J
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2 Messages

Monday, November 28th, 2022 9:50 PM

Are home chargers worthwhile?

We have been driving our 2021 Nissan leaf since FEB this year, We have solar panels and a Tesla battery. We generally don't drive more than 100KM a day - mainly short trips around town. We have never had to use a public charging station.

I see a lot of advertising for home wall chargers, but so far I have not seen much benefit except the ability to use a smart phone to check charge state.

A much more important use for us would be a reasonably priced V2h device, It will be very frustrating when we have our next power failure and we can currently only use the USB dash outlet off the 12V battery.

I have seen a good looking bi-directional charger available from Thailand - see https://deltathailand.com/en/products/Infrastructure/Energy/EV-Charging/AC-Charger/V2G or https://tinyurl.com/4s2p2v7r for the short version. But the cost is greater than US$ 3000 before shipping. :-((

Where to now? All the best - JohnS in warming Canberra Springtime.

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52 Messages

2 years ago

Better to use the car as an air conditioned lifeboat with reclining seats and onboard entertainment systems during a power outage. Leave the fridge door closed, and/or buy a UPS for it. Let everything else stay offline until the power comes back.

At least you can run the car's air con in your garage, keeping the car under cover & out of the sun, without draining the starter battery or asphyxiating yourselves.

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7 Messages

2 years ago

Assuming that you are asking about an EV car battery powering your home, not all EV allow V2H. Japanese cars do, I gather because in Japan cars form part of the grid balancing strategy. So Nissan is OK. The battery would need to be quite formidable to run the house in a serious outage and justify the cost of the wall system. One issue may be how energy efficient your house is. ie what is its baseline power consumption for mission critical uses. Your solar panel management system will probably give you that data which can be matched to the car and Tesla battery capacity to see just how much bangs you will get for the bucks to be spent over and above what the Tesla battery is giving you anyway.

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@Cotman​ 

Our house is only 7 years old and super insulated with double glazed windows etc. The Tesla solar battery will power most of our needs for a day or two. But I would like to give our son a backup two stroke power generator as we have a great battery in the car. Just a shame we can't use it.

Not sure where the 2021 Nissan leaf is made - but it definitely does not do V2h or V2g.

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7 Messages

the chances of a longer than two day outage are pretty slim, so the expenditure to access the car battery, even assuming that that is possible, doesn't seem to be justifiable. your son could get both a generator and a cheque (how old fashioned of me!!) for the money not spent on a two way charger. A win/win outcome (at least on your son's side).

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2 Messages

2 years ago

Charging using a standard 10A outlet isn't optimal for utilising your solar system because you can't take full advantage of the solar energy, unless you only have a small system.  For example, say you have a 6kW solar system that generates more than 4kW over a 6 hour period of sunlight (24kWh of energy over the day).  If you are only charging at 8A (the limit for many 10Amp socket chargers) this is only 2kW going into the car's battery.  The rest of the solar power you are generating is going into the grid (at a tiny feed-in tarif) rather than charging your battery.  Only 6 x 2kW = 12kWh goes into your battery. 

However if you have a 7kW or 11kW charger installed at home, then you can set it to charge at 4kW and then you get the full 24kWh of solar energy going into your car's battery instead of back into the grid, saving you money.

Another advantage of having the 7kW or 11kW charger installed at home is the ability to charge your car from flat to full overnight.  This isn't possible when charging from a standard 10A socket. 

For more information on charging electric vehicles, see https://www.evjourney.com.au/evcharging

Happy electric motoring!

Oliver

(edited)

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2 Messages

2 years ago

Try a solar diverter charger.

100% of the feed into the grid energy is now diverted In to your car. Changing for $0.

It's slow but you don't have to buy the energy. Once your car is full it will then diverted excess energy  you make back into the grid.

Or use your cheaper off-peak power

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5 Messages

2 years ago

We have had an EVSE since late 2021.  Initially it probably wasn't all that necessary as we just had a 40kWh Nissan Leaf, but now we also have a BYD Atto 3 and the ability to get some electrons into either car when required is worth the $1800 it cost to get it installed (a Zappi so slightly more expensive that some).

