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Man, people should really think about what their free time is worth - go volunteer at a charity or something. Jeez. Any schmuck with a job in an office building somewhere easily has access to "kilowatts" of power that could easily go unnoticed.
Teslas at least are limited by the output of their DC-DC converter (a few kW) unless they plan on doing this at a SuperCharger and hacking their battery apart.
Teslas at least are limited by the output of their DC-DC converter (a few kW) unless they plan on doing this at a SuperCharger and hacking their battery apart.
mknox
Well-Known Member
How exactly? Tesla meters the energy going into the battery pack and not used in other areas of the car's operation. If I leave my HVAC on in winter while Supercharging or L3 charging, the car will report receiving a few kWh less than the station reports delivering.
I mean, a few kWh is a totally different thing than the amount of power required to make substantial profit from bitcoin mining.
Chillaban has the answer. I'll add that I think Tesla can know when you use you hvac. A software guy designing an EV would make all information that can be captured available.
Tesla provides no cost electricity and has battery warranty liability. They are going to consider all the ways they can be abused by unauthorized use of their stuff.
mknox
Well-Known Member
Yeah, I just meant how would Tesla even know? Even if you charged, went away and drained the pack and came back to charge... how would Tesla even know what you're doing with that electricity?
Don't get me wrong... I don't endorse this or any of the other hair-brained schemes I've read about like powering your home from your car on "free" electricity.
BTW, what kind of demand (kW) are we talking about for this kind of bitcoin mining? I don't think the article said, but it must be substantial if folks are using it for supplemental home heating!
HankLloydRight
No Roads
When your Wh/mi is in the hundreds of thousands.
(I actually have a photo of that somewhere).
I know from my electric bill, I put more power into my Tesla batteries than I use for the entire household. In theory I could charge at a SC each afternoon, run my entire household at night off the Tesla, then recharge at the SC each morning to get to work. The Tesla is basically a mobile Powerwall.
If I could power 5 homes, I’d save about $1,000/month in electricity and have a free Tesla.
If I could power 5 homes, I’d save about $1,000/month in electricity and have a free Tesla.
mknox
Well-Known Member
When your Wh/mi is in the hundreds of thousands.
But it likely wouldn't be. Tesla seesm to only measure energy that comes out of the battery and drives the traction motors, nothing else. You can charge your car up and run it dead with the HVAC on high and the Wh/mi numbers won't change.
A while back I was ill and hospitalized while my car sat at home plugged in for an extended period. During that time, it had to top itself off daily to deal with the "vampire" losses. The car's display showed a "normal" Wh/mi number based on the 5 miles or so that got driven in each of the two months the car sat. When I calculated a Wh/mi number based on those same 5 or 10 miles against the energy I metered coming out of the wall, it was well over 10,000, but that was using a sub-meter on my charging circuit separate from the car.
HankLloydRight
No Roads
Nope. In my first year of ownership, I accidentally charged to 100% late at night, and had to go down to the garage and drain off the power. I turned on the heat, seats, lights, and fan to max, and let it run for two or three 30-minute intervals to bring down the SOC to 95% of so. The next day when I went to drive, I pulled out of the driveway - drove about 1/10 of a mile, and the Wh/mil was over 300,000. I posted that photo here on TMC when it happened, but I can't find it now.
LOL you know leaving it at full SOC for a few hours doesn't matter, right?
HankLloydRight
No Roads
A few hours, sure. But it was late at night and I couldn't leave the house until the next day, so it would have been at least 12 hours it not more. I was just being safe rather than sorry and degrade the battery even a little bit.
There has been some discussion about using car batteries as a grid storage solution. Maybe this makes sense at scale - I rarely need the full capacity of my 85kWh battery. Most of you folks that own Teslas are probably the same.
