UK typical public / workplace charging costs for 7KW?

[GlasgowSi]

I've had my i3 a few months now and loving it so far - I generally just charge at home, but when I do travel into the city centre I typically charge there too as the public charging there is provided for free (currently at least).

My place of work has been working on getting charging points installed for sometime now, and finally they have announced they are ready to use. However, rather than providing them for free they have decided they will be charging for them, and using an external company (chargepoint genie) to do so. It appears that the charging points are fast 3-phase 22KW AC units, which of course the i3 can't take full advantage of (in fact as far as I can tell only the Renault Zoe and Tesla S can actually charge at 22KW?), so if I were to use them I would only be drawing 7KW (same as I do at home). They are charging £1.50/hour to use these things regardless of whether you are using 7KW or 22KW, which seems ludicrously high to me (at least for everyone stuck at 7KW). Considering it takes me around 5 hours to charge my i3 at home from near empty to full, and at a total cost of electricity of a little over £2, it strikes me that £1.50 for an hour of charging at the same rate is pointless.

I am just trying to work out what the current "going rate" is for charging at 7KW in places where it is charged, so I at least have something to suggest to the people managing the scheme!

 

[BrianStanier]

£1.50 or more seems to be typical for those that do charge.

Slightly off topic, but it should only take somewhat over 3 hours to fully charge at 7kW though it does taper down at the end.

 

[GlasgowSi]

Thanks - figured it was probably about right for public (charged) charging, but doesn't make it any more likely for me to use it at that price! Seems daft as it would end up costing as much (if not more) than petrol, when the whole point of them getting them installed is part of the company's "Low Carbon" strategy! At least I can generally get to and from work on a single charge anyway, and I have the REX for the occasions (usually very cold weather) that it isn't quite enough.

As for the time to charge, I'm not sure I've actually properly timed it, but while it starts off at 7KW it does seem to start tapering off after not too long. It certainly gets to 80% in less than 3 hours but the remainder tends to take a while extra. To be honest I've not properly monitored it as I never really need a full charge again that quickly - think I've been going by the guess-o-meter in the app for when charging would be complete, which may be way off if the Range GOM is anything to go by!

 

[BrianStanier]

It depends what state of charge you have when you start. You imply around 50% if you can do the return journey of a full charge, so an hours charge should get you up to about 80% which is below the point at which tapering starts. That hour should give you about 25 miles which corresponds to about 6p/mile. The Rex is quite efficient, but would give you about 50mpg which is around 10p/mile. So even at that hourly rate you would win.

 

[Lincsat]

Can you use the 13a OUC and hang the cable out of a window. Even if only for a "safety" top up.

 

[janner]

Chargepoint genie are SSE and do seem to be rather expensive compared to others. Looks like a bad choice by your employer.

Their public charging points charge £4 per session plus 1 unit per minute at 10p per minute of charge (3 hours = 180 minutes = £18) so a total of £22 per charge or about £1.20 per kW-hr. Looks like daylight robbery if my sums are correct.

 

[BrianStanier]

I think you're misreading the tariff. The £4 includes 4 hours of charging as I read it.

 

[janner]

Thanks for the correction. Yes, I misread it. Although my initial comment about Genie SSE being rather expensive still stands, I think?

For 7kW and 22kW chargers it's £4 per session (up to four hours) so a cost of about 21p/kW-hour for a full tank or considerably more if you already have some juice in the tank - maybe £40p/kW-hr.

For DC rapid
- £4.00 each time a charge is initiated, to include charging for up to 15 minutes.
- £0.25 for each subsequent minute.
assume 30 minutes = £3.75. So £4 + £3.75 = £7.75 or 41p/kW-hr.