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Price of charging

OK, having been on here a while, I have noticed there are alot of clever people who can work out things quite easily.

Now I have had the car for a week and now and the geek is coming out. I have produced a spreadsheet to record charges, distances and a cost per mile.

So my question is this.

How can I work out how much a charge is costing?

What info do I need to get this?

Best way for a true geek is a power meter - this one is good.

Failing that, the charger takes about 2200 watts on my meter until it reaches 93% charge, and puts in about 360 watt-hours in the last half hour before it shuts down. I’m currently using about 150 wall watt hours to the mile since the weather started to get colder. Most of the summer it was more like 125-135 wall watt hours. Hope this helps - let us all know your consumption figures when you work them out.

Ecofunkytravel has the answer, but for those who are tight then look at your electric bill and see what tariff you are on. So lets say you pay 13p a KW
3 hours at 2200 = 85.8p
Plus the last 30 mins so less than £1 for a full charge.

It is quoted that it takes 8KWh to full charge the 7KWh battery taking 3.5 hours. So that would be 8 * 13 = 104p Call it £ a charge from flat.

As pointed out before the battery does not even get fully depleted as some is held in reserve to protect the battery, The last 30 mins is an equalizing charge and is at a lower rate. Also there are different tariffs on offer.

Also if the cooling fan does not cut out then there is an additional small cost for this. 27W for 10hrs is another 4p of over run.

If on the other hand you are really tight you will already have a power meter and checking everything in the house to save money on the leccy bill.:slight_smile:
I have one but used to make sure I don’t over load electric points on campsites. Mine came from Lidl when they have them in.

Was told about £1 by Renault-looks like they got an answer right!

They wouldn’t have known, must have read the site before you got your car. :lol:
It’s been mentioned before.

I’m bearing a strong resemblance to a guinea pig 8-|

OK my plug from ebay has come so now I can see the true cost.

53p but that was charging from 39%

Based on what I have recorded so far, its costing me 2p per mile. :mrgreen:

Thanks for taking the time to do this. Can I ask at what rate per KW/h you calculated this at?

It is worked out at 12.62p with Southern Electric.

Here is my geeky graphs so far. Just so you know my distances per charge are low due to me not having the guts to take that third trip, which i think might take me to one bar or less.

Also charge costs are on average charging 2 thirds of the battery.

You might find it interestng.

Superb data. I will start collecting mine too. One or two questions. Cost per Charge (units are probably Pounds) Can you confirm? And that would make Cost Per mile in Pounds as well?? Electricity Cost per KW could be a good legend so we can compare. You said 12.62?

No Units are pence. Its 12.62P

Otherwise its £2 a mile :o

Of course I could be wrong.

The cost per charge must be in £ (pounds) while the per mile is shown as Pence. 60p (Shown as 0.6 pounds) to charge does 30 miles so works out as 2p (0.02 pounds) a mile.

This all matches the calcs we did at the starts to get £1.04 a full charge. ie 50 miles.

So am I wrong?

Not at all. Just the Y Axis states Miles and perhaps should be units. Your graphs are great, wish I had the patience to record it.


OK. I just got the results of my first metered re-charge and although it was only from 63% - 99% at least its more data.

Our elect cost? I used the secondary tariff since we would use the first 160kWh of expensive electricity even if we didnt have Twizy so our secondary unit cost is 10.354p/kWh (Scottish Power. Heavily negotiated)

Distance covered = 13.3 miles
Temperature = 10 Deg C
Battery remaining = 63%
Theoretical Range = 36.9 miles (no attempt to drive gently then)
Total Power to charge to 99% = 2.3 kWh
Price to charge @ 10.354p/kWh = 23.81 p
Effective cost per mile = 1.79p/mile
Effective Cost for full recharge = 66.15p

Charge Details
Time Zero (start)
Battery 63%
Power = 9.27 amps / 2.209 - 2.216 kW modulated charge

Time = 38 mins
Battery = 83%
Power = 2.190 - 2.200 kW

Time 65 mins
Battery = 96%
Power = 3.65 amps

Time 85 mins
Battery = 99%
Power = 1.55 amps

If you add the battery lease to that of 6000 miles p.a. and £40/month (VAT reclaimed) : 8p/mile

Twizy cost me 9.79 p/mile
Petrol equivalent (@ 1.42p/litre or 4.5461 ltres/gal = £6.4555 / gall
Equals 65.94 mile per gallon

So the direct running costs do not represent a fantastic saving over a frugal small car BUT

I am not emitting as much noise
I am not stinking out the highway as much
I am not damaging the highway as much


Unfortunately, perhaps you should however factor in the additional insurance costs over a normal small car (expensive to insure) as well which would make the figures worse again and in addition the majority of us have to pay V.A.T. and are therefore paying about £49 per month. Then there is of course, the additional depreciation of a second vehicle. If it is a second car then it is simply cheaper not to purchase it in the first place and instead use the first car for the additional miles. Sadly doesn’t make financial sense but as you state the key feature is the ability to park almost anywhere which could be extremely timesaving and convenient in the right circumstances. I am sure that it could also be fun to drive. Still waiting for mine, i’ll let you know my thoughts on this aspect if it ever gets delivered.

I have seen a few references to “expensive to insure” and certainly my first attempts to get a quote through Renault Special Electric Vehicle “we know all about ZE” Insurance Services" produced some silly quotes around £350 even with my 40 year NCB etc etc. I pushed Privilege and eventually ended up at £156 with 250 excess which is about average for my risk ;). So cheap there. And as you say, I didnt buy it to save money. I bought it to have immense fun and convenience and for nipping in to town and back and forth across the New Forest.

Yep, I was getting a bit hung up on the financial side of it, but now I simply don’t care.

The cost savings are largely irrelevant (we get the use of an extra car for free which is really handy)-I just now prefer using it to anything else and enjoy it.
It has bought me a great deal more joy than misery and that is worth ££££££.

Sometimes we can rationalise things too much :wink: