There seems to be a standard installation developing for domestic EV charge points where it is 6mm2 no matter what. I checked one installation which will have around 9v dropped on a 7Kw charger. Ok, I acknowledge that the full load current won’t be pulled at all times but it can be assumed that there will be long periods when it will. Multiply that by an ever increasing demand across the nation and we can expect to see considerable energy wastage. Perhaps, we should be setting tighter limits than 5%.
Is a payback period of 6700 hours, worthwhile? In most installs, it is unlikely the car will use 7000 kWh/ year, thus the payback period would probably outlive the car. This is the trouble with just looking at the energy loss, and what is wrong with the BS HD 60364-8 specs, their only idea is to reduce overall consumption at whatever cost. A proper cost/benefit analysis (although mentioned) is often a finger in the air exercise, it is the same with electric motors and VFDs, the tradeoff is never that clear cut unless it is a 24/7 operation.
The point made is a good one although the cost/benefit analysis that I am thinking about is not necessarily a monetary one. Looking at the data for the car and assuming either 6mm2 or 10mm2 is to be installed, I calculate that wastage per 1000miles is around 11KWhrs for the 6mm2 and 6.8KWhrs for the10mm2. Now depending on the cost of electricity and the number of miles per year, I can make a reasonable estimate on monetary pay back. As you say David, it could be quite some time! However, what I can’t accurately say is if the wasted energy is worth saving in terms of CO emissions and how this whole consideration can be scaled to a national level.
Is a payback period of 6700 hours, worthwhile? In most installs, it is unlikely the car will use 7000 kWh/ year, thus the payback period would probably outlive the car. This is the trouble with just looking at the energy loss, and what is wrong with the BS HD 60364-8 specs, their only idea is to reduce overall consumption at whatever cost. A proper cost/benefit analysis (although mentioned) is often a finger in the air exercise, it is the same with electric motors and VFDs, the tradeoff is never that clear cut unless it is a 24/7 operation.
The point made is a good one although the cost/benefit analysis that I am thinking about is not necessarily a monetary one. Looking at the data for the car and assuming either 6mm2 or 10mm2 is to be installed, I calculate that wastage per 1000miles is around 11KWhrs for the 6mm2 and 6.8KWhrs for the10mm2. Now depending on the cost of electricity and the number of miles per year, I can make a reasonable estimate on monetary pay back. As you say David, it could be quite some time! However, what I can’t accurately say is if the wasted energy is worth saving in terms of CO emissions and how this whole consideration can be scaled to a national level.
