initial China plan is 4000 new charging stations. China has half a million electric busses on the road. For a country as large as China 4000 stations is a very small number initially. It is a safe bet BYD will be planting 1MW chargers where the available infrastructure is already in place.

everettpsycho

614 posts

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#3355335 19-Mar-2025 20:38

SaltyNZ:

Definitely not a problem unique to New Zealand. As with most complicated problems the answer will be a combination of solutions for different environments - centralised DC charging hubs with attached useful services, street-lamp AC charging, greater availability of ad-hoc car rental services (like Lime scooters for cars), AC chargers at workplaces and greatly improving public transport to reduce the need for private vehicle ownership in the first place. They all have a place in our future.

Definitely going to be different as it transitions. We already see chargers in places where that already exists. Fast chargers in supermarkets and town centre car parks spring to mind. Doing Christchurch to hanmer we always pull in for a top up at Amberley, grab some shopping in woolies and back on our way, we would have stopped there regardless of the charging situation.

More structure to ac charging is what I'd like to see though. They are peppered around but most have little need to use them. Sometimes an hour or two on one of those while you are staying somewhere anyway gets you enough to get you where you're going at half the rate of a dc charger. If you're parking up at work for 8 hours companies should seriously consider installing chargers and charging staff if they wish to not foot the bill. I'd even consider taking even slower charging if it meant more stalls, 3.6kW would be enough over an 8 hour stint for most people and mean double the chargers could be installed on a supply, you'd get 6 stalls at that rating where they install a single 22kW ac charger now that probably seldom sees that rate being utilised.

Scott3

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#3355388 19-Mar-2025 23:43

Regarding EV ownership without the ability to charge at home (or work), generally I advise against it.

Home (or workplace) charging is the sauce that makes EV ownership viable. Without it EV ownership is less convenient than say a comparable Toyota / Lexus hybrid, and with the EV paying more than double the road tax, and public DC charging costs, the EV is going to be a lot more expensive to fuel.

Yes, a longer range EV and a DC charge at a weekly supermarket shop can mean the convenance impact is minimal, but it is still not perfect. My closest few supermarkets do not have EV chargers, and the one that does only has a single (50kW) unit. If it is in use of out of service, I would need to go elsewhere.

Long term we are going to need to make home charging a lot more available (Currently seems quite hard for many living in apartment buildings. At some point I think we need California style legislation which prevents body corps from blocking EV charger installs). Also need some means to make it easier for tenants to get an EV charger installed. Throwing a cord out the window is not so ideal now that EV's with 100 kWh batteries are filtering into the used market.

gzt:

I wonder if we'll need to align our current road network

more closely with our grid in some places..

South Island might get some bonus DC charging

That map is an extremely simplified version of the national grid map, it appears to only show 220 kV lines & The HDVC link.

Should note that the 220 kV it is actually pretty useless for most customers. A 220 kV connection is very expensive, and if a new substation is required it is in the area of $30m. Generally can need load / generation well north of 100 MW to justify a 220kV connection.

Full network maps are here.

https://static.transpower.co.nz/public/uncontrolled_docs/Transmission-map-north-island0723.pdf?VersionId=uAm0aiDpEfF2eVATryjJaCbEj3kj7hGM

https://static.transpower.co.nz/public/uncontrolled_docs/Transmission-map-south-island0723.pdf?VersionId=x9vxV4T0y7jhqf_vmqgmB0bMxhPwSCb9

Then under this sits our numerous distribution networks, for example Vectors network is below. Not all of this has available capacity for multi megawatt loads, but many feeders and sone subs do. And vector will upgrade capacity for a customer if needed (but there is a cost to this)

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