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i ended up doing a writeup of the work I did in case it's useful to others: Marc's Blog: electronics - Using a Tesla Model 3 as Emergency Power Source In Case of Grid Failure

I wrote a summary of my work here: Marc's Blog: electronics - Using a Tesla Model 3 as Emergency Power Source In Case of Grid Failure

So, I have an half unsolved question: what is the most battery efficient way to keep the DC-DC converter running? Camper mode with AC off, a low temperature, and fan on 1, seems to be the best I found so far. Ideally there should be a way to keep the DC-DC on while having the computer screen off...

So, I have an half unsolved question: what is the most battery efficient way to keep the DC-DC converter running? Camper mode with AC off, a low temperature, and fan on 1, seems to be the best I found so far. Ideally there should be a way to keep the DC-DC on while having the computer screen off...

I started this route for my project and I can confirm that on model3, the car only the charges the battery at a low rate. If you are using more than a few amps, the battery will actually discharge more quickly than the car can recharge it. This doesn't work in either direction: 1) the CLA as...

Two other related threads: Aftermarket Sub-woofer Amplifier Installation using DC-DC +12v Power Source MASTER THREAD: Powering house or other things with Model 3 12V battery

Thanks for posting me on yet another thread on the same topic. What I learned while doing my project is that the DC-DC system is a bit finicky in that it doesn't handle spikes like a battery would, and that may be a reason why Tesla doesn't want you to mess with it (although it was pretty well...

Sorry, what I wrote was indeed wrong in the details. They do allow you to store solar and use it at night, but it's stupid to do price-wise (i.e. you're losing money by not sending back solar to the grid), and by "you can't do TOU arbitration", I did mean that you can't charge your powerwall off...

To close off that discussion on this thread too, please go to How many amps can you get from the 12V system for emergency situations? for how I made it work. I now have a 2000W inverter that powers on and off at the same time than the car DC-DC system, without the big current inrush that was...

Here's what I did: I used this 2000W pure sine wave inverter: https://www.amazon.com/SUDOKEJI-Inverter-2000W-Display-Outlets/dp/B07RWHN22W/ref=sr_1_1 200A 12V relay: https://www.amazon.com/gp/product/B01MYPTVJD/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1 100W 1.8Ohm...

Did you disconnect the 12V from both sides? If you only disconnect the battery, the DC-DC will keep the car alive from the other side. If the DC-DC trips, or you disconnect it from under the rear seat, and then you also disconnect the battery, the car's computers have no power and absolutely...

Interesting, I didn't think about those, but I am dealing with 200A, I'm not sure a few of those, even in parallel, are going to do the trick. (3000W inverter at 12V is actually 250A) Other people who worked on this talked about a bypass relay once the inrush is over, and honestly you need a...

Thanks. It's a long document, what part was what actually helped? I'd think that if you disconnect 12V from both sides (battery and DC-DC side), the car should fully lose power and forget the old battery. Are you sure that it's not enough?

How is your battery? Did you keep driving around for months with the "replace battery" prompt? If you didn't replace it, try this: 1) unplug it from the car entirely 2) recharge it with a regular charger 3) plug it back in The car will hopefully detect it as a new battery and should not give you...

You are talking about a Model S, not a Model 3, correct? As stated earlier, I tried an 85W load with a cheap small inverter, and is was just around 7A. Even with that, the battery was discharging faster than it was recharging, even when I removed the buffer battery that you say is the cause of...

Kind of, read on :) Ok, so I hear and understand everything you're saying but it seems that model3 is clearly limiting the charge going to the buffer 12V battery. From what you're saying, I should just be able to drain 10A from it with a small inverter, and it should get topped off quickly...

Out of curiosity, how does the car decide the battery needs replacing? Is it possible it see this from a low voltage once even though the battery is good? If so, can that condition be reset to let the car verify if the 12V battery is truly going bad, or whether it was a temporary condition...

I'm not going to fork this thread on powerwalls since I specifically said I was not interested in them, and knew why I was not, but in a nutshell, at least in California, PG&E does not allow you to do time of use shifting during a powerwall and storing solar into a powerwall to use it at night...

Agreed. Honestly I don't need 3000W, I just oversized the inverter to make sure it doesn't die and can handle power on spikes as discussed earlier in the thread. In the meantime, I found where to get a proper 12V connection including the warning about using a pre-charging resistor to handle the...

There are pros and cons, I've given some, there are more. I have looked into that option and I'm not interested. I have 70Kwh or so in my car when it's full, I'm interested in using that instead if need be.

Do you have a model S or model 3? If model 3, where are those 50A posts in the frunk?

I just replied to this :) Spoiler alert, when PG&E kills power to your entire neighborhood, don't expect your local gas station to be working either, and then you're back on your crappy 2 year old 5 gallon gas container of which a 4th manage to evaporate and leaving you for stale gas that is...

The 3000W inverter I have is technically supposed to do 250A at peak use. It came with thick (and short-ish) cables. I agree that getting 100A or more on any distance requires thick cables. To be honest, I'll cross that bridge when I get to it (thicker cables), for now I'd be happy with even...

Thank you for that info. Ok, then it's only the power steering that may be using 12V at 100A peak from what I've been told. Still, there should be a 12V bus that has more than 8A, I will look at the sound threads, thanks, and then worry about keeping the car awake so that it doesn't shut down...

250W is what my fridge uses when it's on, and it's running maybe 33% of the time, so I do think estimating my averaged emergency power need to 250W (let's say even 500W) is not unreasonable at all. I just bought a 3000W inverter because all those inverters don't work well when you get close to...

You are correct, 200A is a power bar, not a wire anymore :) To be clear, I am not looking at getting 200A from the car, but my inverter is indeed designed to draw over 200A, that's the only way you can get 3000W from 12V. you need thick wires, and they're around the thickness of what good...

Question: Is there a better 12V bus I should tap into that gets more amps from the DC-DC converter than what is being sent to the battery (only a few amps it seems) Details: I'm interested in getting a decent amount of amps from my car while it's parked at home if I'm in a power emergency...

Sorry that it didn't work for you. I was amazed that it worked for me once with AP2.5, at night no less: (jump to 1:15)

I think you arrived with just over 20% left? That sounds about right given the warmer weather and that you drove more slowly than me (and didn't hit snow) I've left KW with 60% and still made it. The drive home is pretty easy with all the regen. As you said, if you charge too much, you actually...

Yes, there is no question that this will not work every day in every condition. I make this very clear in my post. I did show how snow and cold affected my expected range quite a bit. I arrived with 9% instead of a computed 20% when I left I also talk about defrosting, so I think you may not...

Some of you may remember that I tried this in my model S 90D some years back, and it wasn't possible without a supercharger stop in Manteca. Marc's Blog: cars - Driving from the South Bay Area to Kirkwood in a Tesla Model S 90D With the model 3 AWD LR (and obviously the RWD even more as long as...

thanks for the report. I did the same in a 90D, once in heavy snow Marc's Blog: cars - Driving from the South Bay Area to Kirkwood in a Tesla Model S 90D

You are correct. I looked for an AP forum before posting here, and did not find one.

I'd have expected APv2 to be so much better than v1 by now that I'd have gone to buy a new model S, but honestly I never expected APv1 to get much better. In case you don't know the details of the APv1 hardware, it's really quite limited. That's why I'm actually pretty happy with APv1...

I didn't hit it, but waited as long as I could before taking over, so yeah, it was close.

Right, so you basically had the same issue than me with , except hopefully your cones were smaller than the big ones I would have hit. Or did the local road people actually just put cones in the middle of the lane without warning and without slowly closing the lane from the side, first?

Err, that's not a legend at all. It's happened to me 2-3 times. I was reporting a previous bug I had found (saved in my phone so that I don't forget) and testing how it would react to a car stopped at a red light. Car never saw it, I waited as long as I felt I could before I slammed on the...

Hi TaoJones: I wrote wrong as you noticed. I meant to say "blind to stop signs". Now, it's possible that maybe it's not blind to them but of course doesn't react to them at this time (which is as advertised). I didn't know it could tell red lights but that the code was not enabled (which again...

I'm well aware that the hardware on APv2 is substantially better, but I've failed to find any information of whether APv2 currently has an AP that behaves functionally better than APv1. I have v1 and I've been waiting for v2 to be sufficiently better for me to consider upgrading (i.e. changing...

How do you know they are very close? Did you drive 2 of them from full to close to empty side by side? Or are there numbers from different people taken in different conditions? Did anyone drive a 90D from full to near empty and record the kwh used by the trip meter?

That's correct. That's what I was saying with internal resistance. You don't get full capacity from any battery if you're drawing a fair amount of current from them. So the way Tesla uses the cells, they are easily 4Kwh fewer than their marketing rating (and apparently, they may not quite have...

Let's calm down :) 1) you don't have to figure it out. I was curious to know but let's be honest, you don't need to do this to drive your car 2) we already know that your 85Kwh pack is only about 81Kwh an my 90Kwh pack is also less than 90Kwh since tesla sadly does overstate the usable battery...

Someone needs to do the test :) I seldom do long drives and the one I did twice required that I charge in the middle (going up a mountain at the end), so it probably won't be me :) Please post here if you find someone who has done a close enough test.

I agree with you, and have no data that shows that a 90D car driving from 100% to 0% isn't getting 81 or 82Kwh. Note, I'm not saying that the uncertainty in the percentage display on the dashboard proves that my battery has more driving capacity than an 85 car, I'm just saying that it's a valid...

Two 90D cars can effectively give you a different battery charge percentage on the dashboard while having the actual same battery charge. It's because the percentage is software calculated from a bunch of approximations and can grow to be wrong over time (within bounds). But the main point...

Ok, the thread is a bit old, but I got some information from a Tesla Engineer after reporting the possible problem to my service advisor. As a reminder, out of 4 longish trips, I got a calculated 75-76Kwh of fully usable battery by calculating energy used while driving (no stops) vs percent of...

No, I'm only using the trip meter to show Kwh used since last start. I do not use range for anything or any calculation.

Sorry, most of your arguments do not apply. You are talking about range in miles, I'm talking about Kwh use. Most of what you mentioned impacts range, but does not impact the Kwh used number and percentage of battery left, being farther away from reality

Ok, then can Tesla read what charge the BMS thinks I have (in Kwh) if I charge the car to 100%? That would lay the issue to rest, but my service manager said it wasn't possible when I asked him (hence my confusion)

So the CAN logger will give you Kwh left as opposed to percent left? If it were that easy, people would know that their 85D really only has (apparently) 80Kwh of capacity. Can you describe in more details exactly what you get from the CAN logger and how it is not extrapolating itself? as well...