EV - DC home charger

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#2840806 31-Dec-2021 14:16

ShockProof:

Any car charger built for NZ domestic will be single phase as it is assumed that a home doesn't have three phase power (but I do). The top limit is going to be about 11 kW as that is going to use a 50 A circuit breaker.

Sorry, but that's wrong.

1) When AC charging, the charger is on board the car itself, not external. The EVSE basically tells the car the available current per phase and provides some safety protections
2) Almost every locally available EVSE has single and 3 phase versions available for the NZ market. You may have assumed that homes only have single phase, but the manufacturers and suppliers do not
3) 11kW equates to 16 amp 3 phase in NZ. AFAIK it is only countries with 110v mains that normally draw more than 32 amp / phase for an EVSE, because they have to get a high current 220v single phase circuit installed for charging
4) A 3 phase variant of an EVSE seems to be a couple of hundred dollars dearer than single phase in NZ
5) Any car with a charger pulling more than 7kW (approx) will have a 3 phase onboard charger
6) With DC charging, the charger is external to the car, so you are buying an actual charger, not just a device to signal and switch the current. That's why they are more expensive

There are several 25kW DC chargers available, like this, but for most people the cost will be prohibitively expensive, particularly if the intention is to save money by utilising free power time slots. If you have 3 phase available, go for a 22kW 3 phase EVSE as the most versatile and cost effective. The bulk of cars currently available will only draw 16 amp 3 phase (11kW), but if you plug in a single phase car, you'll have the full 32 amp available (rather than only 16 if you went for an 11kW 16 amp 3 phase EVSE). There is the odd car that will draw 22kW (eg Zoe) but not that common yet.

As an example an NZ new BMW i3 has 3 x 16 amp single phase chargers on board. Depending on what power source it is connected to, these will connect 1 to each phase, or 2 in parallel to a single phase to draw a max of 11kW 3 phase or 7kW single phase.

ShockProof

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#2840888 31-Dec-2021 16:10

RunningMan:

ShockProof:

Any car charger built for NZ domestic will be single phase as it is assumed that a home doesn't have three phase power (but I do). The top limit is going to be about 11 kW as that is going to use a 50 A circuit breaker.

Sorry, but that's wrong.

etc.

Yes, already admitted that I got that wrong. There isn't a lot of information on the brochures that come on-line for the vehicles that I have been looking at. Also new to EV so still working out what is what. But it is a good surprise that over 7 kW the manufacturers are using 3-phase AC input.

My new house has 3-phase power installed and I have two five core cables in the garage walls for future EV connection points be they AC or DC.

My thoughts on a 15 - 20 kW DC car charger are blown away by a 22 kW AC charging Renault Zoe EV. Much better solution than going DC. I would only need to get a 3-ph interface installed on one of my 3-ph cables, which are 32 A rated I think (will have to ask sparky what they put in). This is called EVSE I see. It seems to be a negotiator between the available AC supply that I have and the battery charger installed in the car, and does EV metering as well, and a bit of protection service and some other nice to have stuff.

Obraik

2123 posts

Uber Geek

#2840897 31-Dec-2021 16:31

ShockProof:

My thoughts on a 15 - 20 kW DC car charger are blown away by a 22 kW AC charging Renault Zoe EV. Much better solution than going DC. I would only need to get a 3-ph interface installed on one of my 3-ph cables, which are 32 A rated I think (will have to ask sparky what they put in). This is called EVSE I see. It seems to be a negotiator between the available AC supply that I have and the battery charger installed in the car, and does EV metering as well, and a bit of protection service and some other nice to have stuff.

I wouldn't buy a Zoe just for the 22kW charging capability, unless it was used and suits your needs.

The 11kW provided by many 3 phase vehicles is likely to be more than enough. At 11kW, even a long range 100kWh vehicle could get from 5% to 90% in just over 8 hours.

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RunningMan

8957 posts

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#2840938 31-Dec-2021 18:24

I certainly wouldn't buy a Zoe just for charging capacity. Not saying don't get one, but the difference between 11kW & 22kW AC shouldn't be a deal breaker. The Zoe (unless brand new) can't DC charge so you don't have any option for faster charging when you forgot to charge or need to charge quicker due to a long distance drive. Good city car and capable of longer distance, but would require careful planning and long charging stops. More often than not a type 2 you find out and about will only be single phase anyway so you'd be sitting still for a long time.

A couple of locally available 22kW options for you

https://wallpods.co.nz/shop/neuton-power-wallpod-evse-type-2-tethered-3ph-32a22kw

https://oemaudio.co.nz/electric-vehicle-charging-products/EV-Power-32-Amp-22-kW-WallCharger-3-Phase

https://www.evnex.com/ (NZ made)

RunningMan

8957 posts

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#2840945 31-Dec-2021 18:40

ShockProof:[snip] There isn't a lot of information on the brochures that come on-line for the vehicles that I have been looking at.

