29-05-2021, 11:13 AM
(This post was last modified: 29-05-2021, 11:21 AM by Tony Griffiths.)
Here's a comment I lifted from the paper the other day:
"There currently around 20,000 public charging points in Britain, with another 20,000 private ones - and the SMMT reckons we'll need around 2.3 million by 2030. Only 2.26 million to go - and I make that about 4,750 per week (allowing for holidays). Good luck with that, Greenies!
Now, the “ultra-rapid" chargers that "can charge cars in a matter of minutes". Sounds exciting, but, why are there are so few of them? Here's the reason: take the tiny, useless Renault Zoe - battery 52kWhr, 400-Volt lithium - and do some rough calculations on the current / voltage needed to put 80% of nominal charge into it in five minutes. Feel free to check my working: plugged into a 3-phase, 440-Volt supply that’s over 100 Amps - but how many homes have a 3-phase supply? virtually none. Use the domestic 220-Volt single-phase supply and the power required rises to over 220 Amps - but the typical house breaker trips at 65 Amps - so, that’s a non-starter.
Of course, Motorway service stations and ordinary filling stations have a 3-phase supply, but what if they fit twenty ultra-rapid chargers? With all in use, that's about 2,000 Amps, with two lots of cabling to split the load into something manageable, with each of the three cores (plus earth) being 630 sq. mm. in cross-sectional area, and each core 38 mm in dia. So, maybe the services on the M25, and groups of local garages can club together and buy their own power station driven by a nuclear sub-type reactor from Rolls-Royce? Twenty chargers on a packed M25 - not really enough is it, so, let’s go to forty. Operating simultaneously that’s 0.25MW x 40 = 10 Megawatts of power. That’s a lot of electricity – enough to power 5000 homes - just for one charging station, operating at full capacity. The grid can barely service current requirements – so where will we find 10s of gigawatts of extra power, to recharge a 100% EV fleet? Compare this to a petrol filling station, which is essentially just a big underground tank and a pump. The power is conveniently stored in liquid form, so its much easier and cheaper to handle and deliver. Without some major breakthroughs, all-electric national vehicle fleets are just as much of a fantasy as the rest of the green package of climate “solutions”. Something EV manufacturers hide about rapid-charge stations is that the battery gets very hot - and a quarter megawatt of heat is not easy to dissipate. The Nernst equation says that heat kills cycle life (above ~40C, about 2x per 10C). You can rapid charge often for convenience, but doing so will kill the battery sooner rather than later. Perhaps an undisclosed EV financial warranty liability? My Jaguar iPace has a claimed range of 292 miles, manages 223 on the internal computer at best and could only manage 172 miles last December before running out. Basically, it's an excellent local shopping run-around but absolutely useless as a means of transportation. Thankfully it is leased and will be going back to Jaguar. "
"There currently around 20,000 public charging points in Britain, with another 20,000 private ones - and the SMMT reckons we'll need around 2.3 million by 2030. Only 2.26 million to go - and I make that about 4,750 per week (allowing for holidays). Good luck with that, Greenies!
Now, the “ultra-rapid" chargers that "can charge cars in a matter of minutes". Sounds exciting, but, why are there are so few of them? Here's the reason: take the tiny, useless Renault Zoe - battery 52kWhr, 400-Volt lithium - and do some rough calculations on the current / voltage needed to put 80% of nominal charge into it in five minutes. Feel free to check my working: plugged into a 3-phase, 440-Volt supply that’s over 100 Amps - but how many homes have a 3-phase supply? virtually none. Use the domestic 220-Volt single-phase supply and the power required rises to over 220 Amps - but the typical house breaker trips at 65 Amps - so, that’s a non-starter.
Of course, Motorway service stations and ordinary filling stations have a 3-phase supply, but what if they fit twenty ultra-rapid chargers? With all in use, that's about 2,000 Amps, with two lots of cabling to split the load into something manageable, with each of the three cores (plus earth) being 630 sq. mm. in cross-sectional area, and each core 38 mm in dia. So, maybe the services on the M25, and groups of local garages can club together and buy their own power station driven by a nuclear sub-type reactor from Rolls-Royce? Twenty chargers on a packed M25 - not really enough is it, so, let’s go to forty. Operating simultaneously that’s 0.25MW x 40 = 10 Megawatts of power. That’s a lot of electricity – enough to power 5000 homes - just for one charging station, operating at full capacity. The grid can barely service current requirements – so where will we find 10s of gigawatts of extra power, to recharge a 100% EV fleet? Compare this to a petrol filling station, which is essentially just a big underground tank and a pump. The power is conveniently stored in liquid form, so its much easier and cheaper to handle and deliver. Without some major breakthroughs, all-electric national vehicle fleets are just as much of a fantasy as the rest of the green package of climate “solutions”. Something EV manufacturers hide about rapid-charge stations is that the battery gets very hot - and a quarter megawatt of heat is not easy to dissipate. The Nernst equation says that heat kills cycle life (above ~40C, about 2x per 10C). You can rapid charge often for convenience, but doing so will kill the battery sooner rather than later. Perhaps an undisclosed EV financial warranty liability? My Jaguar iPace has a claimed range of 292 miles, manages 223 on the internal computer at best and could only manage 172 miles last December before running out. Basically, it's an excellent local shopping run-around but absolutely useless as a means of transportation. Thankfully it is leased and will be going back to Jaguar. "