EPA Ratings - when?

[KevinRS]

We don’t use gallons/100 miles so the US shouldn’t use kWh/100 miles. But the EPA persists in publishing it. I guess they want to be continental like liters/100km. So they came up with an even more US meangless measure instead of using the miles/kWh Americans could relate to. IMO But that made a gallon of gas look much better than electricity.

Miles per kWh would be just as bad. a 126 MPGe would be 3.8 miles per kWh
People would equate that directly to MPG, even though a gallon of gas is the energy of 33.7 kWh.
A kWh is the equivalent of under half a cup of gasoline.

 

[Moe]

If you’re going to drive an EV, when asked what an eGallon is, respond 33.7 kWh.

 

[Rocks]

Miles per kWh would be just as bad. a 126 MPGe would be 3.8 miles per kWh
People would equate that directly to MPG, even though a gallon of gas is the energy of 33.7 kWh.
A kWh is the equivalent of under half a cup of gasoline.

So the Slate is carrying the energy of less than 2 gallons of gas, and goes 200 miles.

Pretty damaging efficiency comparison, really.

 

[KevinRS]

So the Slate is carrying the energy of less than 2 gallons of gas, and goes 200 miles.

Pretty damaging efficiency comparison, really.

Yeah, gas engines are only 20-35% efficient, the rest is waste heat and friction. Anti-EV arguments will try to point out transmission losses, charging losses, etc, but they just don't compare to gas engine losses. What gas has going for it is capacity and refill speed, but definately not efficiency.

 

[WV Slateman]

Miles per kWh would be just as bad. a 126 MPGe would be 3.8 miles per kWh
People would equate that directly to MPG, even though a gallon of gas is the energy of 33.7 kWh.
A kWh is the equivalent of under half a cup of gasoline.

I prefer watt-hours per mile. I know, it's an easy conversion from KWH/mile or KWH/100 miles, but...

 

[WV Slateman]

Yeah, gas engines are only 20-35% efficient, the rest is waste heat and friction. Anti-EV arguments will try to point out transmission losses, charging losses, etc, but they just don't compare to gas engine losses. What gas has going for it is capacity and refill speed, but definately not efficiency.

...and not having to reduce range by turning on another source of heat.

 

[KevinRS]

...and not having to reduce range by turning on another source of heat.

Yeah, but that's nothing compared to the heat going out the tailpipe and radiator, and just coming off the engine block.

 

[phidauex]

I think we should measure the efficiency in kilogram-meters / second^2, just to keep things simple.

 

[danielt1263]

The purpose of a system is what it does. And it's doing what the legacy OEMs want, making gas look better.

Hence the reason that range is always the first number discussed when it comes to EVs. People hear "half the range of your gas car." and immediately get worried.

 

[Luxrage]

I hope Slate releases the numbers for a variety of body / lift combinations and not just the standard FN. Although I guess it would come down to how many 'versions' the feds see. Definitly SUV/Pickup. But I'd be curious if the lowered one gets some efficiency gains.

 

[Moe]

So the Slate is carrying the energy of less than 2 gallons of gas, and goes 200 miles.

True. However “filling” an EV is also like pumping gas with a leaking hose. You will pay for more energy than goes into the battery/tank. Some is lost as heat.
.

 

[WV Slateman]

True. However “filling” an EV is also like pumping gas with a leaking hose. You will pay for more energy than goes into the battery/tank. Some is lost as heat.
.

Do we know the efficiency of the charger yet? It's something I'd like to know, since I'll be charging it both from solar and a battery bank.

 

[Moe]

Do we know the efficiency of the charger yet? It's something I'd like to know, since I'll be charging it both from solar and a battery bank.

I haven’t seen that. Tesla combines the efficiency of charging and efficiency of driving when they say for example 12/15A Level 1 gets 3 miles per hour of charging. That works out to be ~70% at 3 mi/kWh.
.
edit: maybe I have seen something like that from Slate but have forgotten it.

edit 2: since I’ll be using Level 1, 3 mi/hour most of the year an 2 mi/hour average in winter is what I’m hoping for.

 

[phidauex]

Do we know the efficiency of the charger yet? It's something I'd like to know, since I'll be charging it both from solar and a battery bank.

The losses in the onboard charger itself will be very low, maybe in the 96-99% efficiency range. There are some losses in the battery chemistry, the cabling to your EVSE, and the vehicle's controller and electronics.

My guess will be that the net charging efficiency (kWhs from your electric meter to usable kWhs stored in the battery) will be in the 93-96% range when charging at 240V, 20-40A. It could be a lot less for 120V charging, maybe in the 75-85% range, with the vehicle overhead being a much bigger fraction of the loss.

 

[WV Slateman]

The losses in the onboard charger itself will be very low, maybe in the 96-99% efficiency range. There are some losses in the battery chemistry, the cabling to your EVSE, and the vehicle's controller and electronics.

My guess will be that the net charging efficiency (kWhs from your electric meter to usable kWhs stored in the battery) will be in the 93-96% range when charging at 240V, 20-40A. It could be a lot less for 120V charging, maybe in the 75-85% range, with the vehicle overhead being a much bigger fraction of the loss.

Yes, I'm aware of the other losses. The unknown is the efficiency of the charger. Between the charge controller and inverter, it's already down to about 85-87%.