Very true. Manufacturers seem to be providing more info on what the on board chargers are, but sometimes it comes down to a bit of arithmetic from the battery capacity and quoted charge time. It will almost always be 32a single phase or 16a 3 phase (7 or 11kW respectively). There's the odd exception - Zoe - some Tesla models had 3 phase 20 amp? - Leaf with the 3.5 or 6kW - but most of those are older vehicles.

ShockProof

31 posts

Geek

#2841215 1-Jan-2022 09:45

I am looking at new cars first. My general opinion of Renault is don't buy, but that is based on ICE cars. It's just a quick judgement based on low sales and big distances to the spare parts warehouses. Also from looking at reliability stats for vehicles, most European brands don't do very well. I would have to do a lot of checking before I could satisfy myself that a Renault Zoe was a good idea.

I understand what you are saying about 11 vs 22 kW in real world charging. I need to do a lot more work on electricity tarrifs that suit EVs and the real savings if i want to get the best plan. I guess a Zoe type battery wouldn't charge at 22 kW for 3 hours anyway, and as everyone is pointing out, it wouldn't really start at zero charge.

I am still a looking at the new Nissan Leaf and its slower charging rate of 6.6 kW 1-ph. And being aware that Renault owns a big part of Nissan and votes on their board. Not a perfect world.

This is giving me a lot to think about.thanks to everyone who is providing help and advice.

Obraik

2123 posts

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#2841306 1-Jan-2022 10:52

Do not buy a brand new EV that has no active thermal management of its battery as you will see battery degredation with those vehicles. This includes both the new Leaf and Zoe. The new Zoe also has a 0 star crash rating to boot.

Any of the new EVs with thermal management is a good choice...even the MG ZS EV has water cooling of its battery.

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ShockProof

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Geek

#2841337 1-Jan-2022 12:15

Obraik: Do not buy a brand new EV that has no active thermal management of its battery as you will see battery degredation with those vehicles. This includes both the new Leaf and Zoe. The new Zoe also has a 0 star crash rating to boot.

Any of the new EVs with thermal management is a good choice...even the MG ZS EV has water cooling of its battery.

Good point. Water cooling sounds like future maintenance expense to me. Probably effective, but leaks? Air cooling sounds like a cheaper future repair if it faults (fan dies for example). Water is always trying to get out of any enclosed system but any means possible.

Obraik

2123 posts

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#2841341 1-Jan-2022 12:20

ShockProof:

Good point. Water cooling sounds like future maintenance expense to me. Probably effective, but leaks? Air cooling sounds like a cheaper future repair if it faults (fan dies for example). Water is always trying to get out of any enclosed system but any means possible.

Sure, unlikely but it is a possiblity. However, I don't think that risk outweighs all the downsides of an air cooled pack. For a start, just fast charging them is problematic - if you need to charge more than twice in a day you will be suffering reduced charge rates due to overheating. You will also see noticable degredation early on in the cars life and after 10 years you'll likely be needing to replace the battery. An EV with a thermally managed pack should never need its pack replaced.

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ShockProof

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#2841449 1-Jan-2022 14:36

Maybe I should have been clearer. I mean forced air cooled, not natural air cooled. I think this is what Tesla has, for example. I would think the forced air cooled system would be better for long term maintenance than a pressurised water system, which also needs a water to air heat exchanger, and a pump, and pressure relief and so on, so even more parts. Or is it a natural circulation of water, I don't know, just guessing from what I know about water cooled equipment I have worked with in the past.

Dingbatt

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#2841450 1-Jan-2022 14:41

Teslas use ethylene glycol coolant (G48) for their battery packs.

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SomeoneSomewhere

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#2841452 1-Jan-2022 14:49

A few extra notes: a 50A single phase supply to an EV wouldn't necessarily be a deal-breaker - you could just have the electrician spread the load to the remaining two phases, and leave one phase only for the EV. Pretty easy. But as noted, I don't think you'll actually find any >32A single phase EVs here.

Better cooling makes the battery last longer. This is especially important if you're planning to regularly charge fast and deep.

Any options for charging the battery from another battery or DC source is still going to be required to have galvanic isolation for safety reasons, which removes most of the advantages of just using a DC-DC converter. Much more expensive.

Even if your charger can't take the car to 100% within the 3 hours, it would still be mostly full. Topping up outside of that would still be minimal and fairly cheap.

And finally, don't count on that plan being around forever. Increases in time-of-use metered plans and smart/controllable loads (like EVs) means that we could see a flattening of the demand curves - certainly lines companies want to push this wherever possible. If enough people get on board with it, the price signals might be weakened.