Ours is only single phase (up to 7kW/32A) as we couldn't justify getting three phase installed for future proofing.

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73 Messages

@OldPhart​ Agreed. Having two EVs makes a wallbox much more useful (because now the wallbox gets double the utilisation). The main advantage of a wallbox, as I see it, is that you can leave your portable charge cord in the boot at all times, eliminating the possibility that on the day you really need it, you find you've left it behind in the garage!

I also like untethered EVSEs as you inevitably need to buy a cable anyway. On those occasions when you're going on a longer trip, you just take the same cable with you.

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3 Messages

2 years ago

Hi,  There are charges which can charge

  • only on your excess solar (ie that solar power you would otherwise export for a few cents / kWh income)
  • & if that not enought top up on Off-Peak
  • or if you need, 'rapid charge' at any time ie 32 Amps on single phase supply

I have one of these and it will pay for itself. If you travel 100km, you will likely use less than  20kWhrs of power each day. That is  probably more excess power than  available from solar power with a 5 kW inverter but close if you are not using much power in the house, so you could top up on off-peak (about1/3 the cost of peak power). Such a charger will cost you a couple of $K to install but it will definitely pay for itself & give you a feel good home 'petrol charging station. I have a Zappi charger which does this for me 'automagically'.  (Requires 6mm submain & gives a max 7 kWhr charge ie 3 hrs to charge 20 kWhr on mains power).

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5 Messages

@BernieG​ yes.  Our Zappi has three levels of charging which coincide with what you outline in your post.  Combined with a time of use tariff and solar plus battery, it is possible to minimise electricity costs.  When I'm at home I charge from Solar during the day.  We also charge at off peak times as necessary, either in the late evening or early morning.

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52 Messages

2 years ago

@JohnS ...... you originally posted this late last year, what have you done regarding getting a home charger? Did you recently go to the Fully Charged Show in Sydney? There were plenty of people to talk to and discuss with there.

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7 Messages

2 years ago

When I bought my MG ZS, I installed a 7kW wall unit. I didn't have solar, but I thought it was a good idea. I charged about twice a week.

I've just moved to an retirement village where I have access to only a 10A socket. It's changed my ideas on charging. We do, on average, 30km per day, and we plug in every day. That's about 3 hours charging per day. So, unless we were doing around 120 km per day, the standard 10A outlet will meet our needs. You get home, plug in, and when you come out in the morning  it's charged.

If you have solar, it's a different matter, as you want to get the max benefit from the sun. You'll need a hi-speed wall unit under those conditions, and one that can optimise charging from solar.

Gonzo

(edited)

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3 Messages

@gonzoB​ Hi, what you say is sensible however there is a little known problem with what you (and many others) are doing. The 'Wiring Rules' ie the 'electrician's bible', does not allow for 10 amp power points to be used as charging points for EVs. I assume this is because the constant load on that circuit (which is usually shared with other devices) will 'strain it' and if there are any weak points in the circuit potentially cause a fire in the house. No other load in your house will test the wiring power point circuits as much as this except maybe power points with space heaters on for long periods of time and if that happened to also power your EV overheating becomes more likely. You probably do not have a problem, but if such fires start to occur, you can be sure the home insurers would see this as an excuse to not pay the fire insurance policy. The 'Wiring Rules" are mandatory under Australian laws for domestic (and industrial) premises. In the mean while, EV makers still provide this option. N.B. The 'Wiring Rules' require a minimum 20 amp dedicated circuit for EV charging in an Appendix specifically  for EV charging.

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7 Messages

Thanks for that. I wasn't aware of that change to the wiring rules. It makes sense.

In my case I think the risks are low, as the charger pulls about 7.5A, and it's only charging for 3 hrs average per day. The arrangement at the retirement village is only temporary until I get a permanent parking spot, and at that point I'll get a dedicated GPO on its own circuit.

Gonzo

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3 Messages

You are probably right ... but there may be some value in just checking the temperature of all of your GPOs after a charge to see if any are warming up as an interim measure. Most GPOs are wired in a daisy chain arrangement so anyone could in the 'chain' could heat if there was a poor  connection.

BernieG

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