what is your EV charger grid limit?
Discussion
kambites said:
My thought is that I don't understand the question. 
if you have a harvi module which monitors the current being drawn into the whole property you can set the zappi so that it will stop / reduce charge when the threshold is set.my mains supply (single phase) has a 100A fuse so theoretically I can draw about 23KWH in 60 minutes but my zappi is set to stop charging when I go over 14KWH.
So your EV charger is set up to stop charging if your whole-home draw in any one-hour period ever goes above 14kWh? Why on earth would you want such a limit?
ETA: Or do you mean it throttles moment-by-moment to 14kW total grid draw? That would seem more... useful, since it would allow you to run the charger with a smaller main fuse without risk of blowing it. Still pointless if you have a 100amp main fuse though. We have no such limit in place as far as I know, not that I think we'd ever have noticed if we did!
ETA: Or do you mean it throttles moment-by-moment to 14kW total grid draw? That would seem more... useful, since it would allow you to run the charger with a smaller main fuse without risk of blowing it. Still pointless if you have a 100amp main fuse though. We have no such limit in place as far as I know, not that I think we'd ever have noticed if we did!
Edited by kambites on Friday 13th November 10:30
kambites said:
So your EV charger is set up to stop charging if your whole-home draw in any one-hour period ever goes above 14kWh? Why on earth would you want such a limit?
I have friends who live in very rural places. They have iffy grid and have to be careful about how much is drawn at times as it trips some fuse in the grid and affects about half a dozen houses in the valley. But we are talking west coast Scotland....POIDH said:
kambites said:
So your EV charger is set up to stop charging if your whole-home draw in any one-hour period ever goes above 14kWh? Why on earth would you want such a limit?
I have friends who live in very rural places. They have iffy grid and have to be careful about how much is drawn at times as it trips some fuse in the grid and affects about half a dozen houses in the valley. But we are talking west coast Scotland....kambites said:
Yeah capping the power would make some sense in some niche situations, if that's what the OP meant to say.
However, I suspect it is not that.My SyncEnergy charger allows me to set limits on charging speed. I just set to the maximum (I cannot remember what now) and leave Octopus and Sync to manage how fast the car charges as my understanding was that Octopus can control both when and what speed.
Units:
kW = kilowatt. A kW is a unit of power (1 kW = 1.34 hp). Used for e.g. the power of a car (petrol or electric) which determines its acceleration, and also the rate at which an EV can be recharged. Electrical power is equal to voltage times current, so for example a typical three-pin charger runs at 10 Amps (current) and 240 volts making 2,400 watts or 2.4 kW.
kWh = kilowatt-hour. A kWh is a unit of energy, it's the amount of energy delivered by running at 1 kilowatt for one hour. Used for e.g. the capacity of a battery, and also its total remaining charge.
OP uses kWh but it seems like it's meaning kW.
Many houses have a 60 Amp main fuse, 60 x 240 = 14.4 kW maximum power. Newer or rewired houses may have 100A, so 24 kW. If you are in any danger of hitting this limit, it makes sense for your charger to be set to reduce its power as your total draw nears the limit to avoid tripping the circuit breaker.
I agree that if you have a 100A fuse, curtailing the charger as you near 14 kW total household draw seems unduly conservative. Having said that, it's only an issue if you are in fact seeing the charger ramp down for this reason. But yeah logically a 100A fuse corresponds to a 24 kW total for the house, so there's no need to limit the charger power at a lower level than this.
kW = kilowatt. A kW is a unit of power (1 kW = 1.34 hp). Used for e.g. the power of a car (petrol or electric) which determines its acceleration, and also the rate at which an EV can be recharged. Electrical power is equal to voltage times current, so for example a typical three-pin charger runs at 10 Amps (current) and 240 volts making 2,400 watts or 2.4 kW.
kWh = kilowatt-hour. A kWh is a unit of energy, it's the amount of energy delivered by running at 1 kilowatt for one hour. Used for e.g. the capacity of a battery, and also its total remaining charge.
OP uses kWh but it seems like it's meaning kW.
Many houses have a 60 Amp main fuse, 60 x 240 = 14.4 kW maximum power. Newer or rewired houses may have 100A, so 24 kW. If you are in any danger of hitting this limit, it makes sense for your charger to be set to reduce its power as your total draw nears the limit to avoid tripping the circuit breaker.
I agree that if you have a 100A fuse, curtailing the charger as you near 14 kW total household draw seems unduly conservative. Having said that, it's only an issue if you are in fact seeing the charger ramp down for this reason. But yeah logically a 100A fuse corresponds to a 24 kW total for the house, so there's no need to limit the charger power at a lower level than this.
Thanks for all the replies.
The only reason I am asking this is that I want to shift more usage to the off peak times.
I work from home so as winter approaches I am fortunate enough that I get off peak during the day and can use an oil filled radiator rather than gas.
I'm going to up it by 1 or 2 KWh and see how it goes.
BTW there are no fuse tripping issues here it was set this way by the installation electrician.
The only reason I am asking this is that I want to shift more usage to the off peak times.
I work from home so as winter approaches I am fortunate enough that I get off peak during the day and can use an oil filled radiator rather than gas.
I'm going to up it by 1 or 2 KWh and see how it goes.
BTW there are no fuse tripping issues here it was set this way by the installation electrician.
Greenmantle said:
Thanks for all the replies.
The only reason I am asking this is that I want to shift more usage to the off peak times.
I work from home so as winter approaches I am fortunate enough that I get off peak during the day and can use an oil filled radiator rather than gas.
I'm going to up it by 1 or 2 KWh and see how it goes.
BTW there are no fuse tripping issues here it was set this way by the installation electrician.
A normal home charger has a maximum power of 7 kW.The only reason I am asking this is that I want to shift more usage to the off peak times.
I work from home so as winter approaches I am fortunate enough that I get off peak during the day and can use an oil filled radiator rather than gas.
I'm going to up it by 1 or 2 KWh and see how it goes.
BTW there are no fuse tripping issues here it was set this way by the installation electrician.
The 'limit' feature means that if your total home power draw approaches 14 kW while the charger is active, the charger will reduce its power to avoid the overall total exceeding 14 kW.
For instance if your power is 1 kW, you turn on the charger, that adds 7 kW, the household total is 8 kW.
Now if you go and use say an electric shower at 8kW, the total would reach 16 kW.
BUT what happens is the Zappi detects this and throttles back the charging to 5 kW, so that 1 + 5 + 8 = 14 kW which is the set limit.
When you stop having a shower and the household load falls back to 1kW, the Zappi will go back up to full power of 7 kW.
So the question is, at present is the household load reaching 14 kW while the charger is active? Because if it's not, the charger will already be running at its full power of 7 kW, and increasing the limit will have no effect.
OTOH if heating the oil-filled radiators are taking a lot of power, then yes it might be relevant, and increasing the setting will help.
But you won't get more than 7kW out of the Zappi, whatever you do with the limit.
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