ShockProof

31 posts

Geek

#2841486 1-Jan-2022 17:10

Thanks again, learning all the time here. I have been reading that the future is going to be liquid cooling. Forced air is not efficient anough as battery densities increase, which means hotter cells and shorter battery life. Natural air cooling seems like a bad idea altogether (e.g. Leaf as an example). I will have to just hope that the manufacturers know how to get a long life out of a liquid cooling system. Maybe for a modern cars, 8- 10 years is a full life and then it's time to get the next one. A long warranty might help as long as it includes the battery cooling.

I agree those electricity plans might not last. Powerswitch shows Electric Kiwi is the cheapest option. Pretty hard to know as we have no power bills yet for the new house, which would tell how much power is being used (not moved in yet). Powerswitch website also hasn't incorporated EV's into its model yet.

richms

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#2841501 1-Jan-2022 17:56

Dingbatt:

Edit: ref EV cost vs liquid fuel costs.

So 8 years to recover the extra cost batteries impose.

6 years if you qualify for the rebate.

5 years once ICEs get levied.

4 years once servicing costs are taken into account.

You have to want to do this for more than cost savings, but that certainly helps.

However, back to the OP. I wonder why there isn’t the option, particularly within the Tesla ecosystem to do DC charging from a Powerwall to a Car. There must be a market there, particularly if you have PV panels. Otherwise you are using an inverter to convert and then the Transformer/Rectifier in the car to convert again.

The idea that avoiding the inversion will make it more efficient is not really true, since you would be installing duplicate hardware to do DC to DC, and then have to move that from the powerwall to the car so more cabling costs etc, whereas the DC to AC and AC to DC hardware is proven, efficient, uses cabling you need to have anyway and is also more flexible in powering other things and being powered by other things. The few % that you would save by eliminating one of the conversions never pays for itself unless you were to have dedicated hardware to just EV charging and not want the other benefits of the powerwall.

Richard rich.ms

Scott3

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#2841678 1-Jan-2022 21:33

ShockProof:

Yes, already admitted that I got that wrong. There isn't a lot of information on the brochures that come on-line for the vehicles that I have been looking at. Also new to EV so still working out what is what. But it is a good surprise that over 7 kW the manufacturers are using 3-phase AC input.

My new house has 3-phase power installed and I have two five core cables in the garage walls for future EV connection points be they AC or DC.

My thoughts on a 15 - 20 kW DC car charger are blown away by a 22 kW AC charging Renault Zoe EV. Much better solution than going DC. I would only need to get a 3-ph interface installed on one of my 3-ph cables, which are 32 A rated I think (will have to ask sparky what they put in). This is called EVSE I see. It seems to be a negotiator between the available AC supply that I have and the battery charger installed in the car, and does EV metering as well, and a bit of protection service and some other nice to have stuff.

It's tricky for somebody new in the space.

A lot of information online is USA centric. They (like japan) are largely a single phase system for end users, and three phase power is rare. As such the single phase "Type 1" socket is used on cars (or the Tesla proprietary connector), which is set up to support higher single phase currents, but not three phase.

NZ nearly went down the single phase route, due the dominance of the Nissan leaf, and used import EV's from japan in the early days. But thankfully the government came out with charging guidelines (public AC charging type 2 un-tethered, and public DC charging to be duel cord CCS2 & Chademo) - Prior to this tethered type 1 & CCS1/Chademo fast charging had been the defacto standard.

Obviously this is great for OP with 3 phase power at home. A decent chunk of nicer EV's support 11kW AC charging on 3 phase (Tesla model 3, polestar 2, Kia Niro, BMW i3 (Recent NZ new) etc.

And of course the EVSE (basically just a switch that liven's the charge wires, once safety checks are compelte) for AC charging using the cars onboard charger is cheap at cira $1500, compared to a DC charger at $25k.

As a general note, many people new to EV's over-estimate the importance of fairly fast home charging:

- Very rare used cases can be handled via the public fast charging network

- For AC charging, manufactures generally quote 0% - 100% charge times (unlike DC charging where 10% to 80% is often quoted). Reality is that everybody runs a bit of a safety margin, and is unlikely to turn up at home with less than say 3% in the battery. Also most EV owners will only charge to 80% or 90%, unless they have a big trip planned the next day as this is better for battery health.

- Beyond the above, modern ev's often have have 250 - 450km ranges. Few people drive these distances daily. Most will do under 100km a day, other than for an abnormal trip. So say somebody leaves on 80%, and gets home on 60%, then tops back up to 80%.

For OP, I would suggest that 11kW is plenty, if a car other than a Zoe is seen as desirable. That will allow 120km of range to be replenishes in the 3 hour window.

Should also note that free power windows are just a marketing approach of some power companies, and are essentially paid for by higher power prices at other times. Can do well as a consumer from them by really hammering them, but if too many consumer's do so the power companies will loose money and give up that approach. Plenty of power companies do day / night plans and market to EV owners. Personally I just went with a 24/7 plan. We are home most days and the EV is a minor power used (plus the range of the leaf is so low, I take the opportunity to top off to 80% whenever I am home).

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