Micro-turbine genset with recuperator gets 60% thermal efficiency converting fuel to 240 AC at 40amps. That means $15 of fuel to charge the Nissan LEAF fully. Typical 30% efficient gasoline generators means $28 to charge. A diesel slow generator costs $22 in fuel to charge. A grid power charge in the 40kWh battery in the leaf less than $5. So no matter how you calculate, portable charging can never take advantage of the economies of scale of grid power production. Locally in Grant Country Washington State, grid power sells for 3 cents per kilowatt, cheapest in the world! We pay 14 cents per kWh locally, while people in the UK pay 30 pence per kWh. Some people in Tokyo, Japan are paying $100 yen or around $1 per kWh.
The economics of EV charging vs fueling a car, highly depend on local fuel prices & local grid power prices. A 2023 Toyota Prius LE 5th Gen base model cost about $30K out the door new and can achieve over 50 miles per gallon while fuel selling locally for $5.10-$5.50 per gallon while ethanol-free E0 premium over $6.30 per gallon. Thats means $0.005 cents per mile using grid electricity in the LEAF and $0.12 cents per mile using regular E10 gasoline in the 5th Gen Prius LE getting over 50 MPG. Most gasoline & diesel cars operating energy costs are $0.30-0.85 per mile by comparison.
A 30kW capstone micro-turbine tied into the battery charger with 400v DC basic Level 3 input with diesel fuel tank mounted in the rear seat & trunk area on a trey that allows easy access & single person unit removal process in modules that link.
Diesel 30kW generators are too large & heavy, like mounting a turbo 2.2-2.4 liter diesel engine & fuel tank, the setup would weight over 600 kilograms. C30 Capstone turbine setup comes in at less than 200 kilograms but way higher cost. I can Alibaba acquire a 30kW diesel generator from China for $3000 new, while the Capstone setup cost more than I paid for the used LEAF SV $20k.
Mounting ten 300W solar PV modules on a folding roof rack system another way to make a portable 3kW trickle charger to slowly keep the battery charged anytime solar hitting the panels. The downside to all of these solutions cost. Given $0.14/kWh & 37 kWh of remaining battery energy storage on 4.6 miles per kilowatt hour, that means a charging cost of under $5, so none of these 30kW fast portable charging solutions are even feasible. To suggest it would be going upside down, an understatement. It makes more sense to trade in the LEAF SV for a 2023 Prius LE that gets 57 MPG on $5.49/gal gasoline locally.
Since last night around 5 PM I have used the EVSE L1 charging cable to trickle charge the LEAF using a power outlet and 50 ft 12-3 extension cable to reach the outlet. I carry around a 50ft 12-3 extension cord in the 25 ft EVSE black zippered storage bag in the rear right of the trunk area so that I have a backup way to capture 3-5 miles of range per hour of charging on the go if I am able to access a regular NEMA 15 power outlet 120v AC at 1600 watts or around 1.6 kW of charging rate LEVEL 1 speed also known as EV trickle charging. Most passenger electric automobiles sold worldwide include a EVSE L1 charging cable that can recharge the EV battery very slowly overnight.
Level 1 EVSE Charging Rate 1.6 kW of charging means that the 40kWH battery pack takes 25 hours to fully charge from 0% to 100% on a regular power outlet. I highly recommend using a braided oxygen free copper 12-3 or 10-3 extension cable not a 14-3 or smaller because the EVSE pulls 1600 watts continuously, enough heat energy at the plug to hot weld the EVSE plug to pins to the charging cable port connectors, meaning you will have a hard time disconnecting them. The thicker wire extension cables have less resistance or impedance to AC flow than thinner cables, so the connections heat up less in thicker high-power cables with smaller wire gauge numbers. The downside of thicker 10-3 and 12-3 cables is that they weigh more & cost more than cheaper, much more common 14-3 cables.
So lower in mass and cost than a portable generator, a longer extension cable to plug into the grid the most economical way to have a portable backup charging solution. There are millions of regular power outlets in the USA for example.
It is also possible to use a small Honda EU2000 or similar generator that burns gasoline, to do portable L1 charging, though a gallon of gasoline in that generator will make 1.6 KW output for 4.6 hours, so you would need to refill it 5 times for one charge. That means a portable recharge like that will cost $28 in fuel + your time to mess with the generator. Plus, you have to change the engine oil every 50 hours, or every 2 charges.
In reality, you will likely never be charging an EV from 0% SOC to 100% on the go using a backup charging cable setup or portable charger generator setup. Moreover, you're likely going to boost your battery until you have enough charge to get home or to work or wherever you are going. Low range EV's like the Nissan LEAV SV 40kWh are not designed for road trips or long trips, they are exceptionally good for local trips to the grocery store or doctor's office or for commuting locally in or between nearby cities in traffic congestion. EV's are better than any other fossil fueled vehicle for start & stop slow speed traffic congestion where gasoline & diesel vehicles are least efficient.
No free lunch in physics! Making electricity on a small scale not cheap or easy in the strange range. When under 50watts its not bad or expensive, but when you get into the 1-100kw range, it becomes a cost, size, thermal efficiency, durability, reliability, mass compromise. This range of power of under 250kW very important to some commercial, some industrial & some military applications, like laser weapons & rail-guns, and backup power for servers & cloud compute infrastructure, for cell tower power backup & energy production in remote low popular areas with few customers.
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