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Charging Times
To understand how charging times come about we need to consider some basic electrical theory, as follows:
Power (Watts) = Current (Amps) x Voltage (V)
Charge Time (hours) = Battery Capacity (kWh) / Power (kW)
In a three-phase system the power is simply three times the single-phase power. In Europe the Voltage is the standard supply voltage of 230V – this is true for our purposes whether it’s a domestic single-phase supply (as used in the home) or the phase voltage of a commercial three-phase supply (as used in a public fast charge station).
The nominal battery capacity of the Zoe is 22kW. Using the various power options gives us a table as follows:
CHARGING TYPE
PHASES
CURRENT (A)
VOLTAGE (V)
POWER (KW)
CHARGE TIME (HOURS)
Domestic socket 1 10 230 2.3 9.5
Wall charger - standard 1 16 230 3.7 6.0
Wall charger - high power 1 32 230 7.4 3.0
Fast charger 3 32 230 22 1.0
Quick charger 3 63 230 43 0.5
Some points to note:
All values are approximate.
All systems are assumed perfect, in fact power loss in the charging process means that charge times will be longer than these theoretical values, by perhaps 10%.
The fast charge time of half an hour is for about 80% capacity, as discussed above, because the charging process must slow down as the battery fills up.
Charging Times
To understand how charging times come about we need to consider some basic electrical theory, as follows:
Power (Watts) = Current (Amps) x Voltage (V)
Charge Time (hours) = Battery Capacity (kWh) / Power (kW)
In a three-phase system the power is simply three times the single-phase power. In Europe the Voltage is the standard supply voltage of 230V – this is true for our purposes whether it’s a domestic single-phase supply (as used in the home) or the phase voltage of a commercial three-phase supply (as used in a public fast charge station).
The nominal battery capacity of the Zoe is 22kW. Using the various power options gives us a table as follows:
CHARGING TYPE
PHASES
CURRENT (A)
VOLTAGE (V)
POWER (KW)
CHARGE TIME (HOURS)
Domestic socket 1 10 230 2.3 9.5
Wall charger - standard 1 16 230 3.7 6.0
Wall charger - high power 1 32 230 7.4 3.0
Fast charger 3 32 230 22 1.0
Quick charger 3 63 230 43 0.5
Some points to note:
All values are approximate.
All systems are assumed perfect, in fact power loss in the charging process means that charge times will be longer than these theoretical values, by perhaps 10%.
The fast charge time of half an hour is for about 80% capacity, as discussed above, because the charging process must slow down as the battery fills up.
You could buy a meter to give you a more accurate idea of what you're consuming. BMWi installed one alongside my 32A charger which is a Iskraemeco ME372 meter but you can get simpler ones fairly cheap (I've seen them for £35 on Ebay).
I watched my consumption for the first few weeks just to see how the losses varied, you can soon see that it's fairly stable even with pre-heating. I'm averaging 16% losses which means a full charge of the 18.8kWh i3 battery costs me 94p on the cheap overnight tariff.
I watched my consumption for the first few weeks just to see how the losses varied, you can soon see that it's fairly stable even with pre-heating. I'm averaging 16% losses which means a full charge of the 18.8kWh i3 battery costs me 94p on the cheap overnight tariff.
Typically E7 tariffs are only worth it if you use 40% or more of your consumption overnight so if you can remember to stick your tumble dryer, dishwasher and washing machine on as well as the car, you might save money.
Old fashioned E7 doesn't always account for GMT either so be aware you'll need to stay up to 1am or buy timers to set everything off to get the best rates.
If you want to know the consumption, try British gas as they're installing smart meters along with a time of use tariff and you'll actually be able to see what you're paying when charging.
If you do time of use via a smart meter, if it isn't saving you more money than a single rate, they'll be able to remotely change your tariff to a single rate one again without having to swap out the meter again.
Old fashioned E7 doesn't always account for GMT either so be aware you'll need to stay up to 1am or buy timers to set everything off to get the best rates.
If you want to know the consumption, try British gas as they're installing smart meters along with a time of use tariff and you'll actually be able to see what you're paying when charging.
If you do time of use via a smart meter, if it isn't saving you more money than a single rate, they'll be able to remotely change your tariff to a single rate one again without having to swap out the meter again.
If you shop around suppliers you should be able to get that 7p down to 5p!
Bear in mind you need to factor Day time, Night time and standing charge.
Best done in a spreadsheet and play around with your expected usage and the suppliers std chg, off peak and peak all lined up woth a total figure on the right.
Good starting point for an EV owner is about 3,500kWh years peak and the same again off peak.
That's the close to average annual domestic consumption plus an EV doing 12,000 miles a year at 0.3kWh/mile.
Stick our own numbers in if you have better figures from your current bills, and a car that you have or can find online from owners comments in forums.
E.g. My i3 is averaging 3.6miles/kWh or 0.27kWh/mile. Depending on which way you prefer it.
Bear in mind you need to factor Day time, Night time and standing charge.
Best done in a spreadsheet and play around with your expected usage and the suppliers std chg, off peak and peak all lined up woth a total figure on the right.
Good starting point for an EV owner is about 3,500kWh years peak and the same again off peak.
That's the close to average annual domestic consumption plus an EV doing 12,000 miles a year at 0.3kWh/mile.
Stick our own numbers in if you have better figures from your current bills, and a car that you have or can find online from owners comments in forums.
E.g. My i3 is averaging 3.6miles/kWh or 0.27kWh/mile. Depending on which way you prefer it.
stewjohnst said:
Old fashioned E7 doesn't always account for GMT either so be aware you'll need to stay up to 1am or buy timers to set everything off to get the best rates.
I believe it does. It uses a code hidden in the Radio 4 LW signal. When I had it it was 1am-8am, shown on a little sticker on the meter.Rostfritt said:
I believe it does. It uses a code hidden in the Radio 4 LW signal. When I had it it was 1am-8am, shown on a little sticker on the meter.
Depends if you have a set up with a timeswitch (no gmt adjust) or a radio teleswitch (that uses Radio 4 signal).One of the more boring problems we have in the utilities industry is what to do about all those teleswitch meter when analogue radio dies and takes the signal with it...
stewjohnst said:
Depends if you have a set up with a timeswitch (no gmt adjust) or a radio teleswitch (that uses Radio 4 signal).
One of the more boring problems we have in the utilities industry is what to do about all those teleswitch meter when analogue radio dies and takes the signal with it...
Specifically when (if) Radio 4 Long Wave on 198kHz dies: the transmitter for that is apparently on borrowed time, it goes through a particular type of valve (metre high jobbies!) at a rate of about 1-ish per year. Fewer than ten of those left in the world...One of the more boring problems we have in the utilities industry is what to do about all those teleswitch meter when analogue radio dies and takes the signal with it...
blueacid said:
Specifically when (if) Radio 4 Long Wave on 198kHz dies: the transmitter for that is apparently on borrowed time, it goes through a particular type of valve (metre high jobbies!) at a rate of about 1-ish per year. Fewer than ten of those left in the world...
I read an article on that a few years ago saying 10 left, I wonder if that has gone down. Quite interesting as the transmitter has been going for years and covers a huge area, I once picked it up in Gdansk! Still it will one day cease, probably without warning or fanfare, either in the middle of the night or right in the middle of a test match special.I guess these will eventually have to be replaced with smart meters. Or they will just be stuck on whatever time they were on when the signal left and will slowly drift out, like the clocks on everybody's VCRs did when analogue switched off.
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