Monitoring EV running costs

[Howard]

I have a friend with a Tesla and a Tesla "Powerwall". I believe the combination does provide two way power generation already. I couldn't understand the economics to be honest because the initial financial outlay seemed so large that the payback would take years. However he is pleased with it and the technology works fine. Again, whether it is "green" in the short term is debatable.

Our BEV wasn't leased to save money but it is a satisfying car to drive. I'd be very happy to leave it plugged in every day and let its computer and the smart charger work out when to charge or supply electricity within the limits that I can already set.

Living in the country I am very aware of the air pollution in our local city. Walking a short distance, the traffic fumes are very noticeable. I was also aware of this during a recent walk in London. Electric cars can really help reduce this problem.

Maybe this is a very middle class thing, but it is quite fun having a BEV. It is wonderful for short journeys in very cold conditions because the heated seats and steering wheel are warm literally after driving less than 100 yards and the fan heater also produces instant warm air for the screen etc. Is it worth paying more for? Well our BEV is costing much less to run than the previous ICE Golf at current electricity prices and current petrol prices

regards

Howard

[AF62]

Presumably your concern about 2 way electricity has been solved for each solar panel installation.

It has, but that link indicated an additional cost to the EV charger of £5k, which they hoped would come down to an additional £1k.

As for a car with a range of in excess of 100 miles being left discharged before the work commute, it would be unlikely in the morning and if plugged in at work (work being on a V2G tariff), then surely the car can know the likely commute distance and ensure that it has enough energy. That is unless you tell it that you need it to have a full charge. Indeed it's likely that the car would even roughly know when you are likely to use it.

The trouble is that people are used to just jumping in the car and driving, not hoping the car ‘thinks’ it knows how far you want to go - does it know that this Friday you are off to see friends 200 miles away not the usual 15 mile drive home?

Extra computing power? Now you are having a laugh. All modern cars are computers on wheels and some receive software updates via the phone network as you use them.

I didn’t mean extra computing power, but the additional electrical wiring to allow the bi-directional flow of electricity - as noted in that link only the Nissan Leaf had the wiring to allow that, and EVs are built down to a price.

Why would someone leave an EV plugged in? During winter or summer when they want to get into a car with a comfortable temperature? No need to drain the battery before you drive.

Mine will heat or cool plugged in or unplugged, and to be honest it is much nicer to jump in and drive away without faffing around in the cold, unplugging and storing away the cold wet cable.

By the way, did you follow any of the previous links? The Ofgem one mentioned a possible payment of £725pa. I would agree that isn't substantial, but it might be significant. Especially were one to lease rather than own the car and hence battery. Others were large businesses who presumably are not doing it totally altruistically.

I noticed they didn’t say what the average payment was, only that was the maximum someone had been paid (and I am always suspicious when numbers are selectively quoted).

At the price they were buying the ‘exported’ electricity of 30p/kWh less the cost to buy it in the first place (at best 5p) then someone would need to be ‘exporting’ 8kWh a day, every day of the year. That seems unlikely for the average person. And it would still have taken them 7 years to be in profit given the extra cost of the charger.

Finally, have you considered the possibility of regulation? The law now requires that a EV charger be fitted to any new house built. How large a stretch would it be for Ofgem, you know the author of the first link, to regulate on such chargers.

You could regulate their install, although at an additional £5k that would kill the EV charger rollout, but could you legislate that someone must plug their car in…

Never? Well you might be right.

It is lIke a lot of things with EVs (and ‘green’ in general) - a lot of taxpayers money is being thrown against the wall and the politicians and lobbyists hope that some of it sticks - and if it doesn’t, ah well never mind as it wasn’t their money.

[9873210]

I didn’t mean extra computing power, but the additional electrical wiring to allow the bi-directional flow of electricity - as noted in that link only the Nissan Leaf had the wiring to allow that, and EVs are built down to a price.

Wild speculation, but ...
Every EV with an AC motor (which means almost all of them, including the ones with misnamed brushless DC motors) has a power controller that can directly produce or consume a wide variety of wave forms, and could with proper programing be directly connected to the grid in a bidirectional fashion (at some particular speed and acceleration the motor needs 240VAC at 50Hz. At the same speed and some deceleration, the motor generates 240VAC at 50Hz, or possibly it would be best to use 120VAC and a transformer depending on details of the car).

I don't know if anybody combines the motor controller and charger, but it should be possible if the cost of the electronics is a limiting factor. The charging station would be a plug. Wires are of course bi-directional

At the price they were buying the ‘exported’ electricity of 30p/kWh less the cost to buy it in the first place (at best 5p) then someone would need to be ‘exporting’ 8kWh a day, every day of the year. That seems unlikely for the average person. And it would still have taken them 7 years to be in profit given the extra cost of the charger.

Because power electronics can produce arbitrary waveforms the car can provide grid services such as frequency stabilization and power factor correction. These can be worth more than bulk power. There are even places where the grid actually pays for them rather than assigning them by regulatory fiat. This would need a really smart grid.

[Urbandreamer]

Wild speculation, but ...
Every EV with an AC motor (which means almost all of them, including the ones with misnamed brushless DC motors) has a power controller that can directly produce or consume a wide variety of wave forms, and could with proper programing be directly connected to the grid in a bidirectional fashion (at some particular speed and acceleration the motor needs 240VAC at 50Hz. At the same speed and some deceleration, the motor generates 240VAC at 50Hz, or possibly it would be best to use 120VAC and a transformer depending on details of the car).

I don't know if anybody combines the motor controller and charger, but it should be possible if the cost of the electronics is a limiting factor. The charging station would be a plug. Wires are of course bi-directional

I strongly suspect that 9873210 is aware, but most machinery that uses large electrical motors has what he describes, ignoring the battery bit. Breaking or slowing motors is often a requirement. Progressive control of friction breaks is not easy and they wear out. Hence historically energy generated by the motor that you wished to slow was dumped into a "breaking" resistor which glowed red. Today the energy is exported back onto the grid reducing the energy consumption that must be paid for or used to power a different motor.

Structurally it's not the same circuit. One circuit converts between mains and high voltage DC. Other circuits convert between high voltage DC and waveforms ( or AC) for each motor. The AC to DC is as complicated as the DC to AC, as they are both bidirectional.

Back to EV's. The Type 2 connector can use either DC or AC, I am unsure if charging is done by the wall charger when using DC. If so then the car may need little modification. The batteries being simply connected to the wall charger after protocol negotiation. I heard this claimed to be the case, but can't state that I know it to be true for all EV's.

The on car, charging circuit, will be used if the car receives AC. Clearly it could be designed to allow energy to pass the other way as could the wall charger. Depending upon the design of the existing equipment it may need expensive replacement. A lot cheaper to do as original equipment though.

Hope that you all find this information of use.

[scotview]

I have looked into Vehicle to Home (V2H) a little bit. One of the issues that I haven't had a definitive answer to from either BEV or home battery manufacturers is how to provide a suitable earth to replace the grid earthing system in the event of a power cut. The home's circuit must be isolated from the grid for safety reasons in the event of a power cut, if battery backup is to be used. Earthing seems to be a real issue.