Twin electric car chargers – pointless?
Discussion
I’ve been looking into getting a twin charging point fitted, as given time, its likely we will have two cars that need plugging in.
However, it seems a bit of a minefield.
The gold plated solution seems to be 22kw dual charger and a 3 phase electricity supply. Which is about £1.8K for the charger + in the region of £5K moving the house to 3 phase. Which doesn’t sound very compelling.
A single phase 7kw chargers are more sensible money but when both cars are plugged in, your pretty much granny charging.
So would I be better off just getting a single charging point and an external socket fitted and granny charging the second car?
Plus, which of the 101 charging brands should I buy (I can’t have one which uses the mobile network as I live in a mobile blackspot).
However, it seems a bit of a minefield.
The gold plated solution seems to be 22kw dual charger and a 3 phase electricity supply. Which is about £1.8K for the charger + in the region of £5K moving the house to 3 phase. Which doesn’t sound very compelling.
A single phase 7kw chargers are more sensible money but when both cars are plugged in, your pretty much granny charging.
So would I be better off just getting a single charging point and an external socket fitted and granny charging the second car?
Plus, which of the 101 charging brands should I buy (I can’t have one which uses the mobile network as I live in a mobile blackspot).
I was doing a lot of miles when I got the EV and basically overspecced everything.
It's best to look at your use case I'd say. How many miles do both cars do combined per day? And what is the maximum?
Depending on the car and driving, 7kwh will roughly take you 20 miles. So a 12h night (20:00 to 8:00) will give you 240 miles at 7kw.
If you do that sort of miles multiple days in a row, you need a heavier setup. If not, it's a bit of a moot point.
7kw will be plenty for most households, and I'd definitely wouldn't invest in a heavier line that you don't really need if it's 5 000 quid to upgrade.
It's best to look at your use case I'd say. How many miles do both cars do combined per day? And what is the maximum?
Depending on the car and driving, 7kwh will roughly take you 20 miles. So a 12h night (20:00 to 8:00) will give you 240 miles at 7kw.
If you do that sort of miles multiple days in a row, you need a heavier setup. If not, it's a bit of a moot point.
7kw will be plenty for most households, and I'd definitely wouldn't invest in a heavier line that you don't really need if it's 5 000 quid to upgrade.
Another thing to note though, there's some definite loss in charging. With AC charging, often the in-car converter has his peak efficiency close to designed load. The other part is that a battery is better at a certain temperature to charge, so if you charge longer, it needs to maintain that temperature for longer, again being inefficient.
In other words, if you have two cars that both need 20kwh, you're probably much better off to each have them get 7kw for 3 hours rather than both 6h of 3,5kw.
In other words, if you have two cars that both need 20kwh, you're probably much better off to each have them get 7kw for 3 hours rather than both 6h of 3,5kw.
ZesPak said:
Another thing to note though, there's some definite loss in charging. With AC charging, often the in-car converter has his peak efficiency close to designed load. The other part is that a battery is better at a certain temperature to charge, so if you charge longer, it needs to maintain that temperature for longer, again being inefficient.
In other words, if you have two cars that both need 20kwh, you're probably much better off to each have them get 7kw for 3 hours rather than both 6h of 3,5kw.
Some truth in that, but I don't relish getting out of bed at 4 AM to move the charger to the other car.In other words, if you have two cars that both need 20kwh, you're probably much better off to each have them get 7kw for 3 hours rather than both 6h of 3,5kw.
As said up-thread, work out your routine for miles driven and look at the options.
Unless you're both doing hundreds of miles a week, I can't see it being a real problem.
Worst case, you get caught out once in a blue moon and have to pay for some 'away' charging.
That would need to happen a lot before an expensive solution made sense.
OutInTheShed said:
Some truth in that, but I don't relish getting out of bed at 4 AM to move the charger to the other car.
I was more alluding to the fact that he said two 7kw chargers would in essence be the same as granny charging if plugging them both in at the same time.With two 7kw chargers, he could program them to do so and just have both cars plugged in. The difference in loss I've found on various source can be nearly 5%, which is too much to ignore imho.
The other thing is, I notice that a lot of the time if I plug in my car at 18:00 coming home, it's done charging before I go to bed.
Over time I've ended up with 2 chargers at home, we have 3 EVs so it's not entirely daft. One is a dumb sort that'll just charge anything if plugged into it (so control falls to the vehicle). The other is a Zappi, which can be controlled.
We don't often charge using both, but sometimes it does come in handy, and we can either do both at once (15kW) overnight isn't any bother really, or we stagger them, so one is 23:30 to 02:30 and the other 03:00 to 05:30 sort of thing, so 8kW max. Saves getting up in the middle of the night to change them over.
And no, only single phase mains, no need for 3 phase.
We don't often charge using both, but sometimes it does come in handy, and we can either do both at once (15kW) overnight isn't any bother really, or we stagger them, so one is 23:30 to 02:30 and the other 03:00 to 05:30 sort of thing, so 8kW max. Saves getting up in the middle of the night to change them over.
And no, only single phase mains, no need for 3 phase.
steven said:
I’ve been looking into getting a twin charging point fitted, as given time, its likely we will have two cars that need plugging in.
However, it seems a bit of a minefield.
The gold plated solution seems to be 22kw dual charger and a 3 phase electricity supply. Which is about £1.8K for the charger + in the region of £5K moving the house to 3 phase. Which doesn’t sound very compelling.
A single phase 7kw chargers are more sensible money but when both cars are plugged in, your pretty much granny charging.
So would I be better off just getting a single charging point and an external socket fitted and granny charging the second car?
Plus, which of the 101 charging brands should I buy (I can’t have one which uses the mobile network as I live in a mobile blackspot).
