Tesla with a generator on a hitch haul

I agree kwh is correct--but I was doing a "paste" from the tesla report.

pianotuna wrote:
rjstractor,

I found 24 kw to move 100 miles, on the wobbly wide web. (model 3 Tesla)

However I did not know that when plugged in the tesla won't move. I guess that is a good safety feature.

Don, a Model 3 doesn't go 100 miles on 24 kilowatts, it goes 100 miles on 24 kilowatt/hours. I think you're confusing the concepts of absolute power output (kw) and power output over time (kw/hr). It's kind of like the idea of torque and horsepower.

Since the car takes 24 kw/h to go 100 miles, that little generator would need to run for just over 9 hours at 2.6 kw to produce that much power. So the car would be moving at about 11 mph. That's assuming it was able to put all that power into the car battery, which it can't. To move the car at highway speed (60 mph) for 100 miles, the generator would need to produce the 24 kw/h in 100 minutes, which requires a generator with a power output of 15 kw. That's a pretty big generator to pack on a hitch hauler. :B

Reisender.

Thanks for the update on not moving and charging.

mkirsch wrote:

Reisender wrote:
Yah. I agreed with everything you just said. But for pre-heating the Tesla doesn’t work like that. The poster mentioned he had been running the genny for 24 hours. It takes 5 or 7 minutes to pre-heat the tesla and it can do it from it’s own battery. He or she was running the genny for other reasons. Probably low charge. Makes sense, albeit really slow. Even at 24 amps 120 volts from that genny.

Maybe you missed the part about "severely reduced capacity in cold temperatures?"

Sure you can warm it up using its own batteries, but how much of a hit on range will there be pulling from the cold batteries?

Maybe the owner ran the generator to keep the car and batteries warm for the 24 hours it sat there, rather than let the batteries get cold and having to start from scratch? That generator can't run for 24 hours at full capacity, and isn't all that quiet so I doubt it was actually charging the car. Those Hondas are really only quiet at idle.

To go from minus 20 to plus twenty in our driveway while not plugged in takes 5 or 7 minutes. It’s about a 2 percent hit on the battery. I’m not sure what severely reduced capacity means but typically around here one should count on losing about a third of your normal range for the winter temps we get.

Teslas don’t have anything like a block heater function. Just plugging it in won’t keep anything warm. The cars needs to be actively charging for heat to be diverted for battery warming.

Again. Not questioning the drivers motives for plugging in. More than likely he had a good reason. But pre-heating wouldn’t be one of them unless he wanted to keep the interior of the vehicle warm continuously for days on end. Maybe a pet inside. Who knows.

Agreed on the noise of the genny. We have a 3400 watt propane genny that we use for emergency home backup. Once every couple months we exercise it and use the Tesla as a variable load as I can vary it from 5 to 24 amps on 120 volts. Works well. But when up at 24 amps it’s working hard and is considerably louder. Meh. It’s once every couple months for 20 minutes and the neighbour does the same thing so it’s all good.

Pre-conditioning on navigation to a supercharger is another topic. In this case the battery is preheated about 30 minutes or so before arriving at a supercharger. This insures max charge rate when arriving at the supercharger. But that’s all automatic and outside the scope of this conversation.

Cheers.

Reisender wrote:
Yah. I agreed with everything you just said. But for pre-heating the Tesla doesn’t work like that. The poster mentioned he had been running the genny for 24 hours. It takes 5 or 7 minutes to pre-heat the tesla and it can do it from it’s own battery. He or she was running the genny for other reasons. Probably low charge. Makes sense, albeit really slow. Even at 24 amps 120 volts from that genny.

Maybe you missed the part about "severely reduced capacity in cold temperatures?"

Sure you can warm it up using its own batteries, but how much of a hit on range will there be pulling from the cold batteries?

Maybe the owner ran the generator to keep the car and batteries warm for the 24 hours it sat there, rather than let the batteries get cold and having to start from scratch? That generator can't run for 24 hours at full capacity, and isn't all that quiet so I doubt it was actually charging the car. Those Hondas are really only quiet at idle.

pianotuna wrote:
rjstractor,

I found 24 kw to move 100 miles, on the wobbly wide web. (model 3 Tesla)

However I did not know that when plugged in the tesla won't move. I guess that is a good safety feature.

