Roger Mills wrote:
On 20/10/2020 18:29, Tim+ wrote:
The Natural Philosopher wrote:
On 20/10/2020 16:29, Roger Mills wrote:
Although a lot of my journeys are short, I do enough long journeys to a
BEV unviable with the range currently available. Hopefully battery
development will yield higher capacity batteries without increasing the
size and weight. Even so, a full charge will then take longer.

fast charging is something batteries can already do - a one hour flat to
full is well within lithium capabilities, but I haven't seen much in the
way of better energy to weight in the last ten years. Cost is about half
what it was ten years ago.

The limits on fast charging is really the local last mile grid. Few
houses have 100A fuses and that is the limit for a normal domestic
installation. 25kW will still take 4 hours to cram the electrons into a
100kWh battery...leaving nothing left over for the mandatory house
heat-pump.



But you dont need fast charging at home. A 7kW charger is quite adequate
for overnight charging.

Tim


That depends on battery size. If higher capacity batteries are developed
which produce an acceptable range, 7kW my well not be enough.

My car has a 65kWh battery and a real world range of 250-280 miles. In
theory, about 10 hours to fully charge then. Okay, there are cars that
have bigger batteries but how many people are likely to use all their range
every day and not have enough time for 8- 12 hrs charging at home?

Yes, you can invent scenarios where you might struggle to fill a large
battery fully every night at home but youd have to be clocking up some
serious mileage! In practice, 7kW for home charging is more than adequate.
Based on a 3.5miles/kWh that my car easily achieves, thats charging at a
rate of about 25 miles range every hour.

Tim

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