| General > General Technical Chat |
| “Battery EV” vs “Hydrogen Fuel cell EV” |
| << < (6/68) > >> |
| mikeselectricstuff:
--- Quote from: james_s on November 12, 2021, 06:53:52 am ---I don't think that would be difficult at all. The only EV I've lived with for any length of time was a Tesla Model Y, it could charge from the basic charge cable at a rate of 15 miles of range per hour from a 240V 32A circuit, that could be done even with a cheap consumer 8 or 10kW generator. Realistically a roadside assistance vehicle could easily have ~150kW diesel genset and a full fledged mobile Supercharger to give you ~50 miles of range in 10 minutes and the same genset could provide a selection of other charging standards. This is really not that difficult of a problem. --- End quote --- Now calculate the difference in cost between a 150kW generator compared to a jerry can and how that would reflect on your AAA subscription cost. Why do you think it would need anything like that power ? EVs are pretty good at predicting range, so for the occasional user who runs out, it doesn't matter if it takes 30+ mins to charge enough to get to the nearest charge point. 10-20kW would be more than adequate. And once breakdown vans go electric ( or at least PHEV), they can just charge from their battery. |
| richard.cs:
--- Quote from: Rick Law on November 12, 2021, 06:17:49 am ---I think the lack of an easily portable energy source is a huge disadvantage. --- End quote --- Evidence so far is that most EV breakdowns are things like damaged tires. If running out of energy is a small fraction of the total breakdowns then it's no big deal if they have to be handled in a less convenient way like towing to a charger (which may be quicker than a possibly-slow portable charger). In any case electricity has the advantage that it's everywhere, I am fairly convinced that should I run out of electricity somewhere in the UK I could knock on a couple of doors cap in hand and get enough electricity to get to a charger, possibly in exchange for beer money. I've done similar to get water for my petrol car after a coolant leak. Then there's the consideration that many modern engines, including most diesels, won't simply restart if you pour a jerry can in the tank. They need air bleeding out of the fuel system, and whilst not especially difficult this is beyond most drivers putting it in roadside assistance territory anyway. |
| mikeselectricstuff:
--- Quote from: richard.cs on November 12, 2021, 12:50:34 pm --- --- Quote from: Rick Law on November 12, 2021, 06:17:49 am ---I think the lack of an easily portable energy source is a huge disadvantage. --- End quote --- Evidence so far is that most EV breakdowns are things like damaged tires. If running out of energy is a small fraction of the total breakdowns then it's no big deal if they have to be handled in a less convenient way like towing to a charger (which may be quicker than a possibly-slow portable charger). In any case electricity has the advantage that it's everywhere, I am fairly convinced that should I run out of electricity somewhere in the UK I could knock on a couple of doors cap in hand and get enough electricity to get to a charger, possibly in exchange for beer money. I've done similar to get water for my petrol car after a coolant leak. Then there's the consideration that many modern engines, including most diesels, won't simply restart if you pour a jerry can in the tank. They need air bleeding out of the fuel system, and whilst not especially difficult this is beyond most drivers putting it in roadside assistance territory anyway. --- End quote --- And there's always the lamppost + croc clips option... ;) |
| richard.cs:
--- Quote from: mikeselectricstuff on November 12, 2021, 12:56:26 pm ---And there's always the lamppost + croc clips option... ;) --- End quote --- Ah, yes. What the military types like to call a "power of opportunity" cable. |
| tom66:
Hydrogen cars also struggle filling at below -10C. The problem is the hydrogen is transported as a refrigerated liquid, which creates cryo-hazards. In fact, a good hydrogen EV will take about 25-30 minutes to refill at -10C ambient. The other concerning aspect is the cost of a typical refill station. Compressing hydrogen to cryogenic temperatures is not cheap, so most stations use a single compressor and storage plant. The issue is this compressor can only run so fast - typically it runs overnight during down-times - and for the units in Southern California for instance the rate is about one car every 20 to 30 minutes if the station is busy. Not the so-called 5 minute refuel. Look the queues that Mirai owners are experiencing. They're tethered to these stations, no other way around it, whereas at least an EV owner can run an extension lead in most cases! It is also the case that -10C is not a common temperature for most of the world. Some places experience it during winter, others do have the disfortune of experiencing it for longer, but regardless there are places like the UK where even going below 0C is uncommon. EVs can still charge in -10C weather, the charge rate is just reduced and the efficiency is reduced somewhat by using the battery heater. For charging on the street, a typical EV with a 40kWh battery will need to charge about once a week to cover commuting uses. So we do not need a density of chargers to match the number of cars. What we do need is dedicated on-street parking bays with EV chargers, about 10-20% of all spaces on a given street should consist of these. About 50% of homes in the UK have access to off-street parking as well, so they can use their driveway or parking bay as they see fit. We'll also need EV chargers at major destinations for people to 'graze' - already many supermarkets and offices have small numbers of chargers but this will need to increase to ca. 20% of all parking bays, perhaps more. This will allow people to charge up while their car is otherwise unused, without having home charging options. |
| Navigation |
| Message Index |
| Next page |
| Previous page |