I spy (I think) 12 AC (3phase) motors, Presumably about 200hp each, with losses giving a combined 2200hp. - crazy. They claim 5 minutes + reserve at full power, so perhaps at a guess 10min full power with no cruise (that will be my assumption for all this anyway) 2200hp is 1.64Mwatt an hour. So for 10 mins 0.27Mw or 984MJ (Mega Joules).
Presumably its using Li-ion batteries. Currently Li-ion has a power density of 250-340w/KG (according to online references) If running at full power for 10 mins this thing uses 0.27Mw of energy, that would require around 900kg of batteries, assuming 100% discharge 300w/kg and 100% efficiency, so in reality probably nearer 1000-1500kg + or so, to take account that totally discharged Li-Ion batteries can explode and inefficiencies etc..
If looking at typical uk power supplies going onto the average home ~240v 100A gives you a maximum of 24Kw/hr of power (leaving nothing for anything else). To restore the batteries in this boat back to where they were before your 10 minute blast would take around 11-12hours and cost around £43 at current elec costs of 15p a unit...
Ok trying the same with petrol, will be interesting to see if this rings semi accurate with those who get to play with this amount of power?
For comparison most petrol engines run at best around 25% efficient. So, 2200hp of petrol engines which we know is roughly 1.64Mw/hr or 5904MJ (an hour) or 984MJ (ten mins) of useful power @ 25% efficiency would mean we require 3936MJ of fuel. If fuel has approx 46MJ/Kilo that gives approx 86 litres of fuel in 10 minutes...
A few things in perspective:
12hours of totally maxing out your home grid supply is about the same as 86 litres of useful work form petrol...
1 KG of petrol provides 46MJ of energy.
1 KG of Li-ion batteries provides about 0.3MJ of energy.
Looking at it from cost per amount of energy provided:
Roughly £1.30 gives you 46MJ of energy from petrol = 0.35p/MJ
Roughly £0.15 gives you 3.6MJ of energy from the Grid @ 15p/unit. = 0.24p/MJ
not done that before, not realised in the past that home elec was so expensive per Joule compared to petrol for example, which I would have thought would be much more expensive given all the petrol taxes..
Seems to me that an elec car will never be a cheap thing to do given that grid supply unless I've really ballsed up somewhere is not THAT much difference from that of petrol energy cost...
Anyone still with me? Any mistakes I've made?