Harden Electric Blog How you could save money by converting to EV

How you could save money by converting to EV

So we did a post a while back explaining how businesses could save money by converting their fleet to EV. And it was met with mixed responses, as really the biggest benefit to an EV conversion from a large scale fleet perspective is numbers, sheer raw quantity of vehicles saving money, so this doesn’t work for the average consumer.

So let’s knock it back a notch, and imagine that you have a car that you currently own, love, and suits you and your family. It’s a good car, but the engine is getting a little bit tired. It does everything that you want it to do and you don’t really need a new car, but you want to reap the benefits of going electric and doing your bit for your pocket and the environment.

Some ground rules

Now we will use the average Australian vehicle usages for the sums here, which means that the average Australian car owner travels 20-25,000kms a year in their car, going to work, going home, running to the shops and back, and doing the school runs each day.

So let’s go with the higher end here, the 25,000km mark:

25,000 ÷ 52 = 480.76km per week, so let’s just round this down a tad to 480km per week. The 760m extra isn’t really a huge deal for this math.

We are going to use an average family car for this calculation, as Australian’s, we are are going to pick something fairly standard and well known, so we will go with a VY Holden Commodore Station Wagon, which is still a fairly common car to see on the roads these days, even if their production run was 2002-2004

We’ll take the standard model with the 6 Cylinder 3.8l Petrol engine.

For the purposes of these calculations we will use the data from this Redbook page.

So let’s put some of those easy figures onto paper:

Fuel Capacity75
Fuel Consumption (Urban)11.5
Fuel Consumption (Extra Urban)7
Fuel Consumption (Calculated Average)9.25
Average Range810km
Tare Mass1,555kg
Gross Vehicle Mass2,035kg
Engine Weight178kg
Seating Capacity5
Average Passenger Weight75kg
Total Passenger Weight375kg
GVM Remaining once Passengers accounted for105kg

Ok, so from the outset you can see that this vehicle runs pretty close to it’s line with just 5 passengers in it, assuming all are adults around the 75kg mark, but really, most people will be Mum, Dad, and 2 x Children, and the average weight for a child is normally calculated at 35kg, so we could adjust this number down to 220kg instead of the estimated 375kg, a saving of 155kg

Let’s lose some weight!

Ok, so straight up, let’s get some weight back into the mix of things, knowing that the engine weighs in at 178kg we can drop that out, we will retain the gearbox for efficiency reasons, and because although some motors like Tesla’s run a single gear, it is a lot more efficient to run a gearbox even in an older car. This also gives you the ability to adjust your driving style to suit the conditions without too much hassle to the overall feel of the vehicle. The aim of the conversion is to save money, not turn the car into a weird spaceship that is strange to drive.

Now we can move onto all the fuel lines, fuel tank, and other assorted bits and pieces, we could easily assume that we will lose in the vicinity of 100kg here, that should be a good safe estimate.

Finally, it’s up to you as to whether you feel you need it, but just have a good solid think about when the last time you used your spare tyre was? If you are anything like most people I know, you know it’s there, and there’s a chance that it is either flat, or the rubber has perished and it is out of date and stuck to the inside of your wheel well. You could save 50kg there.

For now I’m going to assume that you want to keep your spare tyre and the tyre gear.

Overall weight saving: 278kg

Planning the conversion

Ok, so now we need to move forward on some planning for this. Remembering that above we gave some figures on the average distance to drive per week being 480km? This works out to a daily average of 68-96km a day depending on if it is a 7 day driver or only a weekly driver.

Now, one of the advantages of electric is that you never need to visit a petrol station ever again, that’s right, those days are gone.

So how do you charge it?

Well, if your house is anything like mine, there is a good chance that you have one of these sitting in your garage, probably stuck to the wall:

Standard Australian 10 Amp Powerpoint

Yep, you can now fill your car, at home, via a standard Australian Power Point.

So most commercially available 10 Amp Chargers like this one are 2kW chargers on a 10 Amp Circuit. So this means that every hour it is plugged in, you will charge 2kW of your battery up. This equates to approximately 12km of range per hour.

If you are lucky, instead you will have a 15 Amp Socket in your house, which can take a charger such as this one, which means that you will get around 3.6kW or 20km of range per hour.

If you are a really lucky duck, you will have 3 Phase, which is surprisingly becoming far more common in newer houses, as people want their reverse cycle split system ducted air conditioning, and a lot of these systems are now being sold to run 3 Phase 32 Amp power, as it works out ot be more efficient. So you might be able to go with a charger such as this one and get a whopping 22kW charging capacity which equates to around the 120km per hour of charging.

So, to put that in some perspective:

5 Day Driver7 Day Driver
Distance Driven Per Day (km)9668
10A Charge Time8 Hours5.6 Hours
15A Charge Time4.8 Hours3.4 Hours
32A Charge Time48 Minutes34 Minutes

Now, for the average person, consider your day and think “Is there any time, after getting home, before leaving for work in the morning, where I don’t touch the car for 8 hours?”

