Cost of running an EV

what is your nightsaver electricity rate?

On the road charging is expensive. You wont save money there.

The savings are in home charging which is typically 90%+ of your charging but, of course, YMMV.

Also, once you get an EV you also get a day/night electricity tariff so you pay <10c/kWh, not the 22c you mention. You pay an extra 2c for your day rate and an extra ~€70 on standing charge but you still save money overall... which is directly proportional to the amount of miles you drive.

So, that begs the question.... will you be charging it at home each week?

How many km's per year will you be driving?

How many unit of electricity do you use per year right now?

We can tell you exactly what you will save then even with the higher day rate.

I wouldn't be so quick to dismiss night rate because of the increase in day rate. The "payback" ratio for the increased day rate (and standing charge) of a day/night meter is somewhere in the region of 20% to 30% of your electricity on night rate.

With very little effort (i.e. just setting timers on dishwasher and clothes machine to come on at 630am), we moved about 20% of our usage to night rate. Then we got EV, which solely charges at night. That's brought us to about 55% night rate usage. So even with the more expensive day rate, we are significantly better off.

And that's for a house that is full all day. I wfh, my wife is a stay at home mum and 2 kids not in creche. (eldest goes to ECCE for 3 hours in the morning is all). So plenty of daytime usage too.

My night rate is ~10c/kWh. so full charge of 77kWh battery is indeed €7.70 so dealer isn't miles off. I've done about 3000km so far in my Ioniq 5, charging at home over night, and with a small bit of free public charging here and there (Lidl, Public Parks etc). Total cost about €60. So definitely still in the honeymoon period cost wise!

I do agree that the taxes will change at some point, can't be just the VAT on electricity and a flat €120 motor tax forever. In terms of efficiency for "moving things", an electrical drivetrain is far more efficient than an ICE at getting the power from the fuel transferred into motion.

Something I don't see discussed much is that your 77 kWh car will generally keep 30% of the battery in reserve to preserve its life, so the 350 km range is being generated with only 70% of its capacity. 77 * 70% * 2 = approx 108 kWh. At night-time rates of, say, ~12c/kWh that will only cost you €13 to get your 700 km range. Using expensive street charging gets you to €48 which is a reasonable saving over diesel but not outstanding.

(The downside of this is that as your battery's capacity deteriorates over time, a drop from 100% to 80% capacity will reduce the useful capacity from 70% to 50%, which reduces your range from 350 km to 250 km, rather than the 280 km you might have expected.)

On the day/night rate, we switched when we got our EV but when I did the calculations, we should have switched years ago -- even without the EV, our usage pattern meant it saved us almost 20% on each bill. Your mileage may vary, of course.

Thats way off unless there is some EV out there that does that.

Some examples...

Gen 1 Leaf.... 24kWh battery and 22kWh usable

ID.3... 62kWh battery and 58kWh usable

The above is all very typical for any EV I've seen, so more like 5-10% is hidden from you, not 30%.

This calculation is way off too. Regardless of whether the hidden amount is 5% or 30% you dont get to use that hidden amount so you dont have to charge it either, so its not costing you money. You seem to be adding the hidden buffer into the charging costs... thats not how it works unless I'm missing your point?

If you car has 58kWh usable and has a WLTP range of 400km's then 58kWh is all you have to charge the car with to go from 0-100% (there will be ~5% charging losses through heat). Basically, you dont use the total battery capacity figure to calculate your charging cost. You only use the usable capacity (plus charging losses).

Some assumptions I need to make here to calculate the figures so you can rework the calculations if you wish but it should still be reasonably accurate

Diesel: €1.90/l and assuming an average of 6l/100km (seems about right for your 700km's for €70)

Electricity: 22c/11c (day/night) and assuming all your charging is at home at 11c/kWh.

EV: Assuming an average of 20kWh/100km (including charging losses). Its hard to give an accurate figure here as it depends on whether you do alot of motorway driving or not but its a good ballpark figure to use as a yearly average (possibly even too high).

So, for your 24k km's...

Diesel: 1440 litres @ €1.90/lt = €2736

EV: 4800kWh's @ 11c = €528

Savings: ~€2200/yr!!!! The modest increased standing charge becomes irrelevant and your are still getting all your daytime electricity at 22c (what you are already paying).

So, your electricity bill (excluding levys) is currently €467. That will go to ~€1k but you will then also have the option of shifting some of your existing appliances/usage to the cheaper rate by turning on dryers/washer etc between 6-8am so it will bring you additional savings on top of the €2200.

No, if you're changing anyway, and you get the right electricity rates, you'll save a lot of money.

Yup... you can either do it on the charger end, or on the car end. I have the car set to only start at 2am and set a limit of +30% etc...

My wife has a PHEV (Cupra) and can also do the same within the car menus

Edit: looks like my rate is 5.25/kwh for those hours

Except it doesn’t work for the ID range. So we use the charger ;)

Oops 16.07c not €16.07🙄

Fair enough. My 2017 Outlander does indeed do that - it has a 13.8 kWh battery but my nightly charge (with the car showing 0%) is typically 9 kWh, which is actually a bit less than 70% of the nominal capacity; the battery is over four years old now so is slightly diminished. From new, it was around 9.5 kWh to charge from empty, as measured on a Zappi.

No doubt battery management is improved on newer EVs with larger batteries. You mentioned 22 of 24 kWh usable with a Gen 1 Leaf; some Googling suggested an early e-Golf gets about 20 kWh usable on a 24 kWh battery. (Maybe someone with a suitable charger could post some real-world figures for a modern EV with a larger battery size, fully charging from as close to empty as you dare and comparing that to the official battery capacity.)

That was actually the point I was making. It shouldn't take 77 kWh to charge a battery rated at 77 kWh gross because it should never be fully discharged; the rated mileage takes this into account. So, I was reducing the energy needed to 70% of that, to reflect 30% of it being kept in reserve. If only 15% is kept in reserve, then it would be 77 * 85% * 2 = 130 kWh of energy to fully charge the battery twice (to reach 700 km of range). That would increase the charging cost at night rates from €13 to €15, which is about €7.50 for each full charge.

I think the confusion is whether quoted battery sizes are gross capacity or usable capacity. All the figures I've seen are gross capacity (because it makes them sound bigger) but maybe this practise has changed more recently.

Yes. The meter is installed, owned and read by ESB Networks and they feed the meter readings back to the suppliers. You can change to anyone you like in the future. Basically your electricity supply company just bills you, they don't have any other impact on you so you can pick any of them you like.

Those Bord Gais 324h rates, assuming they include the 30% discount, are still much higher than Energia by the way.

You also need to factor in the repayments cost to buy the EV vs whatever repayments (if any) you had to make on your old car.

That could be a significant running cost that would wipe out any fuel savings vs ICE.

The substantial day/night differential is not going to exist forever. It's there at the moment as there's excess on the esb networks at night time, so it makes sense to discount and encourage.

But................ once we have all these heat pumps and EVs and God knows what else charging/ running at night time, logic has to be that this differential will shrink.

Well no.

You wouldn't if you already owned the car you were getting rid of. (Ie no debt hence no repayment)

Also in another example your repayments might have been €300 pm, they now might be €400pm with a more expensive EV. Thats a running cost.

So someone else is paying for your free fuel. How long can that last?