Home charging costs

[RedWhiteMonkey]

I'm researching the costs of a possible electric car for the work commute. It only needs to be something small and simple. If we lease something new I like the look of the Hyundai Inster or the Fiat Grande Panta. If we look to buy outright then an older VW e-up or Renault Zoe looks good.

I know this is simple maths but I am doubting myself. We already have a wall box in our parking garage and the electricity price is 10.7248 cent (I'm in Germany) a kilowatt hour, which equates to 0.107248€ per kWh. The Hyundai has a 42 kWh battery (seems approximately the standard size for this class of electric car) and our wall box charges at 10 - 11 kilowatt (I have seen this when charging my father-in-law's electric car). I calculate that as 42kWh divided by 10 kilowatt equals 4.2 hours to fully charge. Then 4.2 hours multipled by 0.107248€ equals 0.45€.

Is that correct? Seems very cheap, am I missing something?

[Pickle_Rick]

If its 0.10 euros a kwh, and the battery holds 42kwh, then the cost to charge from completely dead to 100% is 4.20. At 10kw charge it'll take about 4 hours, makes no difference to cost whether it's that or 8 hours at 5kw, unless you're on a special time of day tariff.

Realistically you'll be charging from 20%, so cost probably more like 3.40.

Edited by Pickle_Rick on Tuesday 25th November 11:43

[ChocolateFrog]

Factor in around 10% losses but it'll still be dirt cheap even if you bought the least efficient EV available.

[RedWhiteMonkey]

Thanks, much appreciated.

I now see where my calculation is wrong, not as cheap as I thought but still a lot cheaper than a tank of fuel every fortnight. Food for thought.

[ChocolateFrog]

Easier to think of it in miles covered.

Take a fairly average efficiency of 3 miles per kWh. You're using around 4 cents a mile of electric.

Cover 100 miles a week and it's €4 a week.

[gotoPzero]

The way I calculate it is add 25% on to the estimated total - to cover charging losses, vampire drain, pre heating, winter vs summer and the occasional away from home charge. IME that covers most of it.

So for example if you think you might use 2000kWh a year then budget on buying 2500 at 10 cents. That will IME be more realistic.

I have found over the years you are more likely to drive an EV than an ICE vehicle just because its so much more economical. The above helps factor some of that too.

hth

[sixor8]

In winter, I'm getting losses of 20% charging from AC alone, although I only use a 3 pin plug.

[ashenfie]

I think that if I used Octopus energy rate the gave me 7p per kw in the cheap window and 28p in the day time. It would workout quite expensive as I work at home. So I use 290kwh of electric and would only charge once a month so that is about £4.90, but pay around £15 extra for electric. so really that is £19.90.

[Evanivitch]

J4k43 said:

Get yourself a solar and battery set up. That 7p charges the battery at night should the solar not cover it.

Then again if you work from home then just don't bother and go for the cheapest electrical rate you can. It may not be Octopus.

If your going to quote usage perhaps it may be an idea to give the period and the annual car mileage you do.

Or plug your car in at 8am and say you need to leave at 11am...

[ashenfie]

J4k43 said:

Evanivitch said:

J4k43 said:

Get yourself a solar and battery set up. That 7p charges the battery at night should the solar not cover it.

Then again if you work from home then just don't bother and go for the cheapest electrical rate you can. It may not be Octopus.

If your going to quote usage perhaps it may be an idea to give the period and the annual car mileage you do.

Or plug your car in at 8am and say you need to leave at 11am...

One of the benefits of Octopus is that they often charge the car during the day and the rest of the house usage is also at that 7p rate during that period. However if someone does limited mileage that rate will not be triggered.

It seems though many do not understand how these tariffs work.

Yes these tariff are great, if you do average or over average milage. If you have high consumption of electricity during the day, because you work from home or have a family, then you need to consider the uplift in the day rate. 7p at night for EV, washing etc, but you paying a premium of the the day time use, which in you maths need adding up. So if you best normal deal is 23p and the Octopus Go rate is 28p and you charge once a month then it not really costing £4.90 to charge but £19.90, you can see upping your milage soon reduces that headline figure. Solar would help if you exported during the day and imported at night, that is something you could calculate and average over a year.

[ashenfie]

J4k43 said:

ashenfie said:

Yes these tariff are great, if you do average or over average milage. If you have high consumption of electricity during the day, because you work from home or have a family, then you need to consider the uplift in the day rate. 7p at night for EV, washing etc, but you paying a premium of the the day time use, which in you maths need adding up. So if you best normal deal is 23p and the Octopus Go rate is 28p and you charge once a month then it not really costing £4.90 to charge but £19.90, you can see upping your milage soon reduces that headline figure. Solar would help if you exported during the day and imported at night, that is something you could calculate and average over a year.

What do you call high daily consumption? I'm at home most days particularly in winter and run the computer and radio and I've worked out it's better for me to be on the cheap rate as I have solar and a 10kWhr battery. High load stuff like washing, dishwasher and tumble drier are done at night.

Well yes that is subjective. I use around 300kwh-400kwh per month that is mostly my home office stuff. Solar vs battery again really depends on use case with a decent export rate then battery has less impact. I haven't done the maths for that and will when I get a chance look at it.

[JQ]

Can't help with the calculations, but my wife had an e-Up and absolutely loved it. Drives like a go-kart and is a Tardis - very small on the outside but bigger on the inside, so could park it anywhere. It's quite a simple car with very few mod cons but that was part of the appeal.

[ashenfie]

JQ said:

Can't help with the calculations, but my wife had an e-Up and absolutely loved it. Drives like a go-kart and is a Tardis - very small on the outside but bigger on the inside, so could park it anywhere. It's quite a simple car with very few mod cons but that was part of the appeal.

Or shopping trolly, great use case thu.

[JD]

ashenfie said:

Well yes that is subjective. I use around 300kwh-400kwh per month that is mostly my home office stuff.

Must be a warm office!

My last 54 days bill was 1474kWh at average cost of 11.8p, 368 of them at peak rate.

Edited by JD on Friday 28th November 14:23