Cybertruck Energy Consumption at Slow Speeds

ajdelange

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At very slow speeds you don't cover much ground per hour so you can drive all day and all night without charging (and then some).
He is interested in how far he can go - not how long.

Interesting graphs which make sense seeing the non-drive parasitic loads with rolling resistance versus drivetrain loads only reach equilibrium at 40kmh, where aero is still insignificant.

But at lower speeds like 6mph (10kmh) there is are not many data points in those graphs so I'd be wary of making to many assumptions.
Caution is certainly called for here and any guess is at best a WAG in particular because we will be dealing with a new motor about which we know little. We know it is an IM which means that at first blush it's less efficient than an PMSRM motor but we also know its not the kind of IM we learned about in school.


What would be interesting to see in comparison is parasitic loads in a stationary vehicle in the same temperature conditions to plot against a speed/range graph. So actually harder to estimate than it looks like for such low speeds.
Impossible, in fact but what he really wants to know is whether he can run his cable business with a CT. He is talking about 6 mph. If he is doing 10 hour days that's 60 miles. Let's assume the EPA rating is 500 Wh/mi and that efficiency is 20% worse at 6 mph. That means consumption of 625 Wh/mi 37.5 kWh or 18% of a 200 kWh battery. If he plugs in equipment which takes 2 kW average draw in a 10 hr shift that's another 20 kWh (10%). If he runs the air conditioner or heater the whole time that's another 10%. Knocking the traditional 10% off each end he will have used 60% of his battery leaving himself 40% to get back to the shop. That's 200 miles worth. So it's clear he can accomplish his mission. But I get the sense he is more intrigued by the idea of modeling this more than by desire for this simple answer.


In a ideal world without parasitic loads the range would be infinite with a solar vault cover, (you can push a CT along by hand after all - like most cars) But it's unlikely the parasitic loads can be reduced that far.
I'm sure you have seen the various calculations that have been done for the hypothetical solar tonneau. Above we calculated that at 6 mph in a 10 hr shift he might use 37.5 kWh for just traction. No tonneau is going to cover that - even in a place where the sun shines every day.


Does anyone know how much the self discharge is of a parked Tesla?
Mine takes about 100W. In a 10 hr shift that's half a percent of a 200 kWh battery. I draw more than the average (which is about half that) because I have two logging apps pinging her for data.



And then one with "ignition on" but not in drive?
That depends on what you have on with the long pole in the tent being cabin and battery temperature conditioning loads.
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I'm sure you have seen the various calculations that have been done for the hypothetical solar tonneau. Above we calculated that at 6 mph in a 10 hr shift he might use 37.5 kWh for just traction. No tonneau is going to cover that - even in a place where the sun shines every day.
I did set out "ideal conditions without parasitic loads" in my statement. The point being that even a few 100W (in this case about 500-800W from the cover pending PV type) will propel a vehicle at some low speed whilst the sun shines directly overhead in a "ideal world". Maybe not 6mph but maybe 2-3mph on a flat sealed surface.

Mine takes about 100W. In a 10 hr shift that's half a percent of a 200 kWh battery. I draw more than the average (which is about half that) because I have two logging apps pinging her for data.

That depends on what you have on with the long pole in the tent being cabin and battery temperature conditioning loads.
100W is actually quite substantial. Do you know how much of that is system consumption vs battery self discharge?

My passive house "asleep" (with us 4 in bed) is typically between 30-40W at night with some ambient lights, cameras, security, automation and internet on. When the inverter fridge comes on about 2-3 times and hour for a couple of minutes, it goes up to 130W. The house off-grid inverter uses another 15-20W itself and whilst scanning for loads. I don't have any data on battery self discharge yet. The off-grid inverter can also run batteryless, meaning the battery only gets one cycle a day and then the battery stays off until the sun goes down.

In another comparison to a Tesla, I'm wondering what the implications of insulating the cabin and battery would be, and how favorable that would be. The trick with having a passive home that runs on less than 1kW average (in our case 400W including HVAC) is to stop thermal transfers that leak heat to where you don't want it. I'm sure a bit of insulation can't hurt, Mercs have had double glazed windows for decades. In that regard the SS of the CT will be better than Aluminum in a MS/MX, driving vehicles have heaps of convection potential to boot.
 
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bfrench

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I get the sense he is more intrigued by the idea of modeling this more than by desire for this simple answer.
Yes, this is absolutely the case. And thank you (and the community) so much for indulging in this hypothetical question - I knew there was a vast brain trust here.

The use case scenarios for slow-speeds are as numerous as the unknown variables, so this is presently a research exercise to develop models for predictions given a future when some of the factors may be more precisely defined.

