Thanks Granny, but we need better at home EV charging

Electric vehicles are still a relatively small section of the total vehicle fleet, and notwithstanding some bumps along the way, it’s pretty clear that the proportion of them on the road and in our garages will become much larger of the next few years.

A new or prospective EV owner will inevitably be confronted with the challenge of how do they charge their car. 

ICE vehicle owners probably haven’t worried about it much as for decades you could go to pretty much any petrol station and the forecourt would work pretty much the same way for a reasonably similar price to the one around the corner. 

EV charging infrastructure is still developing, and like any maturing technology it comes with a learning curve.  The different suite of plug types, charging speeds and costs, AC vs DC charging, not to mention the bewildering and dysfunctional array of apps you might use can be intimidating. 

While away from home charging infrastructure is getting better, for many users the ability to charge at home is a key advantage that makes EV ownership attractive for both cost and convenience.   As we move out of the early adopter phase of EV ownership I’d like us to have a better conversation about home charging .

Follow any EV forum or user group and charging questions will be prominent, and the advice you will get will be hugely varied, particularly regarding the ubiquitous ‘granny charger.’ 

This is the charger that probably came with your car (unless you have a recent Tesla) and will charge your car from pretty much any power point if you are prepared to wait long enough. 

At the typical   8-10 amps they can maintain you will probably take 20-40 hours to charge your car.  As  you will no doubt be told by any EV veteran most people drive less than 50 km a day so as long as you top up your car regularly for a few hours the slow charging wont be a problem. 

Plenty of users will tell you they have a great experience with just using their granny charger and it’s all they use and therefore it’s all you need.  Why spend more when you don’t have to?

I would counter by saying you can exist fine drinking instant coffee, but there are so many more appealing options you should consider and who wants to settle for just getting by!  Early adopters might be willing to put up with tinkering and compromise, but as we move to the mainstream we should be encouraging options that will be more suitable.   

I’d like to suggest three reasons that we should be encouraging EV users who charge at home to strongly consider making investment in a hardwired AC charger rather than making do with the trickle charger that came with the car.

Safety

It’s easy to get distracted by the nonsense spread about EV and lithium battery safety but some things are true:  firstly an EV stores a lot of energy and anything that stores a lot of energy can be destructive if that energy is released in an uncontrolled way so best to avoid it happening in the first place, and secondly, electrical safety isn’t a joke. 

That new EV is going to be largest consumer of power in your house, and it’s safe because lots of smart people have designed it carefully and intentionally.  

A charging EV is a stress test for your house and will find the week spots in old or undersized wiring, overloaded circuits and power points.  A burned out power point or tripped circuit probably won’t cause you harm, but it’s not an acceptable solution for the masses.  

A granny charger also makes it easier to make bad choices.  Think using an extension cord or a power board or bargain charger your bought online to save a few bucks.  A recent EV fire was caused by a charger using an international travel adaptor and extension cord .

It’s easy to shake our heads but most people are not electricians or electrical engineers and have limited capability to make safe electrical choices beyond ‘plug it in’ and ‘turn it on,’ so we should be designing in the safer outcome, rather than hoping that people will choose the safer option. 

A hardwired charger installed according to the Australian standard by a licensed electrician is safer solution and we should be encouraging it be to be default option.  It wont always be a suitable option (eg renters) but we should encourage people to keep the granny charger as the backup.

Convenience and cost

Most cars in Australia travel less than 50km per day and that granny charger could supply that easily in about 4-5 hours while you sleep.  However, being able to charge faster has lots of advantages.  Don’t you occasionally take longer trips so don’t you want to be able to charge quickly sometimes? 

Electricity tariffs are increasingly moving to variable rates where electricity cost can  be very cheap or very expensive depending on when you charge.  You can get special EV only tariffs with extremely cheap, sometimes free, electricity for a few hours a day.

You want to be able to charge as much as possible when power is cheap and avoid charging when power is expensive.  About 1/3 of Australian homes have solar panels on the roof and putting the excess power from them into your car is one of the best ways maximise your savings. 

A lot of home AC chargers have quite a few smart features such as charging only off solar excess or timers to utilise cheaper tariffs. Most people want to use a car to get places, not have another item they need to add to the list of things in their life that needs actively managing, so a faster and more intelligent at home charger is a good thing for most people.  

Environment

Not everyone buys an EV for purely environmental reasons, but it’s a consideration for lots of us.  We are on a journey but the reality in Australia is that the emission intensity of our power supply varies throughout the day. 

It’s much lower during the day when we have a lot of solar and wind and a lot higher at night when coal is still the dominant power source.  This will change slowly, but will be the situation for the next decade or so. 

Cheap power rates overnight are largely driven by coal power stations that need to remain operating, so if you are charging overnight you are doing so at time of maximum carbon emissions.  If you prioritise charging during the day then you can achieve a greater reduction in your GHG impact. 

I’m pragmatic here and most of us will charge when we need to fit our needs, but using a relatively fast AC home charger compared to a granny charger allows you to do more of your charging during the daytime and utilise low emissions electricity sources compared to overnight.

Summarising, as EV become mainstream it won’t just be the committed and passionate who will buy them. 

For those of us who charge at home we should be encouraging the installation of faster, dedicated EV charging points at home and make that the default for most people, keeping the portable granny charger as the backup when travelling or for those who are renting or otherwise limited in what they can install. 

The slightly extra upfront cost will be worth it.  After all, you can get by drinking instant coffee, but do you really want to?

Andrew Whitson took the plunge into EV ownership in early 2024.  When he bought his car the nearest public charger was 30 minutes drive away so having dependable home charging was a priority.  He writes from the Lake Macquarie region of NSW.