Good morning Don. It’s not just Tesla. It’s any electric vehicle that uses a J1772 charging protocol. So 100 percent of all electric vehicles that are not home built. Once it is plugged in it’s not moving.

rjstractor,

I found 24 kw to move 100 miles, on the wobbly wide web. (model 3 Tesla)

However I did not know that when plugged in the tesla won't move. I guess that is a good safety feature.

rjstractor wrote:

pianotuna wrote:
Tesla uses 2.4 kw per mile at highway speeds. The generator could keep up with that, since it does about 2.6 kw.

Gary thanks for the link.

I'm not sure how you came up with that, but your math seems a little goofy. 2.6 kw is just over 3 hp. It takes a lot more than 3 hp to move a 4000 lb car at 60 mph, regardless of how efficient it is.

My math came up a little different. I googled that the average Tesla uses 34 kwh per 100 miles at highway speeds. That's 340 watt/hours per mile. In one hour at 60 mph, you obviously travel 60 miles, so 340 watt/hours x 60 = power consumption rate of 20.4 kw. That equates to just under 28 hp, which sounds much more reasonable to move a 4000 lb car at 60 mph.

I think the confusion is in the difference between motive force required to move the car and how much energy the car uses in a certain distance. For example, after 7 years of driving an EV our lifetime average is 6.4 kilometres per 1 kwh of electricity. Which of course is different than what it takes to actually push the car down the road at 100 kph.

pianotuna wrote:
Tesla uses 2.4 kw per mile at highway speeds. The generator could keep up with that, since it does about 2.6 kw.

Gary thanks for the link.

I'm not sure how you came up with that, but your math seems a little goofy. 2.6 kw is just over 3 hp. It takes a lot more than 3 hp to move a 4000 lb car at 60 mph, regardless of how efficient it is.

My math came up a little different. I googled that the average Tesla uses 34 kwh per 100 miles at highway speeds. That's 340 watt/hours per mile. In one hour at 60 mph, you obviously travel 60 miles, so 340 watt/hours x 60 = power consumption rate of 20.4 kw. That equates to just under 28 hp, which sounds much more reasonable to move a 4000 lb car at 60 mph.

mkirsch wrote:

Reisender wrote:
Ok. But pre-heating is not the reason he has it plugged into a generator. It was mentioned that there was a charging station close by so range extension wasn’t either. Unless maybe he didn’t know it was there or maybe it was broken or who knows. But you definitely don’t need a generator or any power source for pre-heating or pre conditioning. We have a project going on in the garage right now so every night our tesla sits outside in minus 20 degrees celcius or worse and not plugged in. Pre-heating consists of pulling out the phone and selecting the pre-heat control on the App. 5 to 7 minutes later the Interior of the car has gone from minus 20 to plus 20 and the windows are defrosted and the seats are warm.

Why wouldn't it be the reason? I've been flying electric radio controlled airplanes for years that use lithium batteries similar to what you find in modern EVs. In cold temperatures the battery capacity is severely reduced. Sure you can use the battery to warm itself but the capacity is still severely reduced (usually permanently at this point), so we'd put them inside our coats to warm them before going flying. An external source of heat. So you're not drawing down and damaging the already stressed battery until it is up to operating temperature.

Maybe there was a charge station "nearby" but it was not THERE. Maybe the car owner didn't know there was a station there.

People love to post pictures like this, point, and make fun. I fail to see anything fun or funny about it. It's very practical in locations that may not have infrastructure to support EVs yet.

Wonder if the guys with horses used to point and laugh at the first car guys who brought along extra gasoline to areas where gas stations had not reached yet.

Lookit this guy... What an IDIOT!!!

Yah. I agreed with everything you just said. But for pre-heating the Tesla doesn’t work like that. The poster mentioned he had been running the genny for 24 hours. It takes 5 or 7 minutes to pre-heat the tesla and it can do it from it’s own battery. He or she was running the genny for other reasons. Probably low charge. Makes sense, albeit really slow. Even at 24 amps 120 volts from that genny.