My interest in this research is broad, but centers on the basic idea that Cybertruck is a mobile energy platform capable of transforming work - and by "work" I mean many types of commerce from field research to extreme film-making, to surveying remote regions, and emergency/first responder services. Cybertruck (and perhaps future Tesla variants) are likely to captivate commercial activities as much as it will facilitate lifestyle adaptations in travel and recreation.

I chose 2x the average walking speed as a worst-case scenario in an attempt to tease out the impact of the hidden side of electrification - many of the fixed costs that business people like me would miss.

Blown away by the contributions and I hope someday to share my findings.
 

ajdelange

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100W is actually quite substantial. Do you know how much of that is system consumption vs battery self discharge?
Yes it is. 2.4 kWh (2.4% of my battery) per day. I'm pretty sure that the vast majority of that is comsumption as I do use TelaFi and Stats plus whatever the car needs for house keeping etc. Whenever I go near the car, the lights flash and the driver side door opens.

My passive house "asleep" (with us 4 in bed) is typically between 30-40W at night with some ambient lights, cameras, security, automation and internet on.
Just for comparison my baseline load is about 2.5 kW.
 

JBee

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Just for comparison my baseline load is about 2.5 kW.
Bitcoin miner? Or are you Santas neighbour? :cool:

With the data collection running does that mean the main CPU is on too? It won't be the radio power otherwise you'll be getting nuked.
 

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Bitcoin miner? Or are you Santas neighbour?
I really don't know where most of it is going! I do have a walk in cooler (my mania used to be beer) and that takes an aveage of 184 watts. I think the rest of it is stuff like WiFi hotspots, computers and TV's in idle, refrigerators, the controls for the various HVAC gear, the instant hot water heater (been meaning to unplug that) wall warts, the fiber interface, ethernet switches, the router, the security cameras, the eGauge, the sump pumps...


With the data collection running does that mean the main CPU is on too? It won't be the radio power otherwise you'll be getting nuked.
Some watch dog part. I don't know if the CPU wakes up from time to time, checks in with the mother ship and goes back to sleep or if the modem is on and always listening for a ping from the mother ship. Seems like the latter since I can blow the horn or flash the lights at any time.
 
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JBee

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I really don't know where most of it is going! I do have a walk in cooler (my mania used to be beer) and that takes an aveage of 184 watts. I think the rest of it is stuff like WiFi hotspots, computers and TV's in idle, refrigerators, the controls for the various HVAC gear, the instant hot water heater (bben meaning to unplug that) wall warts, the fiber interface, ethernet switches, the router, the security cameras, the eGauge, the sump pumps...


Some watch dog part. I don't know if the CPU wakes up from time to time, checks in with the mother ship and goes back to sleep or if the modem is on and always listening for a ping from the mother ship. Seems like the latter since I can blow the horn or flash the lights at any time.
Best way for me was to systematically go through and plug a energy monitor into every power outlet for a day. Then start thinking about which ones you need to permanently disconnect, then grab some master slave power boards for turning peripherals on when you use the PC etc. And finally grab some small sonoff wifi switches from Banggood to automate and monitor (have a power meter built in as well as a wifi controlled relay) those you can't live without.

In my case I have wired the whole place up with low voltage DC consumers in mind, so with DC cabling for lights, USB-C chargers in the wall, POE LAN, etc. And then for 240V each power point, or max two pp is wired separately back to a din relay board to a service cabinet in the middle of the house (to reduce wiring losses) and so I can control each circuit separately, or pull some other cable through the conduit as required. All the wiring is routed through the second storey floor.

The big users are typically ones that have some sort of thermal output, fridge is a common culprit. I tell RE customers they're better off buying a better fridge than buying more solar from me. What you don't use can never wear out or run out. ;)
 

ajdelange

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It's amazing how the little loads add up. I'm doing a garage and it will be totally solar. No panels are up yet and no Powerwalls so I running it from a Yeti so the workmen will have lights, can open and shut the garage doors etc. Besides that stuff there is an Ethernet switch and the device that measures the loads which are on continuously. The average load is 52W. But even that amounts to 1.26 kWh/day. In a solar system that may only produce 26 kWh/da in the winter that's an appreciable load (5%)

In the house 2.5 kW baseline is 60 kWh per day. In winter on average I use 2.3 times that with heating being the vast majority of the other 77 kWh/da. In summer the A/C seems to take only 27 kWh/da over the baseline. In the Summer the solar covers it all and then some and in the winter the issue is the heat. There isn't therfore, much incentive to try to beat down the baseline. It's the heating that I would want to address and as I have re-insulated, cleaned ducts and gone to an W/W heat pump there isn't much else I can do (except turn the thermostats down). As electricity is cheap (11¢/kWh) and as even in winter a fair chunk is covered by the sun there isn't much reason to worry about any of it except as an academic exercise.
 
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