So most days I would be happy to sell my kWh back into the grid during peak times - except for the fact that I am parked at a GO lot in Scarboro and am not plugged in. But if I was plugged in and I got a text saying - the IESO is now paying $0.30/kWh - do you want to send energy into the grid - I would turn on a "decharge" function in my Tesla app. Or you could have this happen automatically if the price is above a certain rate and you have the option enabled. This is not unlike that program that they have now where you get a break for energy prices if you are willing to have your AC shut off when grid demand is very high. (Note that I would have charged overnight at offpeak rates at home - not at a Supercharger.)
Maybe car batteries can be a big part of the energy storage solution for intermittent electricity generation from renewable sources like wind and solar?
mknox
Well-Known Member
No, I think that is different. You are talking about an instantaneous consumption reading. I see that all the time in the winter regardless of whether I run HVAC. Not sure I've ever seen 6 digits, but 10,000+ Wh/mi is very common for me at 0.1 miles. The car is taking a high initial reading after first being "started" and is trying to extrapolate to 1 mile from 0.1 mile of data. Similarly, my past ICE cars would show triple digit instantaneous MPG if I was coasting down a hill, or single digit instantaneous MPG if accelerating up one, but the average would be "correct". The number here that matters is your average over 30 miles (or whatever you set it to), not the instantaneous number that appears before you've even gone a mile on the "Since Last Charge" or Since hh:mm" displays.
I have tons of data that shows when my car was parked for most of one month, and only driven about 5 miles, the car's monthly consumption display (I reset my Trip A monthly) was +/- 300 Wh/mi, but when I did my own math considering the amount of energy that went in to the car to make up for vampire drain, it was extremely high. The car only sees and records energy from the battery once it is "On".
mknox
Well-Known Member
You know, you're probably right in that Tesla can see a lot more than we can on the car's displays. I am using an after-market dongle that connects to the Tesla diagnostic connector to record stats about driving and charging. This device can "see" currents on both the input and output side of the on-board chargers, so it is likely Tesla has access to pretty much every point in the electrical systems.
HankLloydRight
No Roads
Nope again. It wasn't the "instantaneous" wh/mi reading. It was "Since last charge".. and it took quite a while (many miles) to slowly average back down to normal levels. It wasn't like I drove one mile and it snapped back to normal levels.
I stopped charging the evening before, drew down 5% of the battery, and then started driving the next day. The wh/mi definitely included all that energy going very little distance.
If it didn't include all of that 5% drawdown, then how did it get up over 300,000 wh/mi going any distance? I live on a flat road at sea level. I wasn't coasting down any big hills. Other than the 5% HVAC drawdown, everything else was entirely normal. Starting out from the garage after charging, I might see it go up to 600 or 700 wh/mi inside of the first mile. But never over 1,000, much less 300,000.
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mknox
Well-Known Member
Neither does mine. It takes at least 30 miles to get even near to "normal" values and even then, the 30 mile "snapshots" are higher in the cold of winter than my overall monthly number. That's the difference as you go from instantaneous values to values averaged over higher mileage intervals. Instantaneous values are interesting, but not really of much use to determine the car's actual overall energy use while underway any more than seeing 999 instantaneous MPG on my old ICE as I coasted down a hill was really very meaningful.
If I were to leave the car "on" while it was doing something to discharge the battery (i.e. leaving the car on and the door ajar with HVAC on) , then yes, it includes that energy in it's calculation. But if my car is "off" when something is discharging the battery, mine at least does not consider that energy use on the car's energy displays. I've been tracking every "drop" of electricity my car uses for the past 56 month based on a utility grade sub-meter on the charging circuit and comparing that against the car's own displays on a spreadsheet. Fascinating stuff.
I have read that Tesla may be over-cautious in having us worry about charging to 100%. I saw a story about a Tesloop in California that has been running a Model S for several years that is now very high mileage and has seen surprisingly little degradation:
This is What Happens When you put 300,000 miles on a Tesla
Tales from a Tesla Model S at 200k miles
This is What Happens When you put 300,000 miles on a Tesla
mknox
Well-Known Member
I know of someone personally who charges their 2013 S85 to 100% regularly and not only that, will often let it sit at that level. He has seen no unusual degradation either. For whatever reason, I do not have the courage to do that!
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