For most people, this answer is yes, you get home from work, you throw your feet up on the lounge, you cook dinner, spend time with the kids, and then probably go to bed where you get an average of 6-8 hours of sleep. So even in the worst possible scenario, the average person can charge their car off a standard 10A powerpoint overnight.

But won’t the cost of my electricity go up?

Well, yes. But not that much. Especially when compared to the cost of running a petrol car, which you will now be saving that money.

So the average km we are doing in a week is 480km, so if we are taking 8 hours to charge our car per night, that’s 40 hours of 2kW charging per week, or 80kWh of electricity.

So based on the average cost in each state and territory, you will look at around:

StateCost per kWhCost per week

So looking across the country, this gives us an average of $‭21.5536‬ to charge your car every week.

So how does this compare to your fuel bill?

Well, taking that same Commodore we have been looking at, we end up with:

75l of fuel ranging at 810km per tank

This works out to be ‭0.0925925925925926‬ litres of fuel per kilometre

So calculating for 480km per week that’s 44.44 litres of fuel per week

Now, using the weekly Australian Average Petrol Price Report this week, we get 120.7 c/l for the cost of fuel

So, we multiply that 44.44l by $1.207 and we get $53.64 for your weekly running costs.

So really, if the average cost to run this car on petrol is $53.64 and converting it to electric will be $21.5536 per week, that is a saving of $32.0864 per week to your household budget, or $‭1,668.4928‬ per year.

That’s right, just on petrol you are saving over $1,500 per year!

Will this save me any more money?

Well, maybe. THat depends, do you live in a state (like QLD) that charges your registration based off engine cylinders? Then yes! You now have a 1 Cylinder, 1cc engine and you will be charged in the lowest rego bracket. This means that you may save up to $500 a year on your rego, popping your savings over the $2,000 mark.

Then there is also the matter of servicing, at 25,000km a year the average car being serviced every 15,000km’s means the average owner is servicing their car 1.6 times per year, and the average cost for a service is around $450

Considering an electric motor has only a single moving part and generally only 2 bearings, that means that they essentially never need to be serviced. Even to the point where Tesla really has no fixed maintenance cycle on their vehicles, including things like Brake Pads, which are barely used in an electric car, as you can use Regenerative Braking to return energy to the battery and avoid wearing out your brake pads.

So you can look realistically, if you are in the rights state for rego, to save around the $2,500 mark per year to your household budget, or around $50 a week.

So what do I need?

So, as I said above, you have around the 278kg to play with in your conversion, so let’s put some items on the table:

Electric Motor
Net Gain HyperDrive (With Controller)
Remaining Weight223.5kg
Vehicle Interface ECU5kg
Remaining Weight218.5kg
Hydraulic Pump5kg
Remaining Weight213.5kg
Vaccum Pump (For Brakes)2.5kg
Remaining Weight211kg
Electric AC Compressor5kg
Remaining Weight206kg
DC-DC Convertor15kg
Remaining Weight191kg

So after swapping out all of the major bits, we are left with 191kg remaining, this could be as high as 241kg if you choose to forego carrying a spare tyre.

From here, we can work out our battery size, now a standard Tesla Pack weighs in at around 25kg and packs 5.3kWh so you can get 7.64 of them in there, so we’ll round that up to 8 modules for a total of 200kg putting us only 9kg over our factory weight of the car as it came standard.

At 5.3kWh per battery, these modules will give you 42.4kWh of range, and given that we are using around 80kWh a week to go 480km that means each full charge will get you 254.4km out of that capacity, so if you wanted to forego charging the car for a couple of days, you could get 2.65-3.74 days out of a single charge.

Because, here’s one beauty of it, one thing that a lot of people don’t realise is that a lot of shopping centres are starting to install electric vehicle chargers, these are DC fast chargers and they can be used to charge your car for absolutely free, as they see that if you are coming in to charge the car, then you will be spending time (and money) to go into the shops and do your shopping, maybe get a coffee, and hang around for a little while.

So this means that if you play it smart, and split up your shop into a couple of times per week, you can actually have your cake and eat it to, and get all of your mileage taken care of for free.

How’s that for an incentive? Saving you an extra $21.5536 per week, or an extra $1,120.7872 per year on your vehicle running costs.

Best case scenario, what are my savings?

So, if you are able to live in a state that charges you based on cylinders, and you can leverage free charging, then you estimated savings per year could be up to $3,700 a year including servicing and such.

Ahh, but what will it cost me?

So, taking the costs of the items mentioned above:

Electric Motor$7,150
Vehicle Interface ECU$5,000
Hydraulic Pump$1,000
Vacuum Pump$500
AC Compressor$1,500
DC-DC Convertor$1,250
Misc Parts$5,000

Now, the above quote is keeping in mind that we have specced absolutely top notch gear for all of the parts, you can probably halve that cost easily by using second hand parts, and new advances in battery technology can get the cost down for batteries, from what is above at $471/kWh to around $100/kWh which will mean the cost for batteries will come down to around $4,240 which is a saving in that aspect alone of $15,760

So, assuming your current car is in good condition and that you intend to keep it for the long term, you could feasibly pay off the conversion in around around 12 years, from then on, you are saving money easily.

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