It can be desirable but not wholly necessary to go to great lengths.However, it seems a bit of a minefield.
The gold plated solution seems to be 22kw dual charger and a 3 phase electricity supply. Which is about £1.8K for the charger + in the region of £5K moving the house to 3 phase. Which doesn’t sound very compelling.
A single phase 7kw chargers are more sensible money but when both cars are plugged in, your pretty much granny charging.
So would I be better off just getting a single charging point and an external socket fitted and granny charging the second car?
Plus, which of the 101 charging brands should I buy (I can’t have one which uses the mobile network as I live in a mobile blackspot).
If you take a charger like Zappi (and no doubt others) which will communicate if installed in multiples, you can group the chargers and set an import limit across them, negating any need to care about which car gets charge when. Just plug them both in and let the chargers balance the charging currents to stay within prescribed import limits.
This won't increase your capacity to charge but it does take the hassle out of swapping cables or car charging schedules.
I went for the whole 3-phase upgrade personally because it suited my situation, and I saw it as a future-proofing measure. I do charge two cars simultaneously regularly, and now 48kWh of house batteries too. It's nice to be able to do all that comfortably within DNO approved limits and all within a time-limited off-peak charging period.
Second charger requires DNO approva but is an option giving the full 7kw to both cars
You can set up 2x 7kw chargers sharing a 7kw supply. Depending on how you do it they’ll automatically share the supply, Tesla v3 wall chargers do it out the box, others may too, While it’s still limited it will automatically make the most of a 7kw supply.
You can set up 2x 7kw chargers sharing a 7kw supply. Depending on how you do it they’ll automatically share the supply, Tesla v3 wall chargers do it out the box, others may too, While it’s still limited it will automatically make the most of a 7kw supply.
kambites said:
If you get a two-port 7kW charger, presumably when one car finishes charging it will supply the other with 7kW? In which case unless you actually need more total energy than can be topped up at 7kW, it should be fine.
That’s correct, unless both cars have exactly the same time left to their charge limit, they are a decent solution, as one tapers off, the other ramps up, the same as the multi-charger installations on many private networks, they are capped at a group maximum demand.Do you own even 1x EV yet?
What is your daily mileage?
What is your other halves daily mileage?
I suspect you are overthinking it. We have 2x EV’s and one charger, and it’s not in use every night. With a 64kWh and a 77kWh, I charge roughly weekly and my wife less than that.
Your choice of EV(‘s) will be more important than chargers - even with two wonderful chargers, choosing 2x EV’s that absolutely have to be charged every single night doesn’t sound like much fun. The slightest emergency would cause you a lot of pain.
What is your daily mileage?
What is your other halves daily mileage?
I suspect you are overthinking it. We have 2x EV’s and one charger, and it’s not in use every night. With a 64kWh and a 77kWh, I charge roughly weekly and my wife less than that.
Your choice of EV(‘s) will be more important than chargers - even with two wonderful chargers, choosing 2x EV’s that absolutely have to be charged every single night doesn’t sound like much fun. The slightest emergency would cause you a lot of pain.
We've got 2 x 7kW chargers which can both charge at 7kW at the same time. Not very often that we've needed both cars charging fully at the same time, but has come in handy a few times. Wednesday night was the last example, 53kWh into one car and 41kWh into the other overnight. Both plugged in about 9pm on Wed and both fully charged by 7am the following morning as per usual Ovo Anytime schedule.
If both chargers are running that could be 2x7kwh which is 62a so basically 2 32 spurs would be required realistically being a 3 phase supply would be required.
Changes to the standards are coming making 100a circuits more usable and safe. While it’s partly there, the upgraded consumer unit are not available until next year. Notably Scotland are no following the standard, opting for another route (great!!)
Anyway if you really want two then maybe wait while the standards get sorted.
Changes to the standards are coming making 100a circuits more usable and safe. While it’s partly there, the upgraded consumer unit are not available until next year. Notably Scotland are no following the standard, opting for another route (great!!)
Anyway if you really want two then maybe wait while the standards get sorted.
ashenfie said:
If both chargers are running that could be 2x7kwh which is 62a so basically 2 32 spurs would be required realistically being a 3 phase supply would be required.
Changes to the standards are coming making 100a circuits more usable and safe. While it’s partly there, the upgraded consumer unit are not available until next year. Notably Scotland are no following the standard, opting for another route (great!!)
Anyway if you really want two then maybe wait while the standards get sorted.
Ours seems to work ok and we’re only on 100A not 3 phase. Changes to the standards are coming making 100a circuits more usable and safe. While it’s partly there, the upgraded consumer unit are not available until next year. Notably Scotland are no following the standard, opting for another route (great!!)
Anyway if you really want two then maybe wait while the standards get sorted.
I wonder if the OP will come back to actually give some useful information?
It's a bit like asking 'I'd like to buy a V8, how often will I have to visit a petrol station', but not say ho many miles you drive daily. Pointless.
FWIW, we have two EVs, and have survived (until recently) for two years with an ancient 3.5kw charger. No problem. I work from home, so dont use mine much, she has a 25 mile round trip commute.
But yes, OP, please do resists this thread, there has been lots of actual useful information, but it's over to you.
It's a bit like asking 'I'd like to buy a V8, how often will I have to visit a petrol station', but not say ho many miles you drive daily. Pointless.
FWIW, we have two EVs, and have survived (until recently) for two years with an ancient 3.5kw charger. No problem. I work from home, so dont use mine much, she has a 25 mile round trip commute.
But yes, OP, please do resists this thread, there has been lots of actual useful information, but it's over to you.
Gassing Station | EV and Alternative Fuels | Top of Page | What's